Dissertations / Theses on the topic 'Polymer materials'
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Kuruwita-Mudiyanselage, Thilini D. "Smart Polymer Materials." Bowling Green State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1223652552.
Full textMohagheghian, Iman. "Impact response of polymers and polymer nanocomposites." Thesis, University of Cambridge, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648854.
Full textJohnson, Joseph Casey. "Peptidic Materials: Nature Inspired Mechanical Enhancement." Case Western Reserve University School of Graduate Studies / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=case1403197488.
Full textPetsagkourakis, Ioannis. "High performance polymer and polymer/inorganic thermoelectric materials." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0351/document.
Full textConducting polymers (CPs) have recently gained the attention of the scientific community due to their prospective use in thermoelectric applications [1,2]. Particularly, it has been proven that an important parameter for tuning the thermoelectric properties and the charge transport behavior of the CP is the shape of the DOS in the band edge, where a more steep band edge would be translated in a semi-metallic behavior for the system, with higher thermoelectric efficiencies. In the present study the correlation between material structure, electronic structure and electronic/ thermoelectric properties, is investigated through careful material design, towards an efficient thermoelectric polymer material. Additionally, the hybrid devices were fabricated as an alternative means to further enhance the thermoelectric efficiency of the material
Lin, Yinan. "Electrospinning Polymer Fibers for Design and Fabrication of New Materials." University of Akron / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=akron1310997689.
Full textKumpfer, Justin Richard. "Utilizing Metallosupramolecular Polymers as Smart Materials." Case Western Reserve University School of Graduate Studies / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=case1333553702.
Full textSakahara, Rogério Massanori. "Estudo da formação da fase cristalina beta nos compósitos de polipropileno contendo anidrido maléico e carbono de cálcio." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/3/3133/tde-04072013-153850/.
Full textThis study aimed at improving the comprehension of the influence of calcium carbonate (CaCO3) in the formation of the beta crystalline phase of polypropylene (PP), as well as the changes in the mechanical properties of this polymer. A preliminary analysis of the grafting of the maleic anhydride in the polypropylene was carried out in order to produce specimens for the study, owing to the fact that this grafted polypropylene (PP-g-MA) contributes substantially to change the polarity of the polymer and therefore, enhance the superficial adhesion between PP and CaCO3. Two grafting methods using organic peroxide were studied. The grafted copolymers were analyzed by DSC, TGA, SEM, EDS, and FTIR. Two series of PP composites containing CaCO3 were produced by intensive melt mixing (Drais mixer), one of them having MA-g-PP. Four types of CaCO3 were used, which diameters were 0.9 µm, 2.5 µm and 3 µm, though the CaCO3 0.9 µm was surface-treated and non-treated. The concentration of CaCO3 was maintained at 5% and PP-g-MA at 5 % also, when present. The composites were tested for tensile strength, flexural modulus and impact strength (at two temperatures). Samples containing smaller particle sized CaCO3 and PP-g-MA showed synergistic improvement in the mechanical strength, and increases in the impact resistance and flexural strength were observed. Analysis of the beta crystal phase in these samples was performed using DSC and x-ray diffractometry. The influence of superficial adhesion between CaCO3 and PP was also analyzed, higher concentration of the beta crystalline phase was observed for better surface adhesion and smaller CaCO3 particle size, which contributed to the synergy between all the mechanical properties evaluated in this work.
Liu, Liu. "Durability of Polymer Composite Materials." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/14002.
Full textVukicevic, Uros. "TiO2 nanorod polymer composite materials." Thesis, Imperial College London, 2009. http://hdl.handle.net/10044/1/7669.
Full textFuller, Kristin M. "Bridging the Gap: Developing Synthetic Materials with Enzymatic Levels of Complexity and Function." Case Western Reserve University School of Graduate Studies / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=case1595941048642725.
Full textMonemian, Seyedali. "Tuning Mechanics of Bio-Inspired Polymeric Materials through Supramolecular Chemistry." Case Western Reserve University School of Graduate Studies / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=case1467882025.
