Dissertations / Theses: 'Biodegradable nanocomposites'

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Aydin, Erkin. "Biodegradable Polymer - Hydroxyapatite Nanocomposites For Bone Plate Applications." Phd thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612252/index.pdf.

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Long bone fractures are fixed with bone plates to restrain movement of bone fragments. Fracture site must experience some pressure for proper healing. Bone plates are mostly made up of metals having 5 - 10 times higher elastic modulus than bones and most of the load is carried by them, leading to stress shielding and a bony tissue with low mineral density and strength. To avoid these problems, biodegradable polymer-based composite plates were designed and tested in this study. Poly(L-lactide) and Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) biodegradable polymer composite fibers containing hydroxyapatite (HAP) nanoparticles were produced by extrusion and spinning techniques to reinforce the polymeric bone plates. The composite fibers were expected to mimic the natural organization of bone so that HAP nanorods aligned parallel to the loading axis of bone plate. Also, lactic acid was grafted on HAP surfaces and had a positive effect on the mechanical properties of the PLLA composites. A 50% (w/w) HAP nanoparticle content was found to increase tensile modulus value (4.12 GPa) ca. 2.35 times compared to the pure polymeric fiber with a reduction to one third of the original UTS (to 50.4 MPa). The fibers prepared were introduced to polymeric plates with their long axes parallel. Fiber reinforced bone plates were compression tested longitudinally and up to a 4% increase in the Young&rsquo
s Modulus was observed. Although this increase was not high was not high probably due to the low fiber content in the final plates, this approach was found to be promising for the production of biodegradable polymeric bone plates with mechanical values closer to that of cortical bones. Biological compatibility of fibers was validated with in vitro testing. The osteoblasts attached and spread on the fibers indicating that bone fractures fixed with these could attract of bone forming osteoblasts into defect area and help speed up healing.

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Li, Yonghui. "Biodegradable poly(lactic acid) nanocomposites: synthesis and characterization." Diss., Kansas State University, 2011. http://hdl.handle.net/2097/8543.

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Doctor of Philosophy
Department of Grain Science and Industry
X. Susan Sun
Biobased polymers derived from renewable resources are increasingly important due to acute concerns about the environmental issues and limited petroleum resources. Poly(lactic acid) (PLA) is such a polymer that has shown great potential to produce biodegradable plastics. However, low glass transition temperature (Tg), low thermal stability, slow biodegradation rate, and high cost limit its broad applications. This dissertation seeks to overcome these limitations by reinforcing PLA with inorganic nanoparticles and low-cost agricultural residues. We first synthesized PLA nanocomposites by in situ melt polycondensation of L-lactic acid and surface-hydroxylized nanoparticles (MgO nanocrystals and TiO2 nanowires) and investigated the structure-property relationships. PLA grafted nanoparticles (PLA-g-MgO, PLA-g-TiO2) were isolated from the bulk nanocomposites via repeated dispersion/centrifugation processes. The covalent grafting of PLA chains onto nanoparticle surface was confirmed by Fourier transform infrared spectroscopy and thermalgravimetric analysis (TGA). Transmission electron microscopy and differential scanning calorimetry (DSC) results also sustained the presence of the third phase. Morphological images showed uniform dispersion of nanoparticles in the PLA matrix and demonstrated a strong interfacial interaction between them. Calculation based on TGA revealed that more than 42.5% PLA was successfully grafted into PLA-g-MgO and more than 30% was grafted into PLA-g-TiO2. Those grafted PLA chains exhibited significantly increased thermal stability. The Tg of PLA-g-TiO2 was improved by 7 °C compared with that of pure PLA. We also reinforced PLA with low-value agricultural residues, including wood flour (WF), soy flour (SF), and distillers dried grains with solubles (DDGS) by thermal blending. Tensile measurements and morphological images indicated that methylene diphenyl diisocyanate (MDI) was an effective coupling agent for PLA/WF and PLA/DDGS systems. MDI compatibilized PLA/WF and PLA/DDGS composites showed comparable tensile strength and elongation at break as pure PLA, with obviously increased Young’s modulus. Increased crystallinity was observed for PLA composites with SF and DDGS. Such PLA composites have similar or superior properties compared with pure PLA, especially at a lower cost and higher biodegradation rate than pure PLA. The results from this study are promising. These novel PLA thermoplastic composites with enhanced properties have potential for many applications, such as packaging materials, textiles, appliance components, autoparts, and medical implants.

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Saxena, Amit. "Nanocomposites based on nanocellulose whiskers." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/47524.

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Environmental concerns arising from the use of non-degradable plastics have resulted in search for suitable substitutes. The thesis deals with new nanostructured composites based on reinforcement of nanocellulose whiskers in "green" polymers such as xylan. Since the reinforcement filler and the matrix are both biobased and are thereby environmental friendly. Xylan incorporated with cellulose whiskers films provided with improved water and oxygen barrier properties. It appears that the high degree of crystallinity of cellulose whiskers, dense composite structure formed by the whiskers and rigidly hydrogen-bonded cellulose whiskers can cause cellulose whiskers to form integrated matrix which contribute to substantial benefit in the overall reduction of transmission rate. The spectral data obtained for the NCW/xylan nanocomposite films showed that the amount of xylan adsorbed to cellulose increases with the addition of NCW in the matrix. In addition, NMR T2 relaxation experiments studies were conducted to investigate the change in the nature of carbohydrate-water interactions as a result of NCW incorporation. These results facilitated an improved understanding of the mechanisms involved in the superior barrier and mechanical properties of xylan-whisker nanocomposite films. XRD studies show that when a xylan-whisker nanocomposite films is formed the mixing occurs on the atomic scale and NCW loading increases the matrix crystallinity.

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Bhatia, Amita, and abhatia78@yahoo com. "Experimental Study of Structure and Barrier Properties of Biodegradable Nanocomposites." RMIT University. Civil, Environmental and Chemical Engineering, 2008. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20090304.143545.

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As nanocomposites provide considerable improvements in material properties, scientists and engineers are focussing on biodegradable nanocomposites having superior material properties as well as degradability. This thesis has investigated the properties of biodegradable nanocomposites of the aliphatic thermoplastic polyester, poly (lactide acid) (PLA) and the synthetic biodegradable polyester, poly (butylene succinate) (PBS). To enhance the properties of this blend, nanometer-sized clay particles, have been added to produce tertiary nanocomposite. High aspect ratio and surface area of clay provide significant improvement in structural, mechanical, thermal and barrier properties in comparison to the base polymer. In this study, a series of PLA/PBS/layered silicate nanocomposites were produced by using a simple twin-screw extruder. PLA/PBS/Cloisite 30BX nanocomposites were prepared containing 1, 3, 5, 7 and 10 wt% of C30BX clay, while PLA and PBS polymers compositions were fixed at a ratio of 80 to 20. This study also included the validation of a gas barrier model for these biodegradable nanocomposites. WAXD indicated an exfoliated structure for nanocomposites having 1 and 3 wt% of clay, while predominantly development of intercalated structures was noticed for nanocomposites higher than 5 wt% of clay. However, TEM images confirmed a mixed morphology of intercalated and exfoliated structure for nanocomposite having 1 wt% of clay, while some clusters or agglomerated tactoids were detected for nanocomposites having more than 3 wt% of clay contents. The percolation threshold region for these nanocomposites lied between 3-5 wt% of clay loadings. Liquid-like behaviour of PLA/PBS blends gradually changed to solid-like behaviour with the increase in concentration of clay. Shear viscosity for the nanocomposites decreased as shear rate increased, exhibiting shear thinning non-Newtonian behaviour. Tensile strength and Young's modulus initially increased for nanocomposites of up to 3 wt% of clay but then decreased with the introduction of more clay. At high clay content (more than 3 wt%), clay particles tend to aggregate which causes microcracks at the interface of clay-polymer by lowering the polymer-clay interaction. Percentage elongation at break did not show any improvement with the addition of clay. PLA/PBS blends were considered as immiscible with each other as two separate glass transition and melting temperatures were observed in modulated differential scanning calorimetry (MDSC) thermograms. MDSC showed that crystallinity of the nanocomposites was not much affected by the addition of clay and hence some compatibilizer is required. Thermogravimetric analysis showed that the nanocomposite containing 3 wt% of clay demonstrated highest thermal stability compared to other nanocomposites. Decrease in thermal stability was noticed above 3 wt% clay; however the initial degradation temperature of nanocomposites with 5, 7 and 10 wt% of clay was higher than that of PLA/PBS blend alone. Gas barrier property measurements were undertaken to investigate the transmission of oxygen gas and water vapours. Oxygen barrier properties showed significant improvement with these nanocomposites, while that for water vapour modest improvement was observed. By comparing the relative permeabilities obtained from the experiments and the model, it was concluded that PLA/PBS/clay nanocomposites validated the Bharadwaj model for up to 3 wt% of clay concentration.

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Krikorian, Vahik. "Bio-nanocomposites fabrication and characterization of layered silicate nanocomposites based on biocompatible/biodegradable polymers / by Vahik Krikorian." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file , 11.06 Mb, 148 p, 2005. http://wwwlib.umi.com/dissertations/fullcit/3187609.

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Tang, Xiaozhi. "Use of extrusion for synthesis of starch-clay nanocomposites for biodegradable packaging films." Diss., Manhattan, Kan. : Kansas State University, 2008. http://hdl.handle.net/2097/546.

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Morales, Gámez Laura Teresa. "Study of nanocomposites prepared from polyamides and biodegradable polyesters and poly(ester amide)s." Doctoral thesis, Universitat Politècnica de Catalunya, 2012. http://hdl.handle.net/10803/55251.

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Polymer clay nanocomposites of polyamides and biodegradable polymers with three kinds of organomodified clays were prepared by different techniques (in situ polymerization, solution casting, and melt mixing). The polymers used in this research were nylons 56, 65 and 47 and the biodegradable polymers: poly (glycolic acid-alt-6-hydrohexanoic acid) and poly(glycolic acid-alt-6-aminohexanoic acid). The development of biodegradable nanocomposites with improved or modified material properties is an interesting topic since these new materials are expected to replace already existing biodegradable and non-biodegradable commodity plastics in some specific applications.This project aims to study the influence of clay particles incorporated in a polymer matrix on the crystallization processes, the study of the in situ polymerization kinetics of mixtures of clays and monomers of biodegradable polymers, as well as the influence of nanoparticles on the thermal behavior and morphologic parameters. Even-odd, and odd-even polyamides were chosen to study the Brill transition and to prepare nanocomposites with organomodified clays. These polyamides have a peculiar structure where hydrogen bonds are established along two different directions. X-ray diffraction as well as SAXS-WAXD synchrotron experiments were employed to study the structural changes induced by temperature, during heating and cooling. Different organomodified clays were used to prepare nanocomposites, which final structure was found to be dependent on the preparation method. Nanocomposites derived from biodegradable polymers were characterized by means of X-ray diffraction and transmission electron microscopy. Morphological studies showed that the extent of clay dispersion depended on the clay type and on the preparation technique. Hence, exfoliated and intercalated nanocomposites could be obtained. The final nanocomposite structure was found to have a great influence on both cold and hot crystallization processes. Hence, the crystallization rate increased and decreased with respect to the neat polymer when intercalated and exfoliated structures were respectively obtained. The kinetics of the polymerization process was also studied by means of FTIR and SAXS-WAXD. The results indicate that the presence of the organomodified clay had a remarkable effect on the kinetic parameters.

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Asem, Heba. "Synthesis of Polymeric Nanocomposites for Drug Delivery and Bioimaging." Licentiate thesis, KTH, Funktionella material, FNM, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-186300.

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Nanomaterials have gained great attention for biomedical applications due to their extraordinary physico-chemical and biological properties. The current dissertation presents the design and development of multifunctional nanoparticles for molecular imaging and controlled drug delivery applications which include biodegradable polymeric nanoparticles, superparamagnetic iron oxide nanoparticles (SPION)/polymeric nanocomposite for magnetic resonance imaging (MRI) and drug delivery, manganese-doped zinc sulfide (Mn:ZnS) quantum dots (QDs)/ SPION/ polymeric nanocomposites for fluorescence imaging, MRI and drug delivery.Bioimaging is an important function of multifunctional nanoparticles in this thesis. Imaging probes were made of SPION and Mn:ZnS QDs for in vitro and in vivo imaging. The SPION have been prepared through a high temperature decomposition method to be used as MRI contrast agent. SPION and Mn:ZnS were encapsulated into poly (lactic-co-glycolic) acid (PLGA) nanoparticles during the particles formation. The hydrophobic model drug, busulphan, was loaded in the PLGA vesicles in the composite particles. T2*-weighted MRI of SPION-Mn:ZnS-PLGA phantoms exhibited enhanced negative contrast with r2* relaxivity of 523 mM-1 s-1. SPION-Mn:ZnS-PLGA-NPs have been successfully applied to enhance the contrast of liver in rat model.The biodegradable and biocompatible poly (ethylene glycol)-co-poly (caprolactone) (PEG-PCL) was used as matrix materials for polymeric nanoparticles -based drug delivery system. The PEG-PCL nanoparticles have been constructed to encapsulate SPION and therapeutic agent. The encapsulation efficiency of busulphan was found to be ~ 83 %. PEG-PCL nanoparticles showed a sustained release of the loaded busulphan over a period of 10 h. The SPION-PEG-PCL phantoms showed contrast enhancement in T2*-weighted MRI. Fluorescein-labeled PEG-PCL nanoparticles have been observed in the cytoplasm of the murine macrophage cells (J774A) by fluorescence microscopy. Around 100 % cell viability were noticed for PEG-PCL nanoparticles when incubated with HL60 cell line. The in vivo biodistribution of fluorescent tagged PEG-PCL nanoparticles demonstrated accumulation of PEG-PCL nanoparticles in different tissues including lungs, spleen, liver and kidneys after intravenous administration.

