Dissertations / Theses on the topic 'Polymeric Powders'
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Brink, Andrew E. "The synthesis, stabilization and sintering of high performance semicrystalline polymeric powders." Diss., This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-08062007-094411/.
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Ma, Da. "Improving the Strength of Binder Jetted Pharmaceutical Tablets Through Tailored Polymeric Binders and Powders." Thesis, Virginia Tech, 2020. http://hdl.handle.net/10919/101030.
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Additive Manufacturing (AM) provides a unique opportunity for fabrication of personalized medicine, where each oral dosage could be tailored to satisfy specific needs of each individual patient. Binder jetting, an easily scalable AM technique that is capable of processing the powdered raw material used by tablet manufacturers, is an attractive means for producing individualized pharmaceutical tablets. However, due to the low density of the printed specimens and incompatible binder-powder combination, tablets fabricated by this AM technology suffer from poor strength. The research is introducing an additional composition in the binder jetting powder bed (e.g., powdered sugar) could significantly enhance the compressive strength of the as-fabricated tablets, as compared with those tablets fabricated without the additional powder binding agent. However, no previous research demonstrated comprehensive approaches to enhance the poor performance of the 3D printed tablets. Therefore, the goal of this work is to identify processing techniques for improving the strength of binder jetted tablets, including the use of (i) novel jettable polymeric binders (e.g., 4-arm star polyvinylpyrrolidone (PVP), DI water, and different i) weight percentage of sorbitol binder) and (ii) introducing an additional powder binding agent into the powder bed (e.g.., different wt% of powdered sugar).M.S.
Three-dimensional printing is well-known as 3D printing. 3D printing pills are printed from the 3D printer. As of today, we now stand on the brink of a fourth industrial revolution. By the remarkable technological advancements of the twenty-first century, manufacturing is now becoming digitized. Instead of using a large batch process as traditional, customized printlets with a tailored dose, shape, size, and release characteristics could be produced on- demand. The goal of developing pharmaceutical printing is to reduce the cost of labor, shorten the time of manufacturing, and tailor the pills for patients. And have the potential to cause a paradigm shift in medicine design, manufacture, and use. This paper aims to discuss the current and future potential applications of 3D printing in healthcare and, ultimately, the power of 3D printing in pharmaceuticals.
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Syzdek, Jarosław Sylwester. "Application of modified ceramic powders as fillers for composite polymeric electrolytes based on poly(oxyethylene)." Amiens, 2010. http://www.theses.fr/2010AMIE0102.
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Le premier objectif de cette thèse est l’étude de l’influence de charges inorganiques (additifs) sur les propriétés des électrolytes polymères composites, à base de poly(oxyde d’éthylène) de basses et hautes masses moléculaires. Pour étudier tout les facteurs, nous avons choisi trois oxydes d’aluminium et deux oxydes de titane, distincts de par la taille des grains. Il apparaît exclusivement que les échantillons d’oxyde d’aluminium aux grains de taille micrométrique sont clairement modifiés ; les particules d’oxyde d’aluminium sont plus sensibles au traitement que les oxyde de titane et l’effet est plus marqué pour les particules de taille micrométriques par rapport aux particules nanométriques d’oxyde d’aluminium. Ensuite les poudres (au total 26) étaient utilisées comme charge pour les électrolytes polymères à base de dimétoxy-poly(oxyde d’éthylène) de masse moléculaire moyenne 500 g•mol-1 (liquide à température ambiante) et le poly(oxyde d'éthylène de masse moléculaire moyenne 5•102g•mol-1(solide à température ambiante). Le perchlorate de lithium (LiClO4) a été à chaque fois utilisé comme sel et sa concentration fixée à de 1 mol•kg-1. En résumé – des électrolytes contenant un large panel de poudres ont été étudiés, et il a été montré que les conditions de préparation des électrolytes avec les mêmes matériaux de départ peuvent conduire à l’obtention de matériaux finaux différents. Cela peut expliquer les divergences entre les résultats rapportés dans la littérature ces dernières années. Enfin, l’influence des poudres sur la conductivité et les conditions de son augmentation ont été déterminéesThe primary goal of this work was to study the influence of surface-modified inorganic fillers on the properties of composite polymeric electrolytes based on poly(oxyethylene) of both low and high molecular weight. To study all interesting factors we chose three different aluminas and two titanias characterised by different grain sizes. It appeared that only microsized aluminas are readily modified. Less sensitive to the treatment is nano alumina and the least are titanias. Then obtained powders (26 in total) were applied as fillers for polymeric electrolytes based on poly(oxyethylene) of molecular weight aqual to 500 g•mol-1 (liquid at room temperature) and 5•106 g•mol-1 (liquid at room temperature) and 5•106 g•mol-1(solid at room temperature). Lithium perchlorate was used as a salt, its concentration was fixed to be 1 mol•kg-1. In general, a vast population of samples was prepared and it was shown that starting with the same material, one can obtain totally different products. That can explain many of the discrepancies found in the literature published on this subject over the last 20 years. Apart from that a universal procedure of samples preparation was established and conditions of conductivity improvement determined