Full textFan, Weizheng. "Development of Photoresponsive Polymers and Polymer/Inorganic Composite Materials Based on the Coumarin Chromophore." University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1366903513.
Full textLee, Jung-Hyun. "Interface engineering in zeolite-polymer and metal-polymer hybrid materials." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/37120.
Full textLiu, Ruofan. "A Novel Methodology for Durability Assessment of Rubber Materials." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1525784654741047.
Full textChirowodza, Helen. "Polymer-clay nanocomposites prepared by RAFT-supported grafting." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/71914.
Full textENGLISH ABSTRACT: In materials chemistry, surface-initiated reversible deactivation radical polymerisation (SI-RDRP) has emerged as one of the most versatile routes to synthesising inorganic/organic hybrid materials consisting of well-defined polymers. The resultant materials often exhibit a remarkable improvement in bulk material properties even after the addition of very small amounts of inorganic modifiers like clay. A novel cationic reversible addition–fragmentation chain transfer (RAFT) agent with the dual purpose of modifying the surface of Laponite clay and controlling the polymerisation of monomer therefrom, was designed and synthesised. Its efficiency to control the polymerisation of styrene was evaluated and confirmed through investigating the molar mass evolution and chain-end functionality. The surface of Laponite clay was modified with the cationic chain transfer agent (CTA) via ion exchange and polymerisation performed in the presence of a free non-functionalised CTA. The addition of the non-functionalised CTA gave an evenly distributed CTA concentration and allowed the simultaneous growth of surface-attached and free polystyrene (PS). Further analysis of the free and grafted PS using analytical techniques developed and published during the course of this study, indicated that the free and grafted PS chains were undergoing different polymerisation mechanisms. For the second monomer system investigated n-butyl acrylate, it was apparent that the molar mass targeted and the monomer conversions attained had a significant influence on the simultaneous growth of the free and grafted polymer chains. Additional analysis of the grafted polymer chains indicated that secondary reactions dominated in the polymerisation of the surface-attached polymer chains. A new approach to separating the inorganic/organic hybrid materials into their various components using asymmetrical flow field-flow fractionation (AF4) was described. The results obtained not only gave an indication of the success of the in situ polymerisation reaction, but also provided information on the morphology of the material. Thermogravimetric analysis (TGA) was carried out on the polymer-clay nanocomposite samples. The results showed that by adding as little as 3 wt-% of clay to the polymer matrix, there was a remarkable improvement in the thermal stability.
AFRIKAANSE OPSOMMING: Oppervlakgeïnisieerde omkeerbare deaktiveringsradikaalpolimerisasie (SI-RDRP) is een van die veelsydigste roetes om anorganiese/organiese hibriedmateriale (wat bestaan uit goed-gedefinieerde polimere) te sintetiseer. Die produk toon dikwels ʼn merkwaardige verbetering in die makroskopiese eienskappe – selfs na die toevoeging van klein hoeveelhede anorganiese modifiseerders soos klei. ʼn Nuwe kationiese omkeerbare addisie-fragmentasie kettingoordrag (RAFT) middel met die tweeledige doel om die modifisering van die oppervlak van Laponite klei en die beheer van die polimerisasie van die monomeer daarvan, is ontwerp en gesintetiseer. Die klei se doeltreffendheid om die polimerisasie van stireen te beheer is geëvalueer en bevestig deur die molêre massa en die funksionele groepe aan die einde van die ketting te ondersoek. Die oppervlak van Laponite klei is gemodifiseer met die kationiese kettingoordragmiddel (CTA) deur middel van ioonuitruiling en polimerisasie wat uitgevoer word in die teenwoordigheid van ʼn vrye nie-gefunksionaliseerde CTA. Die toevoeging van die nie-gefunksionaliseerde CTA het ʼn eweredig-verspreide konsentrasie CTA teweeggebring en die gelyktydige groei van oppervlak-gebonde en vry polistireen (PS) toegelaat. Verdere ontleding van die vrye- en geënte PS met behulp van analitiese tegnieke wat ontwikkel en gepubliseer is gedurende die verloop van hierdie studie, het aangedui dat die vry- en geënte PS-kettings verskillende polimerisasiemeganismes ondergaan. n-Butielakrilaat is in die tweede monomeer-stelsel ondersoek en dit was duidelik dat die molêre massa wat geteiken is en die geënte polimeerkettings. ʼn Nuwe benadering tot die skeiding van die anorganiese/organiese hibriedmateriale in hulle onderskeie komponente met behulp van asimmetriese vloeiveld-vloei fraksionering (AF4) is beskryf. Die resultate wat verkry is, het nie net 'n aanduiding gegee van die sukses van die in-situ polimerisasiereaksie nie, maar het ook inligting verskaf oor die morfologie van die materiaal. Termogravimetriese analise (TGA) is uitgevoer op die polimeer-klei nanosaamgestelde monsters. Die resultate het getoon dat daar 'n merkwaardige verbetering in die termiese stabiliteit was na die toevoeging van so min as 3 wt% klei by die polimeermatriks.