QC 20160516

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Kaur, Jasmeet. "Properties of biologically relevant nanocomposites: effects of calcium phosphate nanoparticle attributes and biodegradable polymer morphology." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/33981.

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This research is directed toward understanding the effect of nanoparticle attributes and polymer morphology on the properties of the nanocomposites with analogous nanoparticle chemistry. In order to develop this understanding, polymer nanocomposites containing calcium phosphate nanoparticles of different specific surface areas and shapes were fabricated and characterized through thermal and thermomechanical techniques. Nanoparticles were synthesized using reverse microemulsion technique. For nanocomposites with different surface area particles, the mobility of amorphous polymer chains was restricted significantly by the presence of particles with an interphase network morphology at higher loadings. Composites fabricated with different crystallinity matrices showed that the dispersion characteristics and reinforcement behavior of nanoparticles were governed by the amount of amorphous polymer fraction available. The study conducted on the effect of nanoparticle shape with near-spherical and nanofiber nanoparticles illustrated that the crystallization kinetics and the final microstructure of the composites was a function of shape of the nanoparticles. The results of this research indicate that nanoparticle geometry and matrix morphology are important parameters to be considered in designing and characterizing the structure-property relationship in polymer nanocomposites.

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Svagan, Anna. "Bio-inspired cellulose nanocomposites and foams based on starch matrix." Doctoral thesis, KTH, Biokompositer, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-9666.

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In 2007 the production of expanded polystyrene (EPS) in the world was over 4 million tonnes and is expected to grow at 6 percent per year. With the increased concern about environmental protection, alternative biodegradable materials from renewable resources are of interest. The present doctoral thesis work successfully demonstrates that starch-based foams with mechanical properties similar to EPS can be obtained by reinforcing the cell-walls in the foams with cellulose nanofibers (MFC). High cellulose nanofiber content nanocomposites with a highly plasticized (50/50) glycerol-amylopectin starch matrix are successfully prepared by solvent-casting due to the high compatibility between starch and MFC. At 70 wt% MFC, the nanocomposites show a remarkable combination of high tensile strength, modulus and strain to failure, and consequently very high work to fracture. The interesting combination of properties are due to good dispersion of nanofibers, the MFC network, nanofiber and matrix properties and favorable nanofiber-matrix interaction. The moisture sorption kinetics (30% RH) in glycerol plasticized and pure amylopectin film reinforced with cellulose nanofibers must be modeled using a moisture concentration-dependent diffusivity in most cases. The presence of cellulose nanofibers has a strong reducing effect on the moisture diffusivity. The decrease in zero-concentration diffusivity with increasing nanofiber content could be due to geometrical impedance, strong starch-MFC molecular interaction and constrained swelling due to the cellulose nanofiber network present. Novel biomimetic starch-based nanocomposite foams with MFC contents up to 40 wt% are successfully prepared by freeze-drying. The hierarchically structured nanocomposite foams show significant increase in mechanical properties in compression compared to neat starch foam. Still, better control of the cell structure could further improve the mechanical properties. The effect of cell wall composition, freeze-drying temperature and freezing temperature on the resulting cell structure are therefore investigated. The freeze-drying temperature is critical in order to avoid cell structure collapse. By changing the starch content, the cell size, anisotropy ratio and ratio between open and closed cells can be altered. A decrease in freezing temperature decreases the cell size and increases the anisotropy ratio. Finally, mechanical properties obtained in compression for a 30 wt% MFC foam prepared by freeze-drying demonstrates comparable properties (Young's modulus and yield strength) to expanded polystyrene at 50% RH and similar relative density. This is due to the reinforcing cellulose nanofiber network within the cell walls.
QC 20100913

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11

Vidhate, Shailesh. "Biodegradable Poly(hydroxy Butyrate-co-valerate) Nanocomposites And Blends With Poly(butylene Adipate-co-terephthalate) For Sensor Applications." Thesis, University of North Texas, 2011. https://digital.library.unt.edu/ark:/67531/metadc103405/.

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The utilization of biodegradable polymers is critical for developing “cradle to cradle” mindset with ecological, social and economic consequences. Poly(hydroxy butyrate-co-valerate) (PHBV) shows significant potential for many applications with a polypropylene equivalent mechanical performance. However, it has limitations including high crystallinity, brittleness, small processing window, etc. which need to be overcome before converting them into useful products. Further the development of biodegradable strain sensing polymer sensors for structural health monitoring has been a growing need. In this dissertation I utilize carbon nanotubes as a self sensing dispersed nanofiller. The impact of its addition on PHBV and a blend of PHBV with poly(butylene adipate-co-terephthalate) (PBAT) polymer was examined. Nanocomposites and blends of PHBV, PBAT, and MWCNTs were prepared by melt-blending. The effect of MWCNTs on PHBV crystallinity, crystalline phase, quasi-static and dynamic mechanical property was studied concurrently with piezoresistive response. In PHBV/PBAT blends a rare phenomenon of melting point elevation by the addition of low melting point PBAT was observed. The blends of these two semicrystalline aliphatic and aromatic polyesters were investigated by using differential scanning calorimetry, small angle X-ray scattering, dynamic mechanical analysis, surface energy measurement by contact angle method, polarized optical and scanning electron microscopy, and rheology. The study revealed a transition of immiscible blend compositions to miscible blend compositions across the 0-100 composition range. PHBV10, 20, and 30 were determined to be miscible blends based on a single Tg and rheological properties. The inter-relation between stress, strain, morphological structure and piezoresistive response of MWCNT filled PHBV and PHBV/PBAT blend system was thoroughly investigated. The outcomes of piezoreistivity study indicated MWCNT filled PHBV and PHBV/PBAT blend system as a viable technology for structural health monitoring. Finally, the compostability of pure polymer, blend system, and MWCNT filled system was studied indicating that PBAT and CNT decreased the biodegradability of PHBV with CNT being a better contributor than PBAT.

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Hassan, Mohamed K. I. "Novel Elastomers, Characterization Techniques, and Improvements in the Mechanical Properties of Some Thermoplastic Biodegradable Polymers and Their Nanocomposites." University of Cincinnati / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1086633832.

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Sonseca, Olalla Agueda. "DEVELOPMENT OF SHAPE-MEMORY COMPOSITES BASED ON A BIODEGRADABLE POLYESTER ELASTOMER." Doctoral thesis, Universitat Politècnica de València, 2019. http://hdl.handle.net/10251/54129.

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[EN] The current PhD thesis deals with the development and characterization of novel nanocomposites based on biodegradable poly(mannitol sebacate) (PMS) matrices with tailored properties and shape-memory capabilities for biomedical applications. Two types of fillers -cellulose nanocrystals (CNC) and electrospun poly(lactic acid) nanofibers (NF-PLA)- were used as reinforcement in order to induce and/or enhance the shape-memory properties of PMS matrices. Also, different crosslinking profiles and stoichiometric ratios between mannitol and sebacic acid (1:1 and 1:2) were studied and evaluated to obtain samples with low and high degrees of crosslinking. An appropriate combination of the crosslinking profile and the monomer ratio for PMS matrix, as well as the addition of low content of CNC, allowed the development of PMS/CNC nanocomposites with a wide range of mechanical properties and degradation profiles. On the other hand, highly oriented poly(lactic acid) (PLA) nanofiber mats obtained by electrospinning were embedded in the PMS matrices. An enhancement of up to 53-fold in the Young's modulus was observed for PMS/NF-PLA nanocomposites filled with 15 wt% of PLA nanofibers. The incorporation of fillers (CNC and NF-PLA) allowed the development of thermally active shape-memory nanocomposites with an enhancement of parameters such as recovery stress and shape fixity. The electrospun PLA-reinforced nanocomposites, offered the best balance of mechanical and thermal properties, as well as a greater control of the transition temperature for switching the change of shape, within a useful range of temperatures. Owing to that, these materials may be of interest as smart responsive systems in long-term biomedical applications.
[ES] La presente tesis doctoral, se centra en el desarrollo y caracterización de nuevos nanocompuestos biodegradables, a partir de matrices de poli(mannitol sebacato) (PMS) con propiedades a medida y capacidades de memoria de forma para aplicaciones biomédicas. Dos tipos de cargas -nanocristales de celulosa (CNC) y nanofibras de ácido poliláctico (NF-PLA) obtenidas mediante electrospinning- se han utilizado como refuerzo, con la finalidad de inducir y/o mejorar las propiedades de memoria de forma en matrices de PMS. Se han estudiado y evaluado diferentes tratamientos de curado y ratios de reacción entre el mannitol y ácido sebácico (1:1 y 1:2), con la finalidad de obtener muestras con bajo y alto grado de reticulación. Una combinación adecuada del tratamiento de curado y el ratio entre monómeros del PMS, así como la adición de bajos contenidos de CNC, permitió desarrollar nanocompuestos de PMS/CNC con un amplio rango de propiedades mecánicas y perfiles de degradación. Por otro lado, se han producido mats de nanofibras de ácido poliláctico (PLA) con alta orientación mediante la técnica de electrospinning, para embeberse en matrices de PMS, observándose una mejora de hasta 53 veces en el módulo de Young para nanocompuestos de PMS/NF-PLA con un 15% en peso de nanofibras. La incorporación de cargas (CNC y NF-PLA) permitió el desarrollo de nanocompuestos con memoria de forma activada térmicamente, con una mejora de parámetros tales como la fuerza de recuperación y la capacidad de fijación. Los nanocompuestos reforzados con NF-PLA obtenidas por electrospinning, ofrecieron el mejor balance de propiedades mecánicas y térmicas, así como un mayor control de la temperatura de transición para la activación del cambio de forma en un intervalo útil de temperaturas. Por todo ello, estos materiales pueden resultar de interés como sistemas activos en aplicaciones biomédicas de larga duración.
[CAT] La present tesi doctoral se centra en el desenvolupament i caracterització de nous nanocompostos biodegradables a partir de matrius de poli(mannitol sebacato) (PMS) amb propietats a mesura i capacitats de memòria de forma per a aplicacions biomèdiques. Dos tipus de càrregues -nanocristals de cel·lulosa (CNC) i nanofibres d'àcid polilàctic (NF-PLA) obtingudes mitjançant electrospinning- s'han utilitzat com a reforç amb la finalitat d'induir i/o millorar les propietats de memòria de forma en matrius de PMS. S'han estudiat i avaluat diferents tractaments de curat i ràtios de reacció entre el mannitol i àcid sebàcic (1:1 i 1:2) amb la finalitat d'obtenir mostres amb baix i alt grau de reticulació. Una combinació adequada del tractament de curat i el ràtio entre monòmers del PMS, així com l'addició de baixos continguts de CNC, va permetre desenvolupar nanocompostos de PMS/CNC amb un ampli rang de propietats mecàniques i perfils de degradació. D'altra banda, s'han produït mats de nanofibres d'àcid polilàctic (PLA) amb alta orientació mitjançant la tècnica de electrospinning, per embeure's en matrius de PMS, observant-se una millora de fins a 53 vegades en el mòdul de Young per nanocompostos de PMS/NF-PLA amb un 15% en pes de nanofibres. La incorporació de càrregues (CNC i NF-PLA) va permetre el desenvolupament de nanocompostos amb memòria de forma activada tèrmicament, amb una millora de paràmetres tals com la força de recuperació i la capacitat de fixació. Els nanocompostos reforçats amb NF-PLA obtingudes per electrospinning, van oferir el millor balanç de propietats mecàniques i tèrmiques, així com un major control de la temperatura de transició per a l'activació del canvi de forma en un interval útil de temperatures. Per tot això, aquests materials poden resultar d'interés com a sistemes actius en aplicacions biomèdiques de llarga durada.
Sonseca Olalla, A. (2015). DEVELOPMENT OF SHAPE-MEMORY COMPOSITES BASED ON A BIODEGRADABLE POLYESTER ELASTOMER [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/54129
TESIS

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Javadian, Hamedreza. "Study on adsorption behavior of rare earth elements onto magnetic nanocomposites of carboxymethyl chitosan, alginate and novel biodegradable polyamide." Doctoral thesis, Universitat Politècnica de Catalunya, 2020. http://hdl.handle.net/10803/671253.