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Al-Meshal, Mohammed A. S. "Physicochemical and tableting properties of crystallised and spray-dried phenylbutazone containing polymeric additives : effect of polymeric additives (hydroxypropyl methylcellulose and a polyoxyethylene-polyoxypropylene glycol) on the crystalline structure, physicochemical properties and tableting behaviour of crystallised and spray-dried phenylbutazone powders." Thesis, University of Bradford, 1985. http://hdl.handle.net/10454/4207.
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The physicochemical properties of a drug affect to a large extent its subsequent biological absorption and bioavailability profile. Considerable pharmaceutical interest is therefore directed torwards the improvement of drug dissolution characteristics of drugs with low aqueous solubility. This thesis has considered the controlled modification of drug dissolution profiles by means of incorporating low concentrations of hydrophilic polymers by different processes into a host drug substance. In order to examine this approach and its potential use, the physicochemical, solid state, stability and tableting properties of a poorly aqueous soluble drug, phenylbutazone, in alternative polymorphic form and containing low levels of two hydrophilic polymers - hydroxypropyl methylcellulose (H.P.M.C.) and the surfactant poloxamer 188 - prepared by both conventional crystallisation and spray drying are reported. As an integral nart of the work attempts were mado to identify the different polymorphic forms of phenylbutazone. The δ-form, the commercially available stable form and the α and β metastable forms (nomenclature after Muller, 1978) were isolated. The α form was found to be unstable on storage. A 2 fold increase in intrinsic dissolution rate was observed for the metastable β-polymorph compared with the stable δ-polymorphic form. The effect of crystallisation rate on the formation of polymorphs of phenylbutazone was studied using a mini-spray dryer, and slower rates of crystallisation were found to favour polymorph formation. The hydrophilic polymers, H.P.M.C. and poloxamer 188, were incorporated by conventional crystallisation and spray drying into the drug crystal. Samples were subjected to a series of tests including differential scanning calorimetry, X-ray powder diffraction, scanning electron microscopy, and intrinsic dissolution and solubility. When prepared by conventional crystallisation H.P.M.C. was found to form a "high energy" complex with phenylbutazone which melted 10°C lower than the parent drug. When prepared by spray drying H.P.M.C. inhibited the formation of the metastable β-polymorph of phenylbutazone. A 2 fold increase in intrinsic dissolution rate was observed for crystallised and spray dried samples containing 2% w/w or more added polymer. Poloxamer 188 did not form a complex with phenylbutazone and unlike H.P.M.C. did not inhibit the formation of the β-polymorph. For both crystallised and spray dried samples a 3 fold increase in dissolution rate was obtained at polymer levels of 1% w/w or above. The increase in dissolution has been attributed to facilitated wetting by lowering of interfacial tension rather than through the formation of micelles. The stability of selected phenylbutazone:polymer samples was tested at elevated temperatures. The stability was found to be affected both by the method of sample preparation and the type of additive. Large breakdowns occurring by a hydrolytic effect were identified for the crystallised phenylbutazone samples containing poloxamer 188. The effects on compaction of phenylbutazone in alternative form and presence of polymeric additives were studied by compressing samples of similar particle sizes of phenylbutazone as supplied (δ-form), samples of spray dried phenylbutazone (β-form) and samples containing different concentrations of H.P.M.C. prepared both by conventional crystallisation and spray drying. Compaction data were analysed according to the Heckel relationship and by force transmission ratio as well as from the tensile strengths of prepared tablets. The presence of H.P.M.C. up to 5% w/w concentration in phenylbutazone did not change the mean yield pressure for the crystallised or spray dried samples, although a difference in mean value was observed between the crystallised and spray dried materials, 93.22 MPa and 147.02 MPa respectively. Force transmission was found to be improved for samples containing H.P.M.C. prepared by both techniques and in general, the tablet tensile strengths for crystallised samples containing H.P.M.C. were approximately three times greater than for spray dried samples at equivalent tablet porosity. Differences are attributed to variation in solid state and particulate properties between samples.