Chang, Kaiguo. "Synthesis and characterization of conducting polymer-inorganic composite materials /." View online ; access limited to URI, 2000. http://0-wwwlib.umi.com.helin.uri.edu/dissertations/dlnow/3108646.
Full textRazgoniaev, Anton. "Design, synthesis, and characterization of photoresponsive materials usingcoordination bonds and other supramolecular interactions." Bowling Green State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1510918007338796.
Full textLiu, Yi. "Mesoporous silica/polymer nanocomposites." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31739.
Full textCommittee Chair: Jacob. Karl; Committee Member: Griffin. Anselm; Committee Member: Tannenbaum. Rina; Committee Member: Thio. Yonathan S; Committee Member: Yao. Donggang. Part of the SMARTech Electronic Thesis and Dissertation Collection.
Mahaffy, Rachel Elaine. "The quantitative characterization of the viscoelastic properties of cells and polymer gels /." Full text (PDF) from UMI/Dissertation Abstracts International, 2000. http://wwwlib.umi.com/cr/utexas/fullcit?p3004328.
Full textHarton, Shane Edward. "Investigation of Polymer Phase Behavior at Heterogeneous Polymer-Polymer Interfaces using Secondary Ion Mass Spectrometry." NCSU, 2006. http://www.lib.ncsu.edu/theses/available/etd-03012006-131419/.
Full textSasanaluckit, Piyamol Nuttanun. "Bone biocompatibilty of polymer based materials." Thesis, University of Liverpool, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386914.
Full textBen, Sghaier Asma. "Hybrides polymer materials organic/inorganic nanoparticule." Thesis, Paris Est, 2018. http://www.theses.fr/2018PESC1163.
Full textDiazonium interface chemistry has progressed over the last few years and practically involved in all areas of materials science and engineering. The rationale for employing diazonium salts is that they attach to surfaces with remarkable bond energies, particularly on sp² carbon materials, making them an ideal coupling agent for polymers to surfaces In this context, novel CNT-polytriazole (CNT-PTAz) and CNT-dye nanohybrids were designed and thoroughly characterized. First, CNT-PTAz nanohybrid was prepared by click polymerization: multiwalled carbon nanotubes (CNTs) were modified with azidophenyl groups (CNT-N3) from 4-azidobenzenediazonium precursor and served as nanoscale platform for the surface confined polyaddition. The CNT-PTAz nanohybrid was characterized by TGA, XPS, IR, and Raman. The robust CNT-PTAz is robust and has potential in developing heavy metal adsorbents, nanosupport for catalysts or for gas storage. In the second major part, we grafted CNT with diazotized Neutral red (NR), Azure A (AA) and Congo Red (CR) dyes by simple, spontaneous reaction of the diazonium salts and CNTs in water, at RT. A thorough investigation of the nanohybrids showed that the adhesion is strong (CNT-dye C-C bond energy higher than 150 kJ/mol), and the layer is uniform. These nanohybrids further served to reinforce ethylene-vinyl acetate (EVA) an elastomeric matrix. The reinforced matrix is flexible and serves as optothermal actuators where the grafted dye catches the light to induce mechanical changes in the matrix monitored by dynamic mechanical analysis. CNT/dye-reinforced EVA is a promising flexible composite for developing new types of visual-aid tablet for visually impaired people. The versatile CNT-dye nanohybrids are also unique chemiresistive gas sensors for the molecular recognition of acetone vapours. In a final application, CNT-CR nanohybrid was investigated as an electrocatalyst for the Direct Oxidation of Methanol. Interesting results were obtained with these nanohybrids but significant improvements (3-fold) of the electrocatalytic properties were achieved with CNT-CR decorated with gold nanoparticles. The newly designed electrocatalytic system could be regarded for different promising applications most likely as for sensors, biosensors, heterogeneous catalysts for fuel cells and for nanotechnology To summarize, newly designed CNT-based nanohybrids have unique performances ascribed to the versatility of the diazonium interface chemistry in efficiently attaching functional molecular and macromolecular layers. The novel nanohybrids serve as building blocks for designing high performance nanocomposite materials relevant to challenging timely social economic issues, namely environment, biomedicine and energy
Hall, David Steven. "Metal polymer adhesion for packaging materials." Thesis, Oxford Brookes University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245702.