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Rare Earth Elements (REEs) are known as the remarkable components in many technologies that are driving the modern world. They are widely used in chemical engineering, permanent magnets, fluorescent lighting, sensors, cell phones, lasers, electronics, rechargeable batteries, etc., because of their unique physicochemical properties. In order to supply the required amounts of these elements and fulfil their increasing demands, it is necessary to recovery this elements from secondary sources. Despite many efforts that have been done on recycling REEs, only less than 1% of REEs is recycled which can be due to the numerous challenges, such as collection of different final products and separation of REEs from other contaminants/metals. Among the different techniques used for separation and purification of REEs from aqueous solution, biosorption has received great attention in recent decades. In this sense, biopolymers have been vastly utilized for the treatment of solutions containing metals. Alginate and chitosan are two kinds of biopolymers that have been utilized by many researchers due to being environmentally-friendly and effective. The purpose of this work was to study the adsorption of Nd+3, Tb+3, and Dy+3 ions from aqueous solutions by using new magnetic nanocomposites based on calcium alginate (CA) and carboxymethyl chitosan (CMC) biopolymers, a novel synthetic biodegradable polyamide named poly(pyrimidine-thiophene-amide) (P(PTA)), and magnetic nanoparticles (Ni0.2Zn0.2Fe2.6O4). The synthesis of the P(PTA) was performed in two steps. Firstly, a diamine-phenol monomer (TMAPD) was synthesized. Secondly, the polymer was obtained by polycondensation of TMAPD in 1,3-dipropyl imidazolium bromide ionic liquid as a solvent to avoid the use of the toxic triphenyl phosphite/N-methylpyrolidone/pyridine/LiCl that is required in the conventional direct polycondensation. The magnetic nanoparticles (Ni0.2Zn0.2Fe2.6O4) were synthesized by hydrothermal technique. The magnetic nanocomposites named CA/CMC/Ni0.2Zn0.2Fe2.6O4, CA/P(PTA)/Ni0.2Zn0.2Fe2.6O4, CMC/P(PTA)/Ni0.2Zn0.2Fe2.6O4 were synthesized by gelation method, and P(PTA)/Ni0.2Zn0.2Fe2.6O4 was synthesized by hydrothermal method. Different techniques were used to analyze the synthesized materials. XRD was used to confirm the formation of the Ni0.2Zn0.2Fe2.6O4 and determine the size of the particles. The P(PTA) synthesis was confirmed by NMR analysis. The morphologies of the Ni0.2Zn0.2Fe2.6O4 and magnetic nanocomposites was investigated by FE-SEM technique. TGA was used for determining the thermal stability of the P(PTA) and magnetic nanocomposites. EDX was used for elemental analysis of the Ni0.2Zn0.2Fe2.6O4, P(PTA), and magnetic nanocomposites. VSM analysis was applied to determine the magnetic properties of the Ni0.2Zn0.2Fe2.6O4 and the magnetic nanocomposites. To determine the functional groups of all products, FT-IR analysis was applied. Finally, the adsorption of the REEs was investigated in single and ternary batches, and column experiments. For the batch experiments, the effects of main parameters such as pH, contact time, adsorbent dosage, initial concentration, ionic strength, and temperature on the adsorption of the REEs were investigated in details. In addition, DeltaG', DeltaH', DeltaS' as thermodynamic parameters were determined. In ternary system, response surface methodology based on central composite design (RSM-CCD) was used for the ternary system to predict the adsorption efficiency of the REEs and the interactions among different parameters. The kinetic and isotherm models were applied to fit the experimental data of the REEs adsorption in batch system. Besides, the obtained data from column system were fitted by the models.
Las tierras raras (REE) son metales que forman parte componentes utilizados en las nuevas tecnologías. Se utilizan en ingeniería química, imanes permanentes, iluminación fluorescente, sensores, teléfonos celulares, láser, electrónica, baterías recargables, etc., debido a sus propiedades fisicoquímicas únicas. Para suministrar las cantidades requeridas de estos metales y satisfacer sus crecientes demandas, una de las opciones es su recuperación de fuentes secundarias. A pesar de los muchos esfuerzos que se han realizado en este sentido, solo se recicla menos del 1% de REE, debido en parte a problemas como son la recolección de diferentes productos finales y la separación de REE de otros componentes y metales. Entre las diferentes técnicas utilizadas para la separación y purificación de REEs de disoluciones acuosas, la biosorción ha recibido gran atención en las últimas décadas. En este sentido, los biopolímeros se han utilizado ampliamente para el tratamiento de soluciones que contienen metales. El alginato y el quitosano son dos tipos de biopolímeros que han sido utilizados por muchos investigadores debido a que son ecológicos y efectivos. El propósito de este trabajo fue estudiar la adsorción de iones Nd+3, Tb+3 y Dy+3 de disoluciones acuosas mediante el uso de nuevos nanocompuestos magnéticos basados en alginato de calcio (CA) y biopolímeros de carboximetil quitosano (CMC), así como una nueva poliamida sintética biodegradable, la poli (pirimidina-tiofeno-amida) (P (PTA)) y nanopartículas magnéticas (Ni0.2Zn0.2Fe2.6O4). La síntesis de la P(PTA) se realizó en dos etapas. En primer lugar, se sintetizó el monómero de diamina-fenol (TMAPD). En segundo lugar, el polímero se obtuvo por policondensación de TMAPD en el líquido iónico de bromuro de 1,3 -dipropil imidazolio como disolvente, para evitar el uso del trifenilfosfito / N-metilpirrolidona / piridina / LiCl, compuesto tóxico que se requiere en la policondensación directa convencional. Las nanopartículas magnéticas (Ni0.2Zn0.2Fe2.6O4) se sintetizaron mediante la técnica hidrotérmica. Los nanocompuestos magnéticos obtenidos han sido CA/CMC/Ni0.2Zn0.2Fe2.6O4, CA/P(PTA)/Ni0.2Zn0.2Fe2.6O4, y CMC/PPTA)/Ni0.2Zn0.2Fe2.6O4; y se sintetizaron mediante el método de gelación. El compuesto y P(PTA)/Ni0.2Zn0.2Fe2.6O4 se sintetizó mediante el método hidrotérmico. Para la caracterización de los compuestos sintetizados, se utilizaron diferentes técnicas. Para confirmar la formación de Ni0.2Zn0.2Fe2.6O4 y determinar el tamaño de partícula de utilizó XRD. La composición de P(PTA) se confirmó por análisis de RMN. La morfología de Ni0.2Zn0.2Fe2.6O4 y de los nanocompuestos magnéticos se determinó mediante FE-SEM y la estabilidad térmica del P(PTA) y de los nanocompuestos magnéticos, se realizó mediante TGA. EDX se utilizó para el análisis elemental de Ni0.2Zn0.2Fe2.6O4, P(PTA) y de los nanocompuestos magnéticos. El análisis por VSM se aplicó para determinar las propiedades magnéticas del Ni0.2Zn0.2Fe2.6O4 y los nanocompuestos magnéticos, mientras que para la determinación de los grupos funcionales de todos los compuestos se aplicó el análisis FT-IR. Finalmente, se estudió en batch y en columna, la adsorción de Nd+3, Tb+3 y Dy+3 en muestras individuales y ternarias de metales. Para los experimentos en batch, se analizó el efecto de los parámetros principales como el pH, tiempo de contacto, cantidad de adsorbente,concentración inicial, fuerza iónica y temperatura sobre la adsorción de los REE. Además, se determinaron DeltaG', DeltaH', DeltaS' como parámetros termodinámicos. En el sistema ternario, se utilizó la metodología de superficie de respuesta basada en el diseño central compuesto (RSM-CCD) para predecir la eficiencia de adsorción de los REE y las interacciones entre diferentes parámetros. Los datos experimentales de adsorción de REE se ajustaron a modelos de isotermas y cinéticos y de adsorción...

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Oliveira, Marcelo Ferreira Leão de. "Preparação, caracterização e avaliação de nanocompósitos de PBAT/amido de milho e vermiculita organofilizada." Universidade do Estado do Rio de Janeiro, 2015. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=9360.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Nos últimos 20-30 anos polímeros biodegradáveis vêm sendo estudados e desenvolvidos e atualmente já são comercializados. Contudo, o custo, a processabilidade e algumas propriedades ainda dificultam a penetração desses polímeros no mercado e a competição com as chamadas commodities. Não são poucos os autores que se dedicam a desenvolver aditivos e formulações para superar essas limitações. Desta forma, esta Tese se dedicou ao desenvolvimento de compósitos de Ecobras, fabricado pela Basf e comercializado pela Corn Products, utilizando como carga mineral resíduo da extração da bauxita, no município de Santa Luzia/PB, o qual consiste em sua totalidade de vermiculita. Esta vermiculita foi quimicamente modificada com sais de alquil fosfônio para melhorar a compatibilidade com a matriz polimérica e também espaçar as camadas de aluminossilicato. De fato, a modificação com o brometo de hexadecil tributil fosfônio resultou na esfoliação da vermiculita tornando-a potencialmente apropriada para a obtenção de nanocompósitos. A preparação dos compósitos foi realizada pelo método de intercalação no estado fundido e foram comparadas a utilização da câmara interna de mistura e da mini extrusora de dupla rosca, sendo esta última mais eficaz na dispersão da vermiculita, conforme revelado pela microscopia eletrônica de varredura, difração de raios-X e reometria de placas. O grau de dispersão também foi influenciado pela estrutura química do modificador da vermiculita e pelo teor dessa carga incorporada à matriz. Teores mais elevados levaram a formação de aglomerados, enquanto a modificação da carga implicou na formação de micro e nanocompósitos. Ainda houve alterações das propriedades térmicas com aumento dos valores da temperatura de transição vítrea, de cristalização e fusão, embora o grau de cristalinidade tenha sido mantido. Nitidamente, foram obtidos materiais mais rígidos, com maior módulo e menor capacidade de deformação. Cerca de 58% de perda de massa foi observada para os micro e nanocompósitos obtidos após 17 semanas de enterro em solo simulado para avaliação da biodegradabilidade, valor bem próximo ao Ecobras puro. De modo geral, a incorporação das diferentes vermiculitas retardou nas primeiras semanas a biodegradação, provavelmente em função de modificações na estrutura cristalina, conforme sugerido pelos maiores valores de temperatura de fusão observados durante o acompanhamento do processo de biodegradação. No entanto, após 7 semanas os perfis de biodegradação dos micro e nanocompósitos se aproximaram bastante do Ecobras puro. Desta forma, foi possível nesta Tese obter um nanocompósito de Ecobras com vermiculita modificada com brometo de hexadecil fosfônio utilizando ferramentas comuns de processamento no estado fundido com biodegradabilidade próxima ao polímero de partida, porém mais rígido e menos deformável
In the last 20-30 years biodegradable polymers have been studied and developed and currently are already commercialized. However, cost, processability and some properties still avoid the penetration of such polymers on the market and the competition with the so-called commodity. There are few authors who are dedicated to developing additives and formulations to overcome these limitations. Thus, this thesis is devoted to the development of Ecobras composites, blend of PBAT and starch manufactured by BASF and commercialized by Corn Products, using as mineral filler a residue of bauxite extraction from Santa Luzia / PB, which consists entirely of vermiculite. The vermiculite was chemically modified with alkyl phosphonium salts to improve compatibility with the polymer matrix, and also to increase the space between aluminosilicate layers. In fact, its modification with hexadecyl tributyl phosphonium bromide promoted the exfoliation of vermiculite making it potentially suitable for obtaining a nanocomposite. The preparation of the composites was performed by the melt intercalation technique. Internal mixing chamber and a twin screw mini-extruder were compared as processing tool, the latter was more effective in dispersing the vermiculite, as revealed by scanning electron microscopy, X-ray diffraction and plate rheometry. The degree of dispersion was also influenced by the amount and chemical structure of the vermiculite. Higher filler levels led to formation of agglomerates, while filler modification led to formation of micro and nanocomposites. There were changes in the thermal properties with increasing temperature values of glass transition, crystallization and melting, although the degree of crystallinity has been retained. Clearly, stiffer materials were obtained, with a higher modulus and low strain capacity. About 58% of weight loss was observed for micro and nanocomposites after 17 weeks of burial in simulated soil for evaluation of biodegradability, very close to pure Ecobras value. Generally, the incorporation of different vermiculite delayed biodegradation in the first weeks, probably due to changes in crystalline structure as suggested by the higher melting temperature values observed during the monitoring of the biodegradation process. However, after seven weeks of the micro and nanocomposites biodegradation profiles approached quite to pure Ecobras. Thus, it was possible in this work obtain a Ecobras nanocomposite with hexadecyl tetrabutyl phosphonium bromide modified vermiculite prepared by melt intercalation technique using common processing tools and with biodegradability close the starting polymer, but more rigid and less deformable

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Ali, Samer Shaur. "Fundamental interactions and physical properties of starch, poly vinyl alcohol and montmorillonite clay based nanocomposites prepared using solution mixing and melt extrusion." Thesis, Kansas State University, 2010. http://hdl.handle.net/2097/6983.

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Master of Science
Department of Grain Science and Industry
Sajid Alavi
Plastics from petroleum sources are the main raw materials used for producing food packaging films. But these plastic films cause a great environmental concern due to their non-degradable nature and non-renewable source. Biodegradable polymers like starch can be used as a base material which can replace petroleum based plastics packaging. In this study, starch (0-80%) and polyvinyl alcohol (PVOH) (20-100%) were used as base polymers to produce nanocomposites. Glycerol (30%) and sodium montmorillonite (0-20%) were used as a plasticizer and nano-filler, respectively. Nanocomposites were produced through two methods: solution and melt extrusion method. Extrusion method resulted in greater exfoliation of nanocomposites than solution method because it provided more shear stress to disrupt the layered silicate structure. In extrusion method, a lab scale extruder was used to produce these nanocomposites and films were made by casting. Process parameters, including screw speed (200-400 RPM) and barrel temperature (145-165[superscript]oC), were varied systematically. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were conducted to characterize the nanostructure of these nanocomposites. Thermal characterization of these films was carried out through differential scanning calorimetric (DSC) studies. Results from XRD and TEM explained the phenomenon of intercalation and exfoliation in these nanocomposites. Structural and thermal data indicated important role for Na[superscript]+MMT along with process parameters in controlling exfoliation and glass transition temperature of the nanocomposites. These results also helped in understanding the fundamental interactions among all the components. The tensile strength and elongation at break of films ranged from 4.72 to 23.01MPa and 63.40 to 330.15% respectively, while water vapor permeability ranged from 1.68 to 0.79g.mm/kPa.h.m[superscript]2. These results provide a great understanding for further improvements in order to bring these films close to commercial plastic films which have superior tensile strength (10-80MPa), elongation at break (200-800%) and water vapor permeability (0.002- 0.05g.mm/kPa.h.m[superscript]2). The cost for polyethylene is approximately $0.70/lb while the raw material cost for this starch based films is approximately $0.85/lb.

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Molina, Franciele Maria Pelissari. "Production and characterization of biodegradable films of banana starch and flour reinforced with cellulose nanofibers = Produção e caracterização de filmes biodegradáveis de amido e farinha de banana reforçados com nanofibras de celulose." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/256480.