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Shokouhi, 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.
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Rammoorthy, Madhusudhan. "On-line consolidation of thermoplastic powder fusion coated filaments." Thesis, Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/11131.
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Cheung, Wai Lam. "Bulking of charged pellets of polymeric materials." Thesis, University of Southampton, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261854.
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Chatham, Camden Alan. "Property-Process-Property Relationships in Powder Bed Fusion Additive Manufacturing of Poly(phenylene sulfide): A Case Study Toward Predicting Printability from Polymer Properties." Diss., Virginia Tech, 2020. http://hdl.handle.net/10919/100053.
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Powder bed fusion (PBF) is one of seven technology modalities categorized under the term additive manufacturing (AM). Beyond the advantages of fabricating complex geometries and the "tool-less manufacturing" paradigm common to all types of AM, polymer PBF shows potential for significant industrial relevance through exploiting the technique's characteristic powder-filled bed (a.k.a. build piston) to utilize the full printer volume for batch-style production. Although PBF should be a suitable processing technique for all semi-crystalline polymers, the polyamide family currently occupies around 90% of the commercial market for polymer PBF. This commercial dominance of polyamides is mirrored in the focus of research publications.
The lack of chemical variety in published research questions the universality of reported Structure-Property-Process and Process-Structure-Property relationships for PBF. This dissertation presents the findings from identifying Structure-Property-Process relationships critical to fabricate multi-layer parts for poly(phenylene sulfide) (PPS) by PBF towards expanding PBF material selection and evaluating universality of relationship guidelines. PPS is an engineering thermoplastic used for its high strength, rigidity, dielectric properties, and chemical resistance at elevated temperatures. These properties are attributed to PPS' highly crystalline morphology. Its current use in the automotive and aerospace industries, which are early adopters of AM technologies, makes PPS a prime candidate for AM applications. Therefore, the goal of this work is to demonstrate PPS printing by PBF, study its behavior throughout the PBF lifecycle, and abstract general trends in polymer PBF relationships.
First, theoretical ranges for print parameter values are determined from properties of an experimental grade PPS powder feedstock. Successful printing of PPS by PBF is demonstrated in a way contrary to published empirical polymer-PBF relationships. Low temperature printing (i.e., bed temperature more than 15 °C lower than polymer peak melting temperature) of PPS successfully fabricated dimensionally accurate parts with reasonable mechanical properties compared against injection molding values. This distinct PPS behavior does not follow empirical guidelines developed for either polyamides or poly(aryl ether ketones).
The unique success of low-temperature PBF prompted further investigation into potential benefits of low-temperature printing. Structure-Property-Process relationships were characterized over the course of simulated powder reuse to show that low-temperature printing prolonged the time when PPS powder properties remained in the "printable" range. Significantly re-used PPS powder was shown to be printable when print parameters were adjusted to accommodate structure and property changes. Successful prints from reused powder is uncommon among published reports of PBF printing of high-performance engineering thermoplastics.
Observations of a change in molecular architecture through branching and crosslinking during simulated powder reuse motivated investigating if similar reactions occur in printed parts. PPS is commonly used at elevated temperatures in the presence of oxygen, which is the ideal environment for branching and crosslinking. Structural changes manifested in increased glass transition temperature and high temperature storage modulus. The relative change in structure when printed parts were thermo-oxidatively exposed was observed to be significant for parts printed from new powder, but minimal for parts printed from reused powder. This is a result of the structural changes occurring as powder feedstock during reuse over multiple builds.