Full textMa, Xiaolu. "Bis (trialkoxysilyl) telechelic polymer materials for adhesive applications." Thesis, Rennes 1, 2016. http://www.theses.fr/2016REN1S123.
Full textThe work presented focuses on the synthesis of liquid (at room temperature) bis(trialkoxysilyl) telechelic polyolefins for adhesive applications. The first approach relies on the combined ring-opening metathesis polymerization/cross metathesis (ROMP/CM) of a cycloolefin or a mixture of cycloolefins using a trialkoxysilyl mono- or difunctionalized alkene acting as a chain transfer agent (CTA) and a ruthenium-based catalyst. The efficiency of the reaction and selectivity of the polymer functionality were found to depend much on the nature of the CTA, the catalyst, the solvent and the use of benzoquinone additive as isomerization inhibitor. A high catalytic productivity with a turnover number (TON) up to 100 000 was obtained under optimized conditions. The viscosity of polymers was controlled by adjusting the nature and the ratio of comonomers. The second approach is dedicated to the depolymerization of liquid high 1,4-cis polybutadiene (PBD) in the presence of a CTA and a ruthenium catalyst. The catalytic productivity and selectivity were optimized by changing the method of purification of the commercial PBD, the nature of catalyst and the reaction protocol. This second approach remains, however, less efficient than the first one
Moran, Stephanie E. (Stephanie Elizabeth). "Polymer coated superparamagnetic beads walking on polymer coated surface." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/76123.
Full textCataloged from PDF version of thesis.
Includes bibliographical references (p. 30-31).
Biology has provided us with many organisms that are able to propel themselves through a fluid using cilia or flagella. This provides inspiration to create controllable systems that cannot only propel an organism or device through a fluid but can also create a fluid flow. Research has focused on how to mimic the mechanisms of these organisms for the use in microfluidic devices or drug delivery. This work examines walkers that are created using superparamagnetic beads placed in a rotating external magnetic field. Dipoles align in the beads so they assemble into rotors. These rotors follow the rotating magnetic field and are able to translate across a surface. This work looks at the effect of coating the beads and the surface with a polymer, Polyethylene Glycol(PEG). PEG has been shown to undergo a transition from an expanded state to a collapsed state under certain salt concentrations and temperature ranges. By looking at this transition we can see if the use of a polymer could affect the velocity of the rotors and if PEG could be used to control the velocity of the rotors or to initiate a transition. This transition is only seen by recording the velocity of the rotors, future research using other experimental procedures might be helpful in finalizing the transition of PEG in NaCl. It was unclear from these experiments whether the velocity of the rotors is dependent on the state of the polymer.
by Stephanie E. Moran.
S.B.
Ju, Lin. "Non-Covalent Interactions in Polymeric Materials: From Ionomers to Polymer Blends." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/102651.
Full textDoctor of Philosophy
Chen, Biqiong. "Polymer-clay nanocomposites." Thesis, Queen Mary, University of London, 2004. http://qmro.qmul.ac.uk/xmlui/handle/123456789/1854.