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Orientadores: Florencia Cecilia Menegalli, Paulo José do Amaral Sobral
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
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Resumo: Este trabalho de doutorado teve como objetivo estudar o potencial de uso do amido, farinha e nanofibras obtidos a partir de bananas verdes da variedade Terra (Musa paradisiaca) na elaboração de filmes biodegradáveis. Na primeira etapa do trabalho, o amido e a farinha de banana foram caracterizados quanto às propriedades físicoquímicas, funcionais e térmicas. Ambas as matérias-primas apresentaram considerável conteúdo de amido (94,8 e 83,2%, respectivamente) com alto teor de amilose (35,0 e 23,1%, respectivamente) e amido resistente (49,5 e 50,3%, respectivamente), além de fibras, proteínas e lipídios. Numa segunda etapa, filmes a partir de farinha de banana foram elaborados segundo um planejamento experimental. Os resultados obtidos foram analisados estatisticamente empregando a metodologia de superfície de resposta, que juntamente com a função de desejabilidade permitiu a obtenção da formulação e condições de processo ótimas (concentração de glicerol de 19%, temperatura de processo de 81 ºC, temperatura de secagem de 54 ºC e umidade relativa de 48%). Os filmes produzidos sob essas condições apresentaram tensão na ruptura de 9,2 MPa, elongação de 24,2%, módulo de Young de 583,4 MPa, permeabilidade ao vapor de água de 2,1 x 10-10 g/m.s.Pa e opacidade de 51,3%. Na terceira etapa do trabalho, foram elaborados filmes de farinha e amido de banana para determinar o efeito das fibras, proteínas e lipídios sobre as propriedades dos filmes. O filme de farinha de banana foi mais flexível, solúvel em água e opaco, e menos cristalino e resistente mecanicamente quando comparado com o filme de amido de banana. A partir da microestrutura, observou-se que o filme de farinha apresentou imperfeições na sua superfície e uma seção transversal menos densa com pequenas fissuras quando comparado com o filme de amido. Na quarta etapa, a casca da banana (subproduto do processamento da fruta) foi utilizada como matéria-prima para a obtenção de nanofibras de celulose, empregando tratamento químico e mecânico. A influência do número de passagens (0, 3, 5 e 7) das suspensões em um homogeneizador de alta pressão sobre a estrutura das nanofibras foi estudada. Os tratamentos foram efetivos no isolamento de fibras de banana na escala nanométrica (10,9 - 22,6 nm). Conforme o aumento do número de passagens no homogeneizador, nanofibras de celulose mais estáveis, cristalinas e de menor comprimento foram obtidas. Na última etapa, as nanofibras isoladas foram incorporadas na elaboração de nanocompósitos de amido da mesma fonte. As propriedades desses nanocompósitos foram comparadas com as de um filme de amido sem adição de nanofibras (controle), a fim de estudar o efeito deste reforço. Os nanocompósitos apresentaram uma melhora significativa nas propriedades tensão na ruptura, módulo de Young, resistência à água, opacidade e cristalinidade. Uma homogeneização mais drástica (7 passagens) promoveu a degradação das nanofibras, acarretando numa piora das propriedades do nanocompósito resultante, portanto, a condição de tratamento mecânico mais adequada foi de 5 passagens. As propriedades dos nanocompósitos foram relacionadas com as características físico-químicas das nanofibras incorporadas e também com a boa compatibilidade apresentada entre os biopolímeros amido e nanofibras, uma vez que estes foram obtidos da mesma fonte vegetal
Abstract: This doctor thesis aimed to study the potential use of the starch, flour, and nanofibers obtained from unripe bananas of the variety "Terra" (Musa paradisiaca) to develop biodegradable films. In the first stage of the work, banana starch and flour were characterized on the basis of their physicochemical, functional, and thermal properties. Both raw materials exhibited considerable starch content (94.8 and 83.2%, respectively) with high amylose (35.0 and 23.1%, respectively) and resistant starch (49.5 and 50.3%, respectively), besides fibers, proteins, and lipids. In the second stage, films based on the banana flour were prepared according to an experimental design. The results were statistically analyzed using the response surface methodology which, along with the desirability function, furnished the optimum formulation and process conditions (19% for glycerol concentration, 81 ºC for process temperature, 54 ºC for drying temperature, and 48% for relative humidity). Films produced under these conditions presented tensile strength of 9.2 MPa, elongation at break of 24.2%, Young's modulus of 583.4 MPa, water vapor permeability (WVP) of 2.1 x 10-10 g/m.s.Pa, and opacity of 51.3%. In the third stage of the work, films from banana flour and starch were produced and the effect of fibers, proteins, and lipids on the properties of the flour film was studied. The results showed that the flour film was more flexible, soluble in water and opaque as well as less crystalline and mechanically resistant than the starch film. Compared with the starch film, the microstructure of the flour film has flawed surface, less dense cross-section, and small cracks. In the fourth stage, the banana peel (byproduct from fruit processing) was treated chemically and mechanically, to obtain cellulose nanofibers. The influence of the number of passages (0, 3, 5, and 7) in a high-pressure homogenizer on the structure of the nanofibers was investigated. The treatments were able to isolate the banana fibers in the nanometer scale (10.9 - 22.6 nm). Increasing the number of passages in the homogenizer afforded more stable, more crystalline, and less long cellulose nanofibers. In the last stage, the cellulose nanofibers were incorporated into starch nanocomposites from the same source. The properties of these nanocomposites were compared with those of a starch film without nanofibers (control), in order to study the effect of this reinforcement. The nanocomposites exhibited significantly improved tensile strength, Young's modulus, water resistance, opacity, and crystallinity. A more drastic homogenization (seven passages) degraded the nanofibers, deteriorating the properties of the resulting nanocomposite. Thus, the most suitable mechanical treatment condition involved five passages. The properties of the nanocomposites are a function of the characteristics of the nanofibers, such as crystallinity, zeta potential, and aspect ratio; they also depend on the compatibility between the starch and the nanofibers, which were obtained from the same plant source
Doutorado
Engenharia de Alimentos
Doutora em Engenharia de Alimentos

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Bartolomei, Suellen Signer. "Estudo de nanocompósitos formados por PLA e nanopartículas de celulose." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/3/3133/tde-04072016-152946/.

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Devido à preocupação com o meio ambiente e o volume crescente de resíduos plástico em aterros sanitários, os polímeros biodegradáveis estão sendo estudados extensivamente. Um deles é o PLA. Apesar de possuir propriedades comparáveis a polímeros commodities e polímeros de engenharia, ainda é necessário melhorar certas características do PLA, como resistência ao impacto. Para isso, a nanocelulose (NC) pode ser usada sem alterações significativas na biodegradação polimérica. Este estudo teve como objetivo obter a nanocelulose, caracteriza-la e incorpora-la ao poli(ácido láctico) (PLA), assim como, estudar as propriedades térmicas, morfológicas e mecânicas do compósito obtido. A NC foi obtida por hidrólise ácida utilizando ácido fosfórico e posteriormente foi silanizada com três silanos distintos. As nanopartículas foram caracterizadas por Birrefringência, Microscopia Eletrônica de Transmissão (MET), Termogravimetria (TG), Potencial Zeta, Espectroscopia Vibracional de Absorção no Infravermelho com Transformada de Fourier (FTIR) e Difração de Raio X (DRX). Com as imagens obtidas pelo MET foi possível medir o tamanho das partículas de NC. E então obter a razão de aspecto de 82 e o limite de percolação de 1,1% em massa, confirmando a morfologia de nanofibra. De acordo as analises TG\'s, a presença de NC silanizada aumentou o início da degradação térmica. Os compósitos, contendo 3% em massa de NC, foram obtidos por fusão em câmara de mistura e moldados por injeção. Os compósitos foram caracterizados por FTIR, Cromatografia de Permeação em Gel (GPC), TG, Calorimetria Exploratória Diferencial (DSC), Microscopia Eletrônica de Varredura (MEV-FEG), Impacto e Tração. As análises dos compósitos mostraram que a NC atuou como agente de nucleação, facilitando a cristalização do PLA, além de a NC ter atuado como reforço na matriz polimérica melhorando as propriedades mecânicas.
Due to concern for the environment and the growing volume of plastic waste in landfills, biodegradable polymers are being studied extensively. One of them is the PLA. Despite properties comparable to commodities polymers and engineering polymers, it is still necessary to improve certain characteristics of PLA, such as impact resistance. For this, the nanocelulose (CN) can be used without significant changes on the polymeric biodegradation. This study aimed to obtain nanocelulose, characterizes it and incorporates it to polylactic acid (PLA), even as, studies of thermal, morphological and mechanical properties of the composites processed. The CN was obtained by acid hydrolysis using phosphoric acid and it was, subsequently, silanized with three different silanes. The nanoparticles were characterized by Birefringence, Transmission Electron Microscopy (TEM), Thermogravimetry (TG), Zeta Potential, Spectroscopy Absorption Vibrational Infrared Fourier Transform (FTIR) and X-Ray Diffraction (XRD). By images taken by TEM was possible to measure the size of particles CN. So, obtain the aspect ratio of 82 and the percolation limit of 1.1 wt%, demonstrating morphology of nanofiber. According to TG analysis, the beginning of thermal degradation increased when CN Pure was compared with modified CN. The composite, containing 3 wt% CN, were obtained by melt in mixing chamber and then injection molded. The composites were characterized by FTIR, Gel Permeation Chromatography (GPC), TG, Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM), Impact and Tensile Strength. The results showed that the CN acts as a nucleating agent in PLA, facilitating the crystallization and acts as reinforcement in polymer matrix to improve the mechanical properties.

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Morelli, Carolina Lipparelli. "Développement et étude des propriétés des films et des pièces injectées de nano-biocomposites de nanowhiskers de cellulose et de polymères biodégradables." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENI018/document.

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Notre travail a pour objectif l'étude de l'influence de l'ajout de nanocristaux de cellulose dans des matrices biodégradables sur leurs propriétés. Des films composites et des pièces injectées ont été préparés et caractérisés. Dans ce but, ont été choisis comme matrices le poly(acide lactique), PLA, et le poly (butylène adipate-co-téréphtalate)), PBAT. Deux matières première d'où des nanocristaux de celulose ont été extraites ont été sélectionnées : le bois balse et la cellulose microcrystalline (CMC). En raison du caractère fortement polaire des nanocristaux de cellulose différentes voies de modifications chimiques de la surface de ces particules ont été testées afin d'assurer une bonne dispersion de ceux-ci lorsqu'ils sont ajoutés à des matrices polymères de polarité inférieure. En effet, les approches testées étaient: (a) le greffage de deux types d'isocyanates, dont l'un aliphatique et l'autre aromatique: l'octadécyl isocyanate (NCC_oct) et le phényl-butyle isocyanate (NCC_fb), respectivement; (b) le greffage de poly(butylène glutarate) à travers la technique de polymérisation in situ (NCC_PBG); (c) le greffage de l'acide polyacrylique à travers la technique appelée click chemistry (NCC_PA); et (d) la silanisation avec le - methacryloxy-propyle-trimethoxy-silane(NCC_MPS). Les NCCs initiaux et modifiés ont été ajoutés aux matrices de PBAT ou du PLA par procédés de mélanges à partir de solution (casting) ou à partir de l'état fondu (par extrusion ou en utilisent un homogénisateur de type Drais). En général, la modification chimique de la surface de NCC a augmenté la résistance thermique de celui-ci, a diminué son caractère hydrophile et a amélioré la dispersion des NCCs dans les matrices de PLA et PBAT. Cela a provoqué des augmentations encore plus grandes dans les propriétés de ces polymères, en fonction du type de modification et du procédé de fabrication utilisé. La caractérisation des nanocomposites a démontré que, en général, l'addition des NCCs a augmenté le module d'élasticité de la matrice et a conservé sa rigidité même à températures relativement élevées. Des niveaux plus élevés de NCC conduisent à de plus grandes augmentations de la rigidité. La perméabilité à la vapeur d'eau de PBAT a été réduite par l'introduction de NCC et n'a pas changé dans le cas du PLA. Les résullts de ces travaux ont indiqué de bonnes perspectives concernant l'utilisation des nanocristaux de cellulose comme élément de renfort de matrices polymères. De manière générale, le présent travail a démontré que les NCCs étaient capables d'améliorer les propriétés mécaniques, thermiques et de barrières du PBAT et du PLA, qui sont deux polymères biodégradables largement utilisés dans les applications de films ou de pièces plastiques. De plus, les résultats montrent qu'il est possible de modifier la polarité des NCC en les soumettant à des modifications chimiques de surface afin d'éviter leur agglomération par la formation de ponts de liaisons hydrogènes et de les rendre compatibles avec différentes matrices polymères. Ces modifications chimiques tendent aussi à élever la résistance thermique des NCCs. De cette manière, les procédés à l'échelle industrielle comme l'extrusion et l'injection peuvent être utilisés et fournissent de bons résultats
This study aimed at evaluating the potential of application of cellulose nanocrystals as reinforcing elements of biodegradable polymeric matrices, in the films and injection molded pieces applications. Two polymeric matrices with different properties were used, namely: poly(butylene adipate-co-terephthalate), PBAT, and poly(lactic acid), PLA. For the extraction of cellulose nanocrystals (NCC), two sources were selected: microcrystalline cellulose (CMC) and balsa wood . Due to the high polarity of cellulose nanocrystals, different approaches of surface chemical modifications of these particles were tested, in order to ensure their good dispersion when added to polymeric matrices of lower polarity. They were: a) chemical modification with two types of isocyanates, an aliphatic one (octadecyl isocyanate) and an aromatic one (phenylbutyl isocyanate); b) grafting of poly (butylene glutarate) using the in situ polymerization technique; c) silanization treatment; and d) grafting of poly(acrylic acid) through click chemistry technique. Modified and unmodified NCCs were processed with PBAT and PLA by casting or melt extrusion processing techniques. In general, the chemical modification of NCC surface increased their thermal resistance, decreased their polarity and improved their dispersion into PLA and PBAT matrices. Some of these treatments, as well as the processing conditions enabled an increase in the overall mechanical properties of the polymers. Thus, the characterization of the nanocomposites showed that NCC addition increased the elastic modulus of the matrix and retained its higher stiffness even under relatively high temperatures. Higher NCC contents led to larger increases in the stiffness of the ensuing composites. The water vapor permeability of PBAT was also reduced with the introduction of NCC. This work points out several potential good perspectives for the use of celulose nanocrystals as reinforcing elements of polymeric matrices. It showed also that it is possible to obtain significant improvements in the polymer properties using the same processing techniques as those used at industrial scale, such as melt extrusion and injection molding
O presente estudo de doutorado teve como objetivo avaliar o potencial deaplicação de nanocristais de celulose como reforço em matrizes poliméricasbiodegradáveis, em aplicações de filmes ou em peças moldadas por injeção.Duas matrizes poliméricas de diferentes propriedades foram utilizadas paraestudo nessas aplicações, sendo elas: poli(butileno adipato-co-tereftalato),PBAT, e poli(ácido láctico), PLA. Foram também selecionadas duas fontes paraextração dos nanocristais de celulose (NCC): a celulose microcristalina (CMC)e a madeira balsa.Devido ao caráter altamente polar dos nanocristais de celulose diferentesrotas de modificações químicas superficiais dessas partículas foram testadas,visando garantir a boa dispersão dos mesmos quando adicionados às matrizespoliméricas de menor polaridade. Foram elas: a) modificação química com doistipos de isocianatos, sendo um de cadeia alifática (octadecil isocianato) e outrode cadeia aromática (fenilbutil isocianato); b) enxertia do poli(butileno glutarato)através da técnica de polimerização in situ; c) tratamento de silanização com -metacriloxi-propil-trimetoxi-silano; d) enxertia de poli(ácido acrílico) através datécnica de click chemistry.NCC modificados e não modificados foram processados com PBAT ouPLA através de mistura com o polímero em solução (casting) ou no estadofundido (extrusão ou homogeneizador de alta rotação do tipo Drais).De modo geral, modificações químicas superficiais dos NCC aumentarama estabilidade térmica dos mesmos, diminuíram sua polaridade e melhoraram adispersão dos NCC nas matrizes de PBAT ou PLA. Isso fez com queincrementos ainda maiores nas propriedades desses polímeros pudessem serxxivalcançados, dependendo do tipo de modificação e do processo de misturautilizados.A caracterização dos nanocompósitos obtidos mostrou que a adição deNCC elevou o módulo elástico das matrizes e conservou sua maior rigidezmesmo em temperaturas relativamente elevadas, sendo que maiores teores deNCC levaram a maiores aumentos na rigidez. A permeabilidade a vapor deágua do PBAT também foi reduzida com a introdução dos NCC e não foialterada no caso do PLA.Os resultados desse trabalho apontaram boas perspectivas no uso dosnanocristais de celulose como reforços de matrizes poliméricas. Tambémmostraram que é possível obter melhorias nas propriedades de polímerosmesmo através da utilização de processos de maior reprodutibilidade emescala industrial, como extrusão e injeção