The changing architecture of reused PPS exposed shortcomings with print parameter value selection based solely on polymer thermal properties. Branching and crosslinking reduced crystallinity, resulting in calculated less energy required to melt; however, it also increased melt viscosity. This negative impact on coalescence behavior was not reflected in the methodology for process parameter value determination because current guidelines neglect rheological properties. These observations motivated proposing a method for selecting print settings based on polymer coalescence behavior. Because it is based on coalescence, this method can predict the transition in governing physics from viscous coalescence to bubble diffusion, which is accompanied by a change in the dependence of mechanical properties on laser energy density.
Most work in polymer PBF has focused on "printed part triad'" Process-Property relationships. Work presented in this dissertation contributes to the "printability triad'" of Structure-Property-Process relationships and does so using the novel-to-PBF polymer, PPS. Additional polymers must be explored to continue to discern which polymer-manufacturing relationships are universal among all polymers and which are specific to one subset. The observations and connected interpretation to principles of polymer physics add to the body of knowledge for the polymer PBF field. These contributions will help pave the way for investigations into other polymer families and will re-shape the field's normative logic use when answering the question "what makes a polymer printable by PBF?" Understanding the connection between polymer properties and physical stimuli characteristic of PBF manufacturing will result in parts tailored for specific applications and more sustainable manufacturing, thus realizing additive manufacturing's full potential.Doctor of Philosophy
Powder bed fusion (PBF) is one of seven distinct additive manufacturing (AM, also known as ``3D printing'') technologies. The manufacturing process creates solid, three-dimensional shapes through selectively heating, melting, and fusing together polymer powder particles in a layer-by-layer manner. Currently, organizations are interested in complementing existing manufacturing technology with PBF for one of three general reasons: (1) "complexity is free" PBF has the ability to make shapes that are difficult or expensive to fabricate using other manufacturing technologies. (2) "tool-less manufacturing" PBF only requires a digital design file to fabricate objects. This enables small changes to be easily made via computer-aided design (CAD) programs without the need to invest time and money into tooling (e.g., molds, jigs, fixtures, or other product-specific tools). This enables "mass customized" products (e.g., custom-fit medical devices and implants) to be economically feasible. (3) "material efficiency" AM is attractive as it often generates less waste than subtractive manufacturing techniques like milling. This is particularly a concern for organizations that manufacture parts from expensive, high-performance polymers, such as in the aerospace and medical industries. Despite these benefits, the state of the art for polymer PBF has room for improvement. Specifically, there are many details regarding material behavior during PBF manufacturing that are unknown; any unknown behaviors present challenges to building confidence in production quality. Additionally, approximately 90% of current PBF use is nylon-12 or else another material in the polyamide family of semi-crystalline thermoplastics. This limited selection of commercially available materials compared against other forms of manufacturing contributes to PBF's circular quandary: the manufacturing process physics are not robustly understood because most experimentation and research has been carried out on one family of polymers; however, a wider variety of polymers has not been developed because there is a limited understanding of the process physics. This dissertation presents research toward answering both PBF challenge areas. The first three chapters present investigations into relationships between the properties of a novel, experimental grade poly(phenylene sulfide) (PPS) semi-crystalline thermoplastic polymer powder, the stimuli imposed on this polymer during PBF processing, and the resultant properties of printed parts (i.e., "property-process-property relationships"). The target polymer, poly(phenylene sulfide), is a high-temperature, high-performance polymer that is traditionally melt processed, but has not yet been commercialized for PBF. Prior literature has established mathematical representation for the interaction between manufacturing energy input and the thermal response of the polymer resulting in melting. This framework has been created through studying the polyamide family. Work presented in this dissertation evaluates existing guidelines for PBF process parameter selection using measured thermal behavior of PPS (i.e., a polysulfide, not a polyamide) to predict the range of manufacturing energies affecting geometrically accurate printed parts of high density and strength. In addition, the impact of thermal exposure from repeated PPS powder reuse over the course of multiple PBF prints was evaluated on powder, thermal, and rheological properties identified as critical for PBF printing. Changes to the molecular structure and properties of reused PPS powder were observed to follow different trends than those reported for other materials traditionally used. The effect of thermal exposure on printed parts was also investigated to determine if the observed changes in molecular structure occurring during thermal exposure of the powder would result in changes to mechanical performance properties of printed parts. The importance of rheological flow properties in dictating printed part performance was observed to be a common theme throughout working with PPS. The final chapter presents a novel method for quantitatively predicting particle fusion during PBF and connecting the extent of particle fusion to mechanical properties of printed parts. The presented method is "polymer agnostic" and advances the state of the art in understanding the physics guiding polymer response to stimuli imposed during PBF AM.