Full textCreusen, Guido [Verfasser], and Andreas [Akademischer Betreuer] Walther. "Bottom-up materials design with defined polymer and polymer-DNA structures." Freiburg : Universität, 2021. http://d-nb.info/124147222X/34.
Full textMazzoccoli, Jason Paul. "ULTRASONICATION OF POLYSACCHARIDE MATERIALS." Cleveland, Ohio : Case Western Reserve University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=case1262572128.
Full textDepartment of Chemical Engineering Title from PDF (viewed on 2010-05-25) Includes abstract Includes bibliographical references and appendices Available online via the OhioLINK ETD Center
Barris, Peña Cristina. "Serviceability behaviour of fibre reinforced polymer reinforced concrete beams." Doctoral thesis, Universitat de Girona, 2011. http://hdl.handle.net/10803/7772.
Full textSe presentan los aspectos principales que influyen en los estados límites de servicio: tensiones de los materiales, ancho máximo de fisura y flecha máxima permitida. Se presenta una metodología para el diseño de dichos elementos bajo las condiciones de servicio. El procedimiento presentado permite optimizar las dimensiones de la sección respecto a metodologías más generales.
Fibre reinforced polymer (FRP) bars have emerged as an alternative to steel for reinforced concrete (RC) elements in aggressive environments due to their non-corrosive properties. This study investigates the short-term serviceability behaviour of FRP RC beams through theoretical and experimental analysis. Twenty-six RC beams reinforced with glass-FRP (GFRP) and one steel RC beam are tested under four-point loading. The experimental results are discussed and compared to some of the most representative prediction models of deflections and cracking for steel and FRP RC finding that prediction models generally provide adequate values up to the service load. Additionally, cracked section analysis (CSA) is used to analyse the flexural behaviour of the specimens until failure. CSA estimates the ultimate load with accuracy, but it underestimates the experimental deflection beyond the service load level. This increment is mainly attributed in this work to shear induced deflection and it is experimentally calculated.
A discussion on the main aspects of the SLS of FRP RC is introduced: the stresses in materials, maximum crack width and the allowable deflection. A methodology for the design of FRP RC at the serviceability requirements is presented, which allows optimizing the overall depth of the element with respect to more generalised methodologies.
Bo, Ni. "Design, Synthesis and Self-assembly of Polyhedral Oligomeric Silsesquioxane (POSS) Based Hybrid Materials." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron152130982499385.
Full textTangvijitsakul, Pattarasai. "Methoxy Poly (Ethylene Glycol) Methacrylate- Based Copolymers on the Applications of Concrete Admixtures, Mesoporous Materials, and Rheology Modifiers." University of Akron / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1442440564.
Full textLi, Weiyao. "Understanding UV Protection Mechanism of Natural and Synthetic Eumelanin." University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1491930546268438.
Full textZhou, Wenxuan. "Stoichiometry and Crystal Structure of Poly (Lactic Acid) (PLA) Stereocomplex (SC) in Cold-crystallization and Solution-grown Crystals as Studied by Solid-state NMR and 13C Isotope Labeling." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1522239647112751.
Full textShokouhi, Mehr Hamideh. "Application of High-Performance Polyimides in Additive Manufacturing and Powder Coating." University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron1574204777058183.
Full textRen, Xianjie ren. "Improving sustainability of rubber composites with renewable additives and epoxidized guayule natural rubber." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1574440536318129.
Full textMawhinney, Kaitlyn Elizabeth. "Design and Characterization of Emulsion-Templated Macroporous-Mesoporous Polyurea Gels and Aerogels." University of Akron / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=akron1597401264429047.
Full textWang, Menghong. "Degradation of Photovoltaic Packaging Materials and Power Output of Photovoltaic Systems: Scaling up Materials Science with Data Science." Case Western Reserve University School of Graduate Studies / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=case1595416965256375.
Full textMarcus, Kashif. "Micromechanisms of polymer sliding wear." Doctoral thesis, University of Cape Town, 1993. http://hdl.handle.net/11427/22408.