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Nordqvist, David. "Biodegradable nanocomposite films based on amylopectin and chitosan /." Stockholm, Department of Fibre and Polymer Technology, Royal Institute of Technology, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4168.

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21

Chevillard, Anne. "Materiaux nanocomposites biodegradables pour la liberation controlee de pesticides." Thesis, Montpellier 2, 2011. http://www.theses.fr/2011MON20114/document.

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L'objectif de cette thèse était de développer des matériaux biodégradables (nano-)composites à libération contrôlée de pesticides, afin d'améliorer leur efficacité et limiter leurs impacts sur l'environnement (pertes par lessivage, dégradation etc.). La stratégie a consisté à réaliser par extrusion des matériaux à base de gluten de blé et de nanoparticules d'argile pour moduler la libération d'un herbicide modèle (l'éthofumesate) introduit dans la matrice. Combinée au gluten, l'utilisation d'argiles vise à moduler les propriétés de transfert de matière en jouant 1/sur des phénomènes de sorption (affinité entre pesticide et argiles), et 2/sur des phénomènes de diffusion (structure des composites gluten/argiles). Cette étude a soulevé différentes questions scientifiques : • Identifier les mécanismes impliqués dans les phénomènes de sorption et de désorption de l'éthofumesate sur différentes argiles • Comprendre comment la présence des nanoparticules d'argiles dans une matrice de gluten de blé pouvait induire des changements de propriétés du matériau telles que la sensibilité à l'eau et la vitesse de biodégradation, en lien avec les modifications structurales. • Identifier le déterminisme des modifications des propriétés de transfert de l'éthofumesate dans les « matériaux complets » (gluten-nanoparticules d'argiles-éthofumesate) dans des systèmes modèles et en conditions réelles (sol agricole).C'est grâce à une démarche intégrée, associant des outils d'étude appartenant à des domaines de compétences complémentaires comme la science des matériaux, les matériaux nanocomposites, l'agronomie, la formulation de pesticides et la modélisation des propriétés de transfert, qu'il a été possible de répondre aux différents objectifs scientifiques. Cette étude contribue ainsi à une meilleure compréhension des mécanismes de transfert de composés d'intérêt au sein de matériaux à base d'agropolymères en présence de nanoparticules d'argile. Elle a notamment permis de pondérer l'importance de la structure nanocomposite, par rapport aux phénomènes de sorption, lorsqu'on s'intéresse à la modulation des propriétés de transfert au sein d'un matériau
The objectives of this study were to develop (nano)composite biodegradable materials for the controlled delivery of pesticides with the aim being to improve their efficiency and limit their negative impacts on the environment (due to leaching, degradation etc.). Our strategy has consisted in using an extrusion process to design materials based on wheat gluten and clay nanoparticules in order to fine tune the release of a model herbicide (ethofumesate) introduced into the matrix. Combined with gluten, the use of nanoclays aims to modulate transfer properties by acting on 1/ sorption phenomenon (driven by pesticide/clay affinity), and 2/diffusion phenomenon (depending on wheat gluten/clay structure). This study has led to different scientific questions : • Identify mechanisms involved in sorption/desorption behaviour of ethofumesate on different clays • Understand how the presence of nanoclays in a wheat gluten matrix was able to induce changes in material properties such as water sensitivity and biodegradation rate, in relation to structural changes • Identify the determinism of these changes in transfer properties in the case of the finished materials containing wheat gluten/nanoclay/ethofumesate, both in model medium and in real conditions (soil)Responding to these different scientific objectives has been possible using an integrated approach, combining tools of complementary skill fields such as material science, nanocomposite materials, agronomy, pesticide formulation and transfer modeling properties This study contributes to a better understanding of transfer properties of interesting compounds in the case of agropolymer based materials containing or filled with nanoclays. This work has notably enabled to balance the importance given at the nancomposite structure contribution in relation to sorption phenomenon in a context where the objective is to modulate material transfer properties

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22

Garikapati, Anusha. "Cytotoxicity of biodegradable magnetic nanocomposite spheres for drug delivery purposes." Thesis, Wichita State University, 2010. http://hdl.handle.net/10057/3307.

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The use of nanotechnology is growing rapidly, with potential applications ranging from production to electronics to medicine. Nanotechnology has been proven to have a great impact on biomedicine through its applications in tissue engineering, cancer therapy, hyperthermia, and other drug delivery purposes. Nanomaterials can be fabricated and manipulated to suit the requirements for a particular function. Drug delivery through magnetic nanoparticles is being used for site-specific and controlled drug-release purposes. Magnetic drug transport involves encapsulating a drug in a magnetic nanosphere and administering it intravenously to deliver it to a particular organ or a receptor for therapeutic purposes. Nanotechnology-based drug delivery maximizes patient compliance and targeting efficiency, and thus reduces the toxicity of the drug to normal cells. Nanotechnologies that are being used in medical applications for diagnostics, as drug carriers, and for prosthesis and implants have raised interest and concern about their biocompatibility and toxicity. It has been shown that nanomaterials that come in contact with the human body can affect the central nervous system and cause inflammatory responses in the lungs, liver, spleen, etc. In this research, emphasis was placed on determining the toxicity of nanocomposite spheres made from two magnetic nanoparticles—nickel ferrite and cobalt ferrite. These magnetic nanoparticles were fabricated using a sol-gel process and then used to fabricate nanocomposite spheres using PLGA as a polymer and an oil-in-oil emulsion/solvent evaporation technique. Different samples were made with different nanoparticle compositions, and these samples were tested for cytotoxicity using a standard colorimetric test using MTT assay. Viability tests were conducted on these cells to determine the toxicity by varying the composition and concentration of the nanoparticle, and then comparing the two different nanomaterials.
Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering.

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Piao, Haiyuan. "Microbial-derived cellulose-reinforced biocomposites." Thesis, University of Canterbury. Mechanical Engineering, 2006. http://hdl.handle.net/10092/1139.

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The preparation and characterisation of novel nano-scale biodegradable biocomposite materials, consisting of bacterial cellulose (BC) in a poly(lactic acid) (PLA) matrix, are investigated. BC exhibits high purity, high mechanical strength and an ultra-fine fibrous 3D network structure, while PLA is low cost, biodegradable matrix material derived from natural resources. In this work, composites of BC reinforced PLA were prepared using a solution exchange process and compression molding. The microstructure of the raw materials and composites was characterised using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM). The thermal properties and crystallinity of PLA and composites were measured using differential scanning calorimetry (DSC). The mechanical properties of pure PLA and composite materials were evaluated using static and dynamic mechanical analysis (DMA). In order to improve the interfacial adhesion between the BC and PLA matrix, BC was acetylated (ABC) or treated with 3-aminopropyltriethoxysilane (APS) coupling agent (SBC). The PLA was plasticized with glycerol (PLAG) in order to increase its ductility. As compared to the Young's modulus of neat PLA (1.9 GPa), ABC generated the highest increase in Young's modulus (4.8 GPa) of the resulting composites followed by BC (4.6 GPa) and SBC (4.5 GPa). The tensile strength of PLA (31 MPa) also was enhanced to 75 MPa with BC, 72 MPa with SBC or 38 MPa with ABC. The ductility of PLAG was degraded with the addition of glycerol. A large amount voids led to a reduction in the mechanical properties of PLAG and PLAG based composites. Every reinforcement led to an improvement in the storage modulus (E') of the neat PLA and PLAG, especially at temperatures above the glass transition temperature (Tg). The DMA results showed that the presence of BC based reinforcements significantly reduced the damping properties of PLA. The reinforcements also influenced the crystalline procedure of PLA. With the addition of BC or ABC to the PLA matrix, the melting points of the composites were increased ~ 4-7 ℃ with a slight change on crystallinity; the crystallinity of SBC-PLA composite decreased from 31.9 % to 26.9 % with only a change of ~ 1 ℃ in the melting point.

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Hawkins, Ashley Marie. "BIODEGRADABLE HYDROGELS AND NANOCOMPOSITE POLYMERS: SYNTHESIS AND CHARACTERIZATION FOR BIOMEDICAL APPLICATIONS." UKnowledge, 2012. http://uknowledge.uky.edu/cme_etds/10.

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Hydrogels are popular materials for biological applications since they exhibit properties like that of natural soft tissue and have tunable properties. Biodegradable hydrogels provide an added advantage in that they degrade in an aqueous environment thereby avoiding the need for removal after the useful lifetime. In this work, we investigated poly(β-amino ester) (PBAE) biodegradable hydrogel systems. To begin, the factors affecting the macromer synthesis procedure were studied to optimize the reproducibility of the resulting hydrogels made and create new methods of tuning the properties. Hydrogel behavior was then tuned by altering the hydrophilic/hydrophobic balance of the chemicals used in the synthesis to develop systems with linear and two-phase degradation profiles. The goal of the research was to better understand methods of controlling hydrogel properties to develop systems for several biomedical applications. Several systems with a range of properties were synthesized, and their in vitro behavior was characterized (degradation, mechanical properties, cellular response, etc.). From these studies, materials were chosen to serve as porogen materials and an outer matrix material to create a composite scaffold for tissue engineering. In most cases, a porous three dimensional scaffold is ideal for cellular growth and infiltration. In this work, a composite with a slow degrading outer matrix PBAE with fast degrading PBAE microparticles was created. First, a procedure for developing porogen particles of controlled size from a fast-degrading hydrogel material was developed. Porogen particles were then entrapped in the outer hydrogel matrix during polymerization. The resulting composite systems were degraded and the viability of these systems as tissue engineering scaffolds was studied. In a second area of work, two polymer systems, one PBAE hydrogel and one sol-gel material were altered through the addition of iron oxide nanoparticles to create materials with remote controlled properties. Iron oxide nanoparticles have the ability to heat in an alternating magnetic field due to the relaxation processes. The incorporation of these nanoscale heating sources into thermosensitive polymer systems allowed remote actuation of the physical properties. These materials would be ideal for use in applications where the system can be changed externally such as in remote controlled drug delivery.

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Sullivan, Erin M. "Understanding the process-structure-property relationship in biodegradable polymer nanocomposite films." Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/54428.

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The focus of this study was to explore process-structure-property relationships in biodegradable polymer nanocomposite films in order to eliminate the commonly used trial and error approach to materials design and to enable manufacturing of composites with tailored properties for targeted applications. The nanofiller type and concentration, manufacturing method and compounding technique, as well as processing conditions were systematically altered in order to study the process-structure-property relationships. Polylactic acid (PLA) was used as the polymer and exfoliated graphite nanoplatelets (GNP), carbon nanotubes (CNT), and cellulose nanocrystals (CNC) were used as reinforcement. The nanocomposite films were fabricated using three different methods: 1) melt compounding and melt fiber spinning followed by compression molding, 2) solution mixing and solvent casting, and 3) solution mixing and electrospinning followed by compression molding. Furthermore, the physical properties of the polymer, namely the crystallization characteristics were altered by using two different cooling rates during compression molding. The electrical response of the composite films was examined using impedance spectroscopy and it was shown that by altering the physical properties of the insulating polymer matrix, increasing degree of crystallinity, the percolation threshold of the GNP/PLA films is significantly reduced. Additionally, design of experiments was used to examine the influence of nanofiller type (CNT versus GNP), nanofiller content, and processing conditions (cooling rate during compression molding) on the elastic modulus of the composite films and it was concluded that the cooling rate is the primary factor influencing the elastic modulus of both melt compounded CNT/PLA and GNP/PLA films. Furthermore, the effect of nanofiller geometry and compounding method was examined and it was shown that the high nanofiller aspect ratio in the CNT/PLA films led to decreased percolation threshold compared to the GNP/PLA films. The melt compounded GNP/PLA films displayed a lower percolation threshold than the solution cast GNP/PLA films most likely due to the more homogeneous distribution and dispersion of GNP in the solution cast films. Fully biodegradable and biorenewable nanocomposite films were fabricated and examined through the incorporation of CNC in PLA. Through the addition of CNC, the degree of crystallinity of the matrix was significantly increased. Focusing the design space through investigation of process-structure-property relationships in PLA nanocomposites, can help facilitate nanocomposites with tailored properties for targeted applications.

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Morelli, Carolina Lipparelli. "Processamento e estudo das propriedades de filmes e peças injetadas de nanobiocompósitos de nanocristais de celulose e matrizes biodegradáveis." Universidade Federal de São Carlos, 2014. https://repositorio.ufscar.br/handle/ufscar/721.

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This study aimed at evaluating the potential of application of cellulose nanocrystals as reinforcing elements of biodegradable polymeric matrices, in the films and injection molded pieces applications. Two polymeric matrices with different properties were used, namely: poly(butylene adipate-co-terephthalate), PBAT, and poly(lactic acid), PLA. For the extraction of cellulose nanocrystals (NCC), two sources were selected: microcrystalline cellulose (CMC) and balsa wood . Due to the high polarity of cellulose nanocrystals, different approaches of surface chemical modifications of these particles were tested, in order to ensure their good dispersion when added to polymeric matrices of lower polarity. They were: a) chemical modification with two types of isocyanates, an aliphatic one (octadecyl isocyanate) and an aromatic one (phenylbutyl isocyanate); b) grafting of poly (butylene glutarate) using the in situ polymerization technique; c) silanization treatment; and d) grafting of poly(acrylic acid) through click chemistry technique. Modified and unmodified NCCs were processed with PBAT and PLA by casting or melt extrusion processing techniques. In general, the chemical modification of NCC surface increased their thermal resistance, decreased their polarity and improved their dispersion into PLA and PBAT matrices. Some of these treatments, as well as the processing conditions enabled an increase in the overall mechanical properties of the polymers. Thus, the characterization of the nanocomposites showed that NCC addition increased the elastic modulus of the matrix and retained its higher stiffness even under relatively high temperatures. Higher NCC contents led to larger increases in the stiffness of the ensuing composites. The water vapor permeability of PBAT was also reduced with the introduction of NCC. This work points out several potential good perspectives for the use of celulose nanocrystals as reinforcing elements of polymeric matrices. It showed also that it is possible to obtain significant improvements in the polymer properties using the same processing techniques as those used at industrial scale, such as melt extrusion and injection molding.
O presente estudo de doutorado teve como objetivo avaliar o potencial de aplicação de nanocristais de celulose como reforço em matrizes poliméricas biodegradáveis, em aplicações de filmes ou em peças moldadas por injeção. Duas matrizes poliméricas de diferentes propriedades foram utilizadas para estudo nessas aplicações, sendo elas: poli(butileno adipato-co-tereftalato), PBAT, e poli(ácido láctico), PLA. Foram também selecionadas duas fontes para extração dos nanocristais de celulose (NCC): a celulose microcristalina (CMC) e a madeira balsa. Devido ao caráter altamente polar dos nanocristais de celulose diferentes rotas de modificações químicas superficiais dessas partículas foram testadas, visando garantir a boa dispersão dos mesmos quando adicionados às matrizes poliméricas de menor polaridade. Foram elas: a) modificação química com dois tipos de isocianatos, sendo um de cadeia alifática (octadecil isocianato) e outro de cadeia aromática (fenilbutil isocianato); b) enxertia do poli(butileno glutarato) através da técnica de polimerização in situ; c) tratamento de silanização com - metacriloxi-propil-trimetoxi-silano; d) enxertia de poli(ácido acrílico) através da técnica de click chemistry. NCC modificados e não modificados foram processados com PBAT ou PLA através de mistura com o polímero em solução (casting) ou no estado fundido (extrusão ou homogeneizador de alta rotação do tipo Drais). De modo geral, modificações químicas superficiais dos NCC aumentaram a estabilidade térmica dos mesmos, diminuíram sua polaridade e melhoraram a dispersão dos NCC nas matrizes de PBAT ou PLA. Isso fez com que incrementos ainda maiores nas propriedades desses polímeros pudessem ser alcançados, dependendo do tipo de modificação e do processo de mistura utilizados. A caracterização dos nanocompósitos obtidos mostrou que a adição de NCC elevou o módulo elástico das matrizes e conservou sua maior rigidez mesmo em temperaturas relativamente elevadas, sendo que maiores teores de NCC levaram a maiores aumentos na rigidez. A permeabilidade a vapor de água do PBAT também foi reduzida com a introdução dos NCC e não foi alterada no caso do PLA. Os resultados desse trabalho apontaram boas perspectivas no uso dos nanocristais de celulose como reforços de matrizes poliméricas. Também mostraram que é possível obter melhorias nas propriedades de polímeros mesmo através da utilização de processos de maior reprodutibilidade em escala industrial, como extrusão e injeção.

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Yildirimer, E. L. "A novel biodegradable poly(ε-caprolactone urea)urethane incorporating polyhedral oligomeric silsesquioxane nanocomposite and applications for skin tissue engineering." Thesis, University College London (University of London), 2014. http://discovery.ucl.ac.uk/1437739/.

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Skin protects our bodies for a lifetime and extensive loss of this barrier renders the individual susceptible to infections and death. Clinically available treatment options, however, are limited in establishing both functional and cosmetic satisfaction. The work described in this thesis is therefore concerned with the development and characterization of a novel biodegradable nanocomposite system displaying suitable properties as skin tissue engineering scaffolds. A novel family of segmented polyurethanes (PU) with increasing hard segment content based on a poly(ε-caprolactone urea)urethane backbone incorporating POSS nanoparticles was synthesized and analysed in terms of material characteristics and biocompatibility. Incorporation of POSS nanoparticles into the PU backbone yielded mostly amorphous materials as corroborated by distinct glass transitions visible on differential scanning calorimetry spectra. With incrementally increasing hard segment content, ultimate tensile strength increased from ~10 to 21 MPa accompanied by increased values for elastic moduli from 0.03 to 0.06 MPa. Number average molecular weights (Mn) decreased with increasing hard segment content due to a corresponding decrease in the proportion of PCL. Sterilization studies raised fundamental concerns regarding the suitability of conventionally available techniques since hydrolytically and temperature labile polymers are susceptible to degradation. The results obtained suggest 70 % ethanol to be a suitable laboratory-based disinfectant which was further demonstrated to have favourable effects on skin cell compatibility. Degradation studies revealed hard segment-dependent modulation of the degradation rate and the materials’ viscoelasticity. In vivo implantation studies of porous scaffolds demonstrated firm integration with the subcutaneous tissue and extensive vascularization. The results obtained in this work highlight (i) the ability to control scaffold degradation rates and mechanical properties and (ii) cellular as well as in vivo biocompatibility, all of which fundamental in the development of a versatile skin tissue engineering scaffold.

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Dee, Ryan Joseph. "The examination of a biodegradable nanocomposite polymer and decellularised blood vessels as scaffold materials for tissue engineered vascular grafts in the paediatric patient." Thesis, University College London (University of London), 2018. http://discovery.ucl.ac.uk/10042126/.

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There is a need for TEVG for surgical use in paediatric cases of vascular and congenital heart defects. Two materials were tested for the suitability as the basis of a tissue engineered vascular graft: a synthetic biodegradable nanocomposite polymer developed at Royal Free Hospital, polyhedral oligmeric silsesquioxane poly(caprolactone-urea) urethane (POSS-PCLUU); and umbilical vessels and rat aorta decellularised by Detergent Enzymatic Treatment (DET). Phase inversion with NaHCO3 porogen leaching was employed to fabricate porous POSS-PCLUU foams. Changing the concentration of NaHCO3 porogen was examined for its effect on bulk and surface properties and a concentration of 45% NaHCO3 porogen was selected for the extrusion of porous grafts. The mechanical and structural properties of grafts extruded using different sized NaHCO3 porogen particles at a concentration of 45% were investigated and a particle size of 60 μm was considered to be most appropriate. The maximum burst pressure was 238 mmHg and aneurysm formation was observed before graft failure. DET decellularisation removed a significant amount of DNA from human umbilical cord artery and vein, as well as rat aorta. The structure and mechanical strength of the vessels was maintained after decellularisation. Decellularised umbilical artery had a burst pressure of 831 mmHg and no aneurysm formation was observed. There was a large reduction in the extracellular proteins elastin and glycosaminogylcans (GAG). Human Umbilical Vein Endothelial Cells (HUVEC), Amniotic Fluid Stem Cells (AFSC) were seeded on to aliphatic POSS-PCLUU fabricated with 45% 60 μm NaHCO3 porogen. AFSC performed poorly in comparison to HUVEC. HUVEC had a large coverage of cells in the first few days post seeding but this dropped significantly after 7 days. HUVEC and AFSC both formed large clusters of cells when seeded on decellularised rat aorta. In conclusion, the POSS-PCLUU, DET decellularised umbilical vessels and rat aorta would not be suitable as a material for TEVG due to poor mechanical properties and scaffold-cell interaction.

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Cordeiro, Edna Maria Silva. "Biocomp?sitos polim?ricos obtidos a partir da fra??o lignocelul?sica e amil?cea do caro?o de manga (mangifera indica), Tommy atkins." Universidade Federal do Rio Grande do Norte, 2013. http://repositorio.ufrn.br:8080/jspui/handle/123456789/12827.

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This employment has the function the utilization of mango seeds Tommy Atkins, like starch source to obtain biopolymers and fibers source and nanowhiskers cellulose also, that will be use like reinforcing fillers in micro and nanobiocomposites polymeric. The fibers in natura removed from tegument mango seed were characterized, as weel as the treated fibers and nanowhiskers of cellulose extracted from them. The starch extracted from seed s almond showed a good performance (32%) and a high purity. The chemicals analyzes, of crystallinity and morphological of the fibers in natura, treated fibers and nanowhiskers of cellulose confirmed the efficacy of the chemical treatement performed to remove amorphous constituents (hemicellulose and lignina). The thermoplastic starch (TPS) obtained from two sources, corn starch and starchy material mango, was produced in a twin screw extruder with compositon mass of 62,5% of starch, 9,4% of water and 28,1% of glycerol. The starch material mango was the main objective of this work for the production of biodegradable materials, and the starch corn was utilized during the production stage to evaluate the processability of the starch and use as parameter for comparison, according of being a conventional source for obtaining conventional comercial starch. The incorporation of fibers (6% in mass) and nanowhiskers cellulose (1% in mass) in matrix of TPS to obtain composite and nanocomposite, respectively, it was performed in single screw extruder. The biocomposites and bionanocomposites polymeric were obtained and the TPS from starchy material mango presented better results of thermal and mechanicals properties when compared to TPS corn starch. Concludes that the sediment generated of the agroindustrial processing mango used presents potencial to producing of biodegradables materials
Este trabalho apresenta como objetivo a utiliza??o de caro?os da manga Tommy Atkins, como fonte de amido para obten??o de biopol?meros e, tamb?m, como fonte de fibras e nanowhiskers de celulose, que foram utilizadas como cargas refor?antes em micro e nanobiocomp?sitos polim?ricos. As fibras in natura removidas do tegumento do caro?o de manga foram caracterizadas, bem como as fibras tratadas e nanowhiskers de celulose extra?dos a partir delas. O amido extra?do das am?ndoas do caro?o apresentou um bom rendimento (32%) e elevado grau de pureza. As an?lises qu?micas, de cristalinidade e morfol?gicas das fibras in natura, fibras tratadas e nanowhiskers de celulose confirmaram a efic?cia do tratamento qu?mico realizado em remover os constituintes amorfos (hemicelulose e lignina). O amido termopl?stico (TPS) obtido de duas fontes, amido de milho e material amil?ceo de manga, foi produzido em extrusora rosca dupla com a composi??o em massa de 62,5% de amido, 9,4% de ?gua e 28,1% de glicerol. O material amil?ceo de manga foi o objetivo principal deste trabalho para produ??o de materiais biodegrad?veis, e o amido de milho foi utilizado durante a etapa de produ??o para avaliar a processabilidade do amido e utilizar como par?metro de compara??o, em fun??o de ser uma fonte convencional de obten??o de amido comercial. A incorpora??o das fibras (6% em massa) e nanowhiskers de celulose (1% em massa) em matriz de TPS para obter comp?sitos e nanocomp?sitos, respectivamente, foi realizada em extrusora monorosca. Os biocomp?sitos e bionanocomp?sitos polim?ricos foram obtidos e os TPS do material amil?ceo de manga apresentaram melhores resultados de propriedades t?rmicas e mec?nicas quando comparados aos TPS de amido de milho. Concluiu-se que os res?duos gerados do processamento agroindustrial da manga utilizados apresentaram potencial para a produ??o de materiais biodegrad?veis

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Xu, Mo. "Development of Lightweight, Biodegradable Plastic Foam Fibres with Poly (Lactic) Acid-clay Nanocomposites." Thesis, 2013. http://hdl.handle.net/1807/43345.