Full textDahlen, Anfrid. "Plastic deformation and fracture of polymer materials." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for konstruksjonsteknikk, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-15968.
Full textBoudara, Victor Ange Henri. "Supramolecular and entangled polymer materials : rheological models." Thesis, University of Leeds, 2017. http://etheses.whiterose.ac.uk/19802/.
Full textWang, Peng-zhu. "Investigation of scratch damage on polymer materials." Thesis, University of Cambridge, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620732.
Full textKashfipour, Marjan Alsadat. "Thermal Conductivity Enhancement Of Polymer Based Materials." University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron156415885613422.
Full textLorenzana, Chad. "Fiber reinforced polymer strengthening in construction materials." Thesis, Washington University of Washington, 2006. http://hdl.handle.net/10945/2329.
Full textThe United States has experienced an increase in the need for structural repair, especially in its public transportation infrastructure. At the same time, societal requirements to keep these structures open have placed pressure on facility engineers to perform rapid retrofits which entail minimal disruption to these systems. This need has brought the use of Fiber Reinforced Polymers (FRP) to the forefront, as its properties have proven to be invaluable in other industries such as boating, aircraft, and recreation. Its high strength-to-weight ratio, non-corrosive nature, relatively simple application techniques, and non-invasive application procedures have moved FRPs to the top of the list compared to its strengthening contemporaries, mainly steel, in terms of structural retrofits.
Contract number: N62271-97-G-0075.
CIVINS
Gurun, Bilge. "Deformation studies of polymers and polymer/clay nanocomposites." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/37118.
Full textHarish, Muthuraman. "Processing and Study of Carbon Nanotube / Polymer Nanocomposites and Polymer Electrolyte Materials." Master's thesis, University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4247.
Full textM.S.M.S.E.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Materials Science & Engr MSMSE
Lin, Jian. "Novel Lithium Salt and Polymer Electrolytes for Polymer Lithium Batteries." Case Western Reserve University School of Graduate Studies / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=case1215572988.
Full textMalan, Mareta. "Novel materials for VOC analysis." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/71646.
Full textENGLISH ABSTRACT: The need to analyse and detect volatile organic compounds (VOCs) at trace levels has led to the development of specialized sample preparation techniques. The requirement for trace analysis of VOCs stems from the negative effects they have on the environmental and human health. Methods for the analysis of non-polar VOCs commonly found as trace contaminants in water and analysis of more polar oxygenated compounds commonly found in zero-VOC water-based paints were developed. Solid phase micro extraction (SPME) was employed and extraction of the majority of the target analytes could be achieved at levels below 0.3 μg.l-1. In an attempt to further improve the detection of these two target analyte groups, novel materials based on poly(dimethyl siloxane) (PDMS) were investigated as possible extraction phases for VOCs, with the focus specifically on the analysis of the polar analytes in paint. Conventional free radical polymerization was used to synthesize poly(methyl methacrylate-graft-poly(dimethyl siloxane) (PMMA-g-PDMS), poly(methacrylic acid)-graft-poly(dimethyl siloxane) (PMAA-g-PDMS), polystyrene-graftpoly( dimethyl siloxane) (PSty-g-PDMS) and poly(butyl acrylate)-graft–poly(dimethyl siloxane) (PBA-g-PDMS). These polymers have a copolymer functionality which presents a series of different polarities. The MMA-g-PDMS and MAA-g-PDMS as well as the homopolymers were electrospun into nanofibers. The low glass transition temperature and