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Polymeric fibres influence our everyday life in numerous aspects; the area of applications ranges from industrial to everyday commodities, textile and non-textile. As the global demand for the polymeric fibres increases rapidly, new innovative classes of fibres and the manufacturing processes are sought after. This thesis develops an approach to produce fine cell structure and low void fraction foams, which is then used in the manufacturing of lightweight, biodegradable foam fibres. Poly (lactic) acid-clay nanocomposite have been foamed with nitrogen and drawn to different melt draw ratio to produce foam fibres. The foam fibres are then characterized for crystallinity, Young’s modulus and the yield stress. While the drawability of foam has been demonstrated, the crystallinity as well as the mechanical properties of the foam fibres are not drastically enhanced by drawing, as would be expected. Further drawing processes of the as-spun foam fibres are recommended.

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31

Lin, Wan-Ying, and 林宛螢. "The Preparation and Properties of Biodegradable PLA/Modified Multi-Walled Carbon Nanotubes Nanocomposites." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/69237979827704459428.

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碩士
朝陽科技大學
應用化學系碩士班
98
In this study, polylactic acid / pristine carbon nanotubes or modified carbon nanotubes nanocomposites were prepared by a melt blending method. In order to increase the compatibility between multi-walled carbon nanotubes (CNTs) and polylactic acid (PLA), the surfaces of CNTs were chemically modified. In this study, CNTs were first pre-treated using acid solution (HNO3) to functionalize the CNTs surface with carboxylic groups (-COOH), form the acid-treated carbon nanotubes (CNT-COOH). Subsequently, the stearyl alcohol was grafted onto carboxylic groups with the assistance of dehydrating agent, N,N’-dicyclohexyl-carbodiimide (DCC), then we can obtain the modified CNTs (CNT-C18). The CNT-C18 can be dispersed in organic solvents, such as DMF, THF, and chloroform. Furthermore, the modified carbon nanotubes and PLA were mixed by solution method, and a small amount of ester-exchange agent was added, so that modified carbon nanotubes can be grafted onto PLA chains to enhance mechanical and physical properties of the composites. Finally, the PLA/CNTs nanocomposites were then prepared through melt-blending method. The thermal behaviors, morphology, mechanical properties, conductivity of resultant PLA/CNTs nanocomposites were investigated. The results show that excellent dispersion of nanotubes in the PLA matrices was achieved. Moreover, an improvement in thermal properties was also observed. Nanocomposite with the addition of 3wt% modified carbon nanotubes and ester-exchange agent modified carbon nanotubes composites, the increments of storage modulus (E'') at 40oC were 77.4% and 88.0%, respectively. And the increments of loss modulus (E'') at glass transition temperature (Tg) were 43.8% and 75.6%, respectively. In the aspect of conductivity, the surface resistivity of the PLA nanocomposites decreased from 5.30×1012 Ω/cm2 to 8.58×10-2 Ω/cm2 after addition of 3wt% ester-exchange agent modified carbon nanotubes. Such modified carbon nanotubes nanocomposites are highly efficient for anti-static purpose, even electrostatic discharge or anti-EMI purpose, which can be applied in electronic materials.

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32

Wu, Chen-zhe, and 吳臣哲. "Biodegradable poly(butylene succinate) and its copolyesters with minor amounts of propylene succinate/montmorillonite nanocomposites." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/fthz49.

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碩士
國立中山大學
材料與光電科學學系研究所
103
In this study, biodegradable nanocomposites were prepared. In order to improve the compatibility between polymer and montmorillonite (MMT), the surface of MMT was organo-modified by disodium cocoamphdipropionate (K2). Then, poly(butylene succinate) (PBSu) and its copolyesters with minor amount of propylene succinate (PBPSu90/10, PBPSu80/20) were blended with 1, 3, or 5 wt% of MMT-K2, respectively, by the melt intercalation. The physical properties of these biodegradable nanocomposites were characterized before studying their crystallization and melting behaviors. The Fourier Transform Infrared spectrum and wide-angle X-ray diffraction (WAXD) pattern show that MMT was successfully modified with K2, and the interlayer distance of MMT was increased from 1.62 to 3.94 nm. The WAXD patterns of nanocomposites yield that the interlayer distance of MMT-K2 was higher than 5.94 nm. The micrographs of transmission electron microscope indicate that these nanocomposites were intercalated, not exfoliated. The results of thermogravimetric analysis revealed that the thermal stability of the resultant nanocomposites was reduced after the addition of MMT-K2. Dynamic mechanical properties of the fabricated 3wt% or 5 wt% nanocomposites of these aliphatic copolyesters showed significant enhancements in the storage modulus compared with the neat matrix, even higher than that of PBSu. The effect of MMT-K2 on the isothermal crystallization behavior of PBSu, PBPSu90/10, and PBPSu80/20 was investigated using a differential scanning calori- meter (DSC) and polarized light microscopy (PLM). The Avrami equation successfully describes the isothermal crystallization kinetics of these nanocomposites and the value of Avrami exponent was between 2.42 and 3.35. The crystallization rate of neat BP80 was faster than BP80/MMT nanocomposites. This may be ascribed to the incompatibility of BP80 with MMT. On the contrast, the crystallization rate of BP90 or B100 nanocomposites was enhanced as the amount of MMT-K2 increased. The molecular weight of neat polymer before and after the melt intercalation indicated that the reduced molecular weight resulted in the increase of the growth rate of spherulites. Besides, it was found that the incorporation of MMT-K2 has little effect on the crystalline structure as well as the melting behavior of B100, BP90, or BP80.

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33

He, Wei-Syuan, and 何維軒. "Preparation and Properties of Biodegradable Poly(lactic acid)/Jeffamine® polyetheramine Modified Multi-Walled Carbon Nanotube Nanocomposites." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/93824618197117543351.

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碩士
朝陽科技大學
應用化學系碩士班
100
In this study, poly(lactic acid)/multi-walled carbon nanotubes (PLA/MWCNTs) hybrids were prepared by a melt-blending method. In order to enhance the compatibility between PLA and MWCNTs, the surfaces of MWCNTs were chemically modified. MWCNTs were first pre-treated using acid solution (HNO3) to obtain functionalized carboxylic groups. Subsequently, Jeffamine® Polyetheramines (M600 (EO/PO = 1/9), M1000 (EO/PO = 19/3), M2005 (EO/PO = 6/29) and M2070 (EO/PO = 33/10) were grafted onto MWCNTs with the assistance of a dehydrating agent, N，N，-dicyclohexyl-carbodiimide (DCC), respectively. As a result, organically modified MWCNTs (MWCNT-M600, MWCNT-M1000, MWCNT-M2005 and MWCNT-M2070) were obtained. The PLA/MWCNTs nanocomposites were further prepared through the melt-blending method. Thermal behavior, mechanical properties, and conductivity of resultant PLA/MWCNTs composites were investigated. Moreover, the effects of different molecular weight and EO / PO ratio of Jeffamine® Polyetheramines on the properties of modified carbon nanotubes and PLA composites were discussed. The results show that low-molecular-weight Jeffamine® Polyetheramine modified carbon nanotubes (MWCNT-M600 and MWCNT-M1000) can effectively improve the thermal properties of the PLA composites. On the other hand, high-molecular-weight Jeffamine® Polyetheramine modified carbon nanotubes (MWCNT-M2005 and MWCNT-M2070) were uniformly dispersed in the PLA, and can effectively improve the mechanical properties, and conductivity of composite materials. With the addition of 3.0 wt% of MWCNT-M600, Td of the nanocomposite was 7.2℃ higher than that of the pristine PLA sample. With the addition of 3.0 wt% of MWCNT-M2070, the increments of E’ and E” of the nanocomposite at 40℃ was 79.0% and 86.4%. In the aspect of conductivity, the surface resistivity decreased form 1.27×1012 Ω/□ for neat PLA to 8.30×10-3 Ω/□ for the nanocomposites with 3.0 wt% of MWCNT-M2070. Such PLA/MWCNT-M2070 nanocomposites are highly efficient for anti-static purpose, even electrostatic discharge and EMI shielding, which can be applied in electronic materials.

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Lin, Chin-Sheng, and 林錦昇. "Preparation and properties of biodegradable poly(butylene succinate)/Jeffamine® polyetheramine modified multi-walled carbon nanotube nanocomposites." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/88136801543634315794.

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碩士
國立中興大學
化學工程學系所
98
In this study, poly(butylene succinate)/multi-walled carbon nanotubes (PBS/MWNTs) hybrids were prepared by a melt-blending method. In order to enhance the compatibility between PBS and MWNTs, the surfaces of MWNTs were chemically modified. MWNTs were first pre-treated using acid solution (HNO3) to obtain functionalized carboxylic groups. Subsequently, Jeffamine® polyetheramine (M2005 (EO/PO = 6/29) and M2070 (EO/PO = 33/10)) were respectively grafted onto MWNTs with the assistance of a dehydrating agent, N,N’-dicyclohexyl-carbodiimide (DCC). As a result, organically modified MWNTs (MWNT-2005D and MWNT-2070D) were obtained. It was found that MWNT-2005D could be well dispersed in organic solvents such as acetone, THF, and chloroform. In addition, MWNT-2070D could be well dispersed in water. Moreover, the PBS/MWNTs nanocomposites were further prepared through the melt-blending method. Mechanical properties, thermal behavior, and conductivity of resultant PBS/MWNTs composites were investigated. The results show that excellent dispersion of nanotubes in the PBS matrices was achieved. Moreover, an improvement in thermal properties was also observed. With the addition of 3.0 wt % of MWNT-2070D, Td of the nanocomposite was 10.1 oC higher than that of the pristine PBS sample. Apart from that, the increments of E’ and E” of the nanocomposite at 25 oC were 113 and 116 %, respectively. In the aspect of conductivity, the surface resistivity decreased from 2.35×1014 Ω/cm2 for neat PBS to 5.88×103 Ω/cm2 for the nanocomposites with 3.0 wt % of MWNT-2070D. Such PBS/MWNT-2070D nanocomposites are highly efficient for anti-static purpose, even electrostatic discharge and EMI shielding, which can be applied in electronic materials.

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35

AndiAuliawan and 安列望. "Biodegradable ternary blend comprising poly(L-lactic acid), poly(methyl methacrylate), poly(ethylene oxide) as matrix for organoclays nanocomposites." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/93201961438772196790.

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36

Cheng, Shun-Jung, and 鄭舜榮. "Human placenta-derived mesenchymal cells (hPDMCs) seeded in alginate-based nanocomposites combined with biodegradable precision scaffolds for cartilage tissue engineering." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/qxd4xy.

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碩士
長榮大學
生物科技學系(所)
97
Human mesenchymal stem cells are studied extensively such as bone marrow mesenchymal stem cells (BMSCs). However, mesenchymal stem cells from bone marrow could be limited. Human term placenta, a temporary organ is discarded postpartum. In this study, we used human placenta-derived mesenchymal cells (hPDMCs) seeded into PLGA precision scaffolds for chondrogenesis. The mixture, cellulose binding domain Arginine-Glycine- Aspartate (CBD-RGD)/nano-calcium deficient hydroxyapatite (nCDHA) which was absorbed transforming growth factor beta-3(TGF-beta 3)/Alginate, encapsulate hPDMCs to inject a scaffold. The chondrogenic differentiations of the construction are best than others. After 7 days the cell proliferation of the construction were maximum and higher than others, furthermore, it can maintain the maximum cell numbers until 21 days. On the other hand, the component of extracellular matrix (ECM) of the construction was maximum after 7 days, also it can maintain the maximum cell numbers until 21 days. Histological examination revealed the presence of lacuna formation in the ECM. In the same system, the chondrogenic differentiations of hPDMCs are better than hBMSCs. The results of this research suggested hPDMCs can be one of the cell sources for tissue engineering of cartilage.

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37

Pinto, Viviana Maria de Oliveira Correia. "Biodegradable polymer nanocomposites reinforced with carbon nanostructures, PLA/CNT-COOH and PLA/GNP, for augmentation ligament devices: Production and characterization." Tese, 2016. https://hdl.handle.net/10216/96926.

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38

Gao, Guei-De, and 高貴德. "Biodegradable poly(butylene succinate) and its copolyesters with minor amounts of 2-methyl-1,3-propylene succinate/layered double hydroxide nanocomposites." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/83969592261376947217.

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碩士
國立中山大學
材料與光電科學學系研究所
101
In this study, magnesium/aluminum layered double hydroxide (MgAl LDH) with a molar ratio of Mg/Al = 2 was synthesized by the co-precipitation method. In order to improve the compatibility between polymer and LDH, the surface of LDH was organo-modified by sodium dodecyl sulfate (SDS). Poly(butylene succinate) (B100) and its copolyesters with minor amounts of 2-methyl-1,3-propylene succinate (BM90 and BM80) were blended with 1, 3, or 5 wt% of SDS modified LDH, respectively, by the melt intercalation at 120, 100, and 90 °C and at a rotor speed of 50 rpm for 3 min. The physical properties of these biodegradable nanocomposites were characterized before studying their crystallization and melting behaviors. X-ray diffraction patterns and transmission electron micrographs indicated that the LDHs were intercalated and exfoliated, island-type exfoliated, and island-type exfoliated into the B100, BM90, and BM80 matrix, respectively, when the content of LDHs was 3 wt%. TGA results revealed that the thermal stability of the resultant nanocomposites was reduced after the addition of LDH. DSC heating thermograms of the amorphous nanocomposites (at a heating rate of 10 °C/min under nitrogen atmosphere) indicated that the cold crystallization ability and the degree of crystallinity of these nanocomposites decreased as the amount of LDH increased. Dynamic mechanical properties of the fabricated 3 wt% nanocomposites (at a heating rate of 2 °C/min) showed significant enhancements in the storage modulus compared with the neat matrix and 1 or 5 wt% nanocomposites. The effect of LDH-SDS on the isothermal crystallization behavior of B100, BM90, and BM80 was investigated using a differential scanning calorimeter (DSC) and polarized light microscopy (PLM). The Avrami equation successfully describes the isothermal crystallization kinetics of these nanocomposites and the value of Avrami exponent was between 2.32 and 3.15. The rate constant was significantly reduced when the amount of LDH was 3 wt%. Besides, it was found that the incorporation of LDH-SDS has little effect on the crystalline structure as well as the melting behavior of B100, BM90, and BM80. PLM micrographs revealed that smaller and less perfect crystals were formed in the nanocomposites because of the steric hindrance of the matrix diffusion, i.e. reducing the transportation ability of polymer chains during the crystallization. Finally, the overall results suggest that LDH-SDS at nanometer level acted as non-nucleating agent and decelerated the overall crystallization process of B100, BM90, and BM80.

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39

Pinto, Viviana Maria de Oliveira Correia. "Biodegradable polymer nanocomposites reinforced with carbon nanostructures, PLA/CNT-COOH and PLA/GNP, for augmentation ligament devices: Production and characterization." Doctoral thesis, 2016. https://hdl.handle.net/10216/96926.

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40

Wu, Tsan-Biao, and 吳贊標. "Preparation and characterization of biodegradable polymer/natural material nanocomposite." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/63092717159937219389.

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碩士
國立中興大學
材料科學與工程學系所
103
Poly (butylene succinate-co-adipate) (PBSA), a biodegradable linear aliphatic polyester, can be potentially applied as the biomedical and eco-friendly materials. PBSA has good processing properties to be used for general processing machines. The cellulose also belonged to natural materials. In order to well distributed cellulose into PBSA polymer matrix, cellulose acetate butylene (CAB) containing acetyl and butyryl groups, can be acted as a good compatibilizer between PBSA and cellulose. In this study, the preparation of various sizes of cellulose, such as microcrystalline cellulose (MCC), physically grinding cellulose nanocrystals (PNCC), and chemically- modified cellulose nanocrystals (CNCC), was added into PBSA polymer matrix. To understand the crystallization behavior, physical properties, and the degradation of biodegradable composites, the biodegradable composites were analyzed by differential scanning calorimeter (DSC), dynamic mechanical analyzer (DMA), universal testing machine, fourier transform infrared spectrometer (FT-IR), and enzyme degradation. The cellulose nanocrystals were prepared by chemical hydrolysis of microcrystalline cellulose in an ammonium persulfate (APS) solution. The FT-IR spectrum of CNCC contains one more absorption band at 1735cm-1 compared to that of MCC. The result indicated that CNCCs were successfully modified by APS. The biodegradable composites were prepared by melt-mixing the PBSA and reinforcement. The result of non-isothermal crystallization showed that the crystallization temperature of composites were lower than neat PBSA. The storage modulus and Tg were increased as the content of PNCC and CNCC increases. These results indicated that PNCC/CNCC can inhibit mobility of PBSA polymer chains. The tensile modulus of PBSA composites were higher compared to neat PBSA. It postulated CAB was a good compatibilizer for composites. Degradation tests use Lipase from Pseudomonas fluorescens as the enzyme enzymatic degradation solution. It can be observed that the percentage of weight loss for the composites with CAB exhibit a much lower disintegration rate than that of the neat PBSA. The results showed that the sizes of enzymes are too large to penetrate deeply into the PBSA matrix and the CAB can act as the barrier to limit the attack of enzymes.

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41

Chou, Hung-Chia, and 周泓佳. "The Development of Biodegradable Polylactic Acid Nanocomposite Materials Utilized in Engineering Plastic." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/74065517064137861268.

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碩士
國立臺灣大學
化學工程學研究所
100
This study of polymer nanocomposites was focused on the discussion of feasibility that PLA based plastics that can be used on automobile or furniture. This experimental research have been set on the discussion of crystallinity, mechanical and thermal properties of thermoplastic polyurethane (TPU) toughened PLA/ montmorillonite (MMT) nanocomposites, and the goal of this research is to improve their applicability and sustainability to reach the requirements of application on commercial products without much sacrifice in their biodegradability. The tensile test and flexural test showed that PLA blending with TPU in 10 wt %, talc in 4 wt%, and OMC in 2 wt% owes the highest modulus and strength without much sacrifice for elongation while the result form impact test show that the specimen of similar formula without OMC displays the highest impact resistance of 33.07 J/m. The hardness test showed similar tendency with the results of elastic modulus. The heat distortion temperature (HDT) tests showed that the specimens without annealing would not much alter their HDT even adding inorganic fillers while the specimens with thermal treatment would dramatically raise the HDT, which may come from the increase of crystallinity after thermal treatment. The observation under electron microscope demonstrated that the incorporation of inorganic fillers would dramatically alter the heterogeneous morphology of PLA/TPU blending. On the other hand, the incorporation of glass fiber in these nanocomposites showed the significant enhancement of mechanical strength with no interference on their thermal behaviors. In the conclusion, this research provides a possible route to prepare biodegradable engineering plastics in traditional method.

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42

LEE, YA-LUN, and 李亞倫. "Study of biodegradable polymer/clay nanocomposite implanted in gastro intestinal (GI) tract fixation." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/29pc4m.

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碩士
國立臺灣科技大學
應用科技研究所
107
This research aim to control body weight and blood glucose of diabetic obesity rats by implant biodegradable polymer duodenal barrier, which is made by polycaprolactone/poly(D,L-lactic acid) blend clay nanocomposite. Obesity and type II diabetes is the serious medical problems in recent years. Surgery is still the gold-standard treatment for morbid obesity and obesity related type II diabetes, which changes the structure of the digestive tract and gastrointestinal physiology. But surgical risk and complication may cause the physiological and psychological stress of patients. Non-invasive therapy may be an alternative treatment for obesity and diabetes mellitus. Some research have already proved that implants a barrier, covering partial of the duodenum can alter intestinal hormones and reduce body weight and blood glucose. Polycaprolactone and poly(D,L-lactic acid) are two well-known biodegradable polymer, having great biocompatibility and fine mechanical properties. To enhance the mechanical properties of biodegradable polymer, polycaprolactone and poly(D,L-lactic acid) blend with nano-clay Laponite® under different content ratio. PCL/PDLLA/Laponite® nanocomposite has largest improvement of 109% in tensile test. Four weeks after duodenal barrier implant in intestine of diabetic obesity rats, body weight and blood glucose both have obvious improvement. Histopathological section report showed no acute symptoms of inflammation.

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43

Kim, Yongha. "Polymer nanocomposite foams : fabrication, characterization, and modeling." Thesis, 2012. http://hdl.handle.net/2152/ETD-UT-2012-12-6849.

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Polymer nanocomposite foams have attracted tremendous interests due to their multifunctional properties in addition to the inherited lightweight benefit of being foamed materials. Polymer nanocomposite foams using high performance polymer and bio-degradable polymer with carbon nanotubes were fabricated, and the effects of foam density and pore size on properties were characterized. Electrical conductivity modeling of polymer nanocomposite foams was conducted to investigate the effects of density and pore size. High performance polymer Polyetherimide (PEI) and multi-walled carbon nanotube (MWCNT) nanocomposites and their foams were fabricated using solvent-casting and solid-state foaming under different foaming conditions. Addition of MWCNTs has little effect on the storage modulus of the nanocomposites. High glass transition temperature of PEI matrix was maintained in the PEI/MWCNT nanocomposites and foams. Volume electrical conductivities of the nanocomposite foams beyond the percolation threshold were within the range of electro-dissipative materials according to the ANSI/ESD standard, which indicates that these lightweight materials could be suitable for electro-static dissipation applications with high temperature requirements. Biodegradable Polylactic acid (PLA) and MWCNT nanocomposites and their foams were fabricated using melt-blending and solid-state foaming under different foaming conditions. Addition of MWCNTs increased the storage modulus of PLA/MWCNT composites. By foaming, the glass transition temperature increased. Volume electrical conductivities of foams with MWCNT contents beyond the percolation threshold were again within the range of electro-dissipative materials according to the ANSI/ESD standard. The foams with a saturation pressure of 2 MPa and foaming temperature of 100 °C showed a weight reduction of 90% without the sacrifice of electrical conductivity. This result is promising in terms of multi-functionality and material saving. At a given CNT loading expressed as volume percent, the electrical conductivity increased significantly as porosity increased. A Monte-Carlo simulation model was developed to understand and predict the electrical conductivity of polymer/MWCNT nanocomposite foams. Two different foam morphologies were considered, designated as Case 1: volume expansion without nanotube rearrangement, and Case 2: nanotube aggregation in cell walls. Simulation results from unfoamed nanocomposites and the Case 1 model were validated with experimental data. The results were in good agreement with those from PEI/MWCNT nanocomposites and their foams, which had a similar microstructure as modeled in Case 1. Porosity effects on electrical conductivity were investigated for both Case 1 and Case 2 models. There was no porosity effect on electrical conductivity at a given volume percent CNT loading for Case 1. However, for Case 2 the electrical conductivity increased as porosity increased. Pore size effect was investigated using the Case 2 model. As pore size increased, the electrical conductivity also increased. Electrical conductivity prediction of foamed polymer nanocomposites using FEM was performed. The results obtained from FEM were compared with those from the Monte-Carlo simulation method. Feasibility of using FEM to predict the electrical conductivity of foamed polymer nanocomposites was discussed. FEM was able to predict the electrical conductivity of polymer nanocomposite foams represented by the Case 2 model with various porosities. However, it could not capture the pore size effect in the electrical conductivity prediction. The FEM simulation can be utilized to predict the electrical conductivity of Case 2 foams when the percolation threshold is determined by Monte-Carlo simulation to save the computational time. This has only been verified when the pore size is small in the range of a few micrometers.
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44

(8085995), Tahrima Binte Rouf. "Design and Mechanistic Understanding of Zein Nanocomposite Films and Their Implementation in an Amperometric Biosensor for Detection of Gliadin." Thesis, 2019.

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Abstract:

Zein is a major storage protein of corn, with unique amphiphilic film forming properties. It is insoluble in water, but soluble in 70% ethanol and acetic acid, and has been declared ‘generally recognized as safe’ (GRAS) by the FDA. Due to new advances in food nanotechnology, zein is being investigated for various applications such as biodegradable packaging, oral delivery of proteins and peptides, scaffold for tissue engineering, as well as biodegradable sensor platforms. The time consuming and highly complicated methods for toxin and allergen analysis in the food industry necessitates the need for a rapid, selective, compact and easy-to-use method of detection for analytes. In the scope of this dissertation, we investigated the feasibility of functional zein nanocomposite films and formation of a zein nanocomposite sensor assembly for rapid and highly selective electrochemical measurements of food toxins and allergens. Fabrication of a zein based electrochemical amperometric sensor assembly was studied, first through the comparison of various zein film characteristics changes with the application of Laponite®, graphene oxide and carbon nanotube nanoparticles, followed by a proof-of-concept study by detecting the gluten allergen protein gliadin.

To mechanistically study the functional zein nanocomposite films, Laponite®, a silica nanoparticle, was added in the presence of 70% ethanol solvent and oleic acid plasticizer. The films were studied using various characterization techniques like transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), water contact angle measurements etc. Through Si-N bond formation between Laponite® and zein, fabricated zein nanocomposite films showed increase in surface hydrophobicity, water vapor barrier properties, tensile strength and Young’s modulus. Graphene oxide (GO), a carbon nanoparticle, was also incorporated into zein through the solvent casting process. Uniform dispersion of GO nanoparticles within zein matrix were confirmed up to 1% GO loading, and covalent and hydrogen bonding mechanisms were proposed. Similar to zein-Laponite® (Z-LAP) nanocomposites, zein-GO (Z-GO) showed increase in hydrophobic tendencies, rougher surface and a 300% improvement in Young’s modulus and 180% improvement in tensile strength at only 3% GO loading. Both nanoparticles increased tensile strength, thermal stability and water vapor barrier property of the films, indicating a potential for food packaging as an alternative application for the nanocomposite films.

Finally, the research focused on the fabrication of an electrochemical amperometric sensor, capable of detecting the protein gliadin, which is responsible for the allergic reaction with people having celiac disease. Novel biodegradable coatings made from zein nanocomposites: zein-graphene oxide, zein-Laponite® and zein-multiwalled carbon nanotubes (Z-CNT) using drop casting technique were tested for fabricating the electrochemical sensors using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and square wave voltammetry (SWV) techniques. As Z-CNT produced the strongest signals compared to other nanomaterials, the active tip of the electrochemical sensor was functionalized through a sequence of layer by layer deposition of Z-CNT nanocomposite, antibody and target analyte. Here, Z-CNT acts as a natural linker molecule with large number of functional groups, that causes immobilization of capture antibody and target, to ensure high sensor performance. Both CV curves and SWV curves indicated successful sequential immobilization of gliadin antibody onto the Z-CNT coated electrode. The Z-CNT biosensor was successfully able to give CV signals for gliadin toxins for as low as 0.5 ppm and was highly specific for gliadin in the presence of other interfering molecules, and remained stable over a 30-day period. The low-cost, thin, conductive zein films offered a promising alternative for protein immobilization platforms used in sensors and can be extended to other matrices in biosensors as well as other functional film applications

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Dissertations / Theses on the topic 'Biodegradable nanocomposites'

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