molecular weight of the PBAg- PDMS meant that this polymer could not be electrospun. Scanning electron microscopy (SEM) was used to study the fiber morphology of the electrospun fibers and the non-beaded fibers were further investigated. Polyacrylonitrile-graft-poly(dimethyl siloxane) (PAN-g-PDMS) previously synthesized and electrospun by another member of the group were also investigated for use as possible extraction material in volatile analysis. The thermal stability of the nanofibers at 200°C was studied using thermal gravimetric analysis (TGA). This property is important since after the target analytes are extracted using the nanofibers, elevated temperatures are used to thermally desorp the volatile analytes from the extraction materials prior to GC analysis. The PAN-g-PDMS, MMA-g-PDMS and PMMA showed no significant weight loss during thermal evaluation, however, it was observed that the PMMA and PMMA-g-PDMS nanofibers looses their nanostructure and that the PAN-g-PDMS nanofibers changes colour from white to yellow to rust brown. The polymers based on MAA showed weight losses of more than 10% after one hour of exposure to the elevated temperatures, but the nanostructure remained intact. The PAN-g-PDMS, PMAA-g-PDMS and PMAA nanofibers were evaluated as possible extraction materials for VOC analysis. The nanofibers were evaluated using a similar approach to that of stir bar sorptive extraction (SBSE). Headspace sorptive extraction (HSSE) using a commercially available PDMS stir bar and the novel materials were used to evaluate the extraction efficiency of the different materials. The optimized extraction method developed using SPME were employed for the extraction using the nanofibers and PDMS stir bar. It was noted that the nanofibers lose their extraction capabilities during the first extraction/desorption cycle possibly due to thermal degradation therefore each of the materials can only be used in a single extraction. The majority of the non-polar analytes were extracted using the nanofibers at levels of 500 μg.l-1, however it was noted that the commercially available SPME extraction materials and the PDMS stir bar had superior extraction efficiencies for the specific target analytes. In the evaluation of the nanofibers for extraction of the more polar oxygenated analytes it was noted that 2-Ethylhexylacrylate was the only analyte to be extracted by all of the materials. The PAN-g-PDMS extracted three of the four analytes at levels of 100 μg.l-1. At lower analyte concentrations of 10 μg.l-1 only two of the four acrylate compounds were detected using the PAN-g-PDMS nanofibers. Ethyl acrylate was not extracted by any of the novel materials, whereas in SPME using the CAR/PDMS fiber, the LOD was determined to be below 1 μg.l-1. Although these materials were not superior to the commercially available phases, this is only the case for the specific target analytes analyzed.
AFRIKAANSE OPSOMMING: Die behoefte vir die analiese van vlugtige organiese verbindings (VOS) op spoorvlak, het gelei tot die ontwikkeling van gespesialiseerde monster voorbereidingstegnieke. Die vereiste vir die spoor analiese van die VOS het ontstaan uit die negatiewe uitwerking wat hierdie stowwe het op die omgewing en menslike gesondheid. Metodes vir die analiese van nie-polêre VOS wat algemeen voorkom as spoorkontaminante in water en polêre suurstofryke verbindings wat algemeen voorkom in nul-VOS water-gebaseerde verf was ontwikkel. Soliede fase mikro-ekstraksie (SFME) was gebruik, en die ekstraksie van die meerderheid van die teikenstowwe kon gedoen word op vlakke laer as 0,3 μg.l-1. In 'n poging om die opsporing van hierdie twee teiken analietgroepe verder te verbeter, is nuwe materiale gebaseer op polidimetielsiloksaan (PDMS), ondersoek as moontlik ekstraksiefases vir VOS, met die fokus spesifiek op die analiese van die polêre stowwe in verf. ’n Konvensionele vrye radikaal polimerisasieproses was gebruik om poli (metiel- metakrilaat)-entpoli( dimetielsiloksaan) (PMMA-g-PDMS), poli(metakrilaatsuur)-ent–poli (dimetielsiloksaan) (PMAA-g-PDMS), polistireen-ent-poli(dimetielsiloksaan) (PSty-g-PDMS) en poli(butielakrilaat)- ent-poli(dimetielsiloksaan) (PBA-g-PDMS) te sintetiseer. Hierdie ko-polimere het 'n kopolimeer funksionaliteit wat 'n reeks van verskillende polariteite bied. Die MMA-g-PDMS en MAA-g-PDMS sowel as die homopolimere was ge-elektrospin in orde om nanovesels te vorm. Die lae glasoorgangstemperatuur en molekulêre gewig van die PBA-g-PDMS het beteken dat hierdie polimeer nie elektrospin kon word nie. Skandeerelektronmikroskopie (SEM) was gebruik om die veselmorfologie van die ge-elektrospinde vesels te bestudeer en die nanovesels wat ’n eweredige oppervlak gehad het, was verder ondersoek. Poliakrilonitriel-ent-poli(dimetielsiloksaan) (PAN-g- PDMS) wat voorheen gesintetiseer en ge-elektrospin was deur 'n ander lid van die groep is ook ondersoek vir gebruik as moontlik ekstraksiemateriaal vir die analiese van vlugtige stowwe. Die termiese stabiliteit van die nanovesels was by 200°C bestudeer met behulp van ‘n termiese gravimetriese analiese (TGA) instrument. Hierdie eienskap is belangrik, aangesien die teikenstowwe by hoë temperature van die nanovesels gedesorbeer word voor die GC-analiese. Die PAN-g-PDMS, MMA-g-PDMS en PMMA het geen beduidende gewigsverlies tydens termiese evaluering gehad nie, alhoewel dit egter waargeneem was dat die PMMA en PMMA-g-PDMS nanovesels hulle nanostruktuur verloor en dat die PAN-g-PDMS nanovesels se kleur verander van wit na geel na roesbruin gedurende die termiese analiese. Die polimere wat gebaseer was op MAA het ’n gewigs-verlies van meer as 10% getoon na 'n uur van blootstelling aan die verhoogde temperature, maar die nanostruktuur het ongeskonde gebly. Die PAN-g-PDMS, PMAA-g-PDMS en PMAA nanovesels was geëvalueer as moontlike ekstraksiemateriale vir VOS-analiese. Die nanovesels was geëvalueer met 'n soortgelyke benadering tot dié van “stir bar“ sorpsie ekstraksie (SBSE). Bo-ruimte sorpsie ekstrasie is gebruik om die ekstraksie-doeltreffendheid van die verskillende materiale (kommersiële PDMS en nanovesels) te evalueer. Die geoptimaliseerde ekstraksiemetode ontwikkel in SFME was gebruik vir die ekstraksie van die VOS met die nanovesels en die PDMS “stir bar“. Dit was waargeneem dat die nanovesels hul ekstraksievermoë verloor tydens die eerste ekstraksie/desorpsie siklus, moontlik as gevolg van termiese degradasie dus, kon die materiale slegs ‘n enkele maal gebruik word vir die ekstraksie. Die meerderheid van die nie-polêre stowwe was ge-ëkstraeer deur gebruik te maak van die nanovesels op vlakke van 500 μg.l -1, maar die kommersieel beskikbare SFME ekstraksie materiale en die PDMS “stir bar“ se ekstraksie-doeltreffendheid vir die spesifieke stowwe was beter. In die evaluering van die nanovesels vir die ekstraksie van die meer polêre suurstofryke stowwe was daar waargeneem dat 2- etielheksielakrilaat die enigste analiet was wat ge-ëkstraeer was deur al die materiale. Die PAN-g- PDMS kon drie van die vier polêre stowwe op vlakke van 100 μg.l-1 opspoor. By laer analietkonsentrasies van 10 μg.l-1 kon slegs twee van die vier akrilaat verbindings opgespoor word deur gebruik te maak van hierdie nanovesels. Etielakrilaat was nie ge-ëkstraeer deur enige van die nuwe materiale nie, terwyl in SFME met die gebruik van die CAR/ PDMS vesel, die analiet op vlakke onder 1 μg.l-1 opgespoor kon word. Alhoewel hierdie nuwe materiale nie beter is as die kommersieel beskikbare ekstraksiemateriale nie is dit net die geval vir die spesifieke teiken analietgroepe wat ondersoek was in hierdie studie.
Masson, Jean-François. "Cellulosesynthetic-polymer blends." Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=74661.
Full textLiu, Jing. "Carbon nanotube/polymer composites and novel micro- and nano-structured electrospun polymer materials." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/22673.
Full textCommittee Chair: Kumar, Satish; Committee Member: Carr, Wallace; Committee Member: Graham, Samuel; Committee Member: Griffin, Anselm; Committee Member: Yao, Donggang.