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DeBenedictis, Mach Austin. "Model development for the electrostatic fluidized bed powder coating process." Diss., Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/11326.
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Kozielová, Silvie. "Studium flexibility a adheze cementových lepidel při různém stupni modifikace polymerním pojivem." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-392367.
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The content of the diploma thesis deals with the study of the flexibility and adhesion of cement tile adhesives, which are modified by a polymeric additive. The effects of the quantity and type of redispersible polymer powder used on the properties of the adhesives, in particular on the deformability of adhesives and their adhesion, are monitored. The theoretical part summarizes the basic data concerning classification of the ceramic tiles, information about the adhesives, the processed part concerning the polymer modified adhesives and the effects of the polymeric additives on their properties. The practical part deals primarily with the study of adhesion and flexibility of polymer modified adhesives and study of microstructure of selected materials.
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Kunda, N. K. "Dry powder inhalation of pneumococcal vaccine using polymeric nanoparticles as carriers." Thesis, Liverpool John Moores University, 2014. http://researchonline.ljmu.ac.uk/4462/.
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Streptococcus pneumoniae is the leading bacterial cause of pneumococcal diseases, of which pneumonia is the main cause of death amongst the immunocompromised, elderly over the age of 50 and children under the age of 5. Although vaccines such as pneumococcal polysaccharide vaccine 23, pneumococcal conjugate vaccine 7, 10 and 13 are available, they are expensive to produce and distribute. Moreover, the variation in serotype distribution across geographical locations and rise in dominance of disease due to non-vaccine serotype coverage has led to significant attention towards the development of alternate vaccine candidates such as pneumococcal surface protein A (PspA). A potential dry powder vaccine formulation containing polymeric nanoparticles (NPs) adsorbed with PspA4Pro and formulated into nanocomposite microparticles (NCMPs) using L-leucine (L-leu) to be delivered via inhalation was developed. Poly(glycerol adipate-co-ω-pentadecalactone), PGA-co-PDL, NPs with either anionic or cationic surface charge of optimum size (~200-250 nm) to be effectively taken up by the lung dendritic cells (DCs) were successfully produced. The NPs were then surface adsorbed with PspA4Pro (~20 µg of PspA4Pro per mg of NPs) and spray-dried using L-leu as a microcarrier to produce NCMPs with a product yield of 55.55±6.64% for the PspA4Pro adsorbed anionic NPs/NCMPs and 53.98±2.23% for the PspA4Pro adsorbed cationic NPs/NCMPs. The NCMPs produced had a corrugated and wrinkled surface morphology. The aerosol properties of anionic NPs/NCMPs determined using a Next Generation Impactor displayed a fine particle fraction (FPF) of 74.31±1.32% and mass median aerodynamic diameter (MMAD) of 1.70±0.03 μm indicating that the majority of the dose would be deposited in the respirable airways of the lungs. The anionic and cationic PGA-co-PDL NPs upon incubation with DCs for 1 h showed an effective uptake as visualised using confocal microscopy. Furthermore, the anionic NPs/NCMPs were well tolerated by the A549 cell line with a cell viability of 87.01±14.11% at 1.25 mg/ml concentration, whereas the cationic NPs/NCMPs showed a cell viability of 75.76±03.55% at 156.25 µg/ml concentration upon 24 h exposure. The PspA4Pro released from the optimised formulations largely maintained its structure as determined using SDS-PAGE and circular dichroism, and the relative antigenicity measured using ELISA was 0.97±0.20 and 0.85±0.05 for anionic and cationic formulations, respectively. Overall, the results obtained indicate the use of these NPs as novel carriers for pulmonary vaccine delivery against pneumococcal diseases.
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Agirtopcu, Yasin. "Investigations On The Permeability Of Acrylic Powder Structures." Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/4/1045343/index.pdf.
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There are many examples where creation and usage of porous substrates
play important roles in various fields of application in material science and
technology. In the manufacture of ceramic products, as an alternative to the plaster molds, porous resin molds are used in order to resolve the drawbacks that result A porous substrate can be produced by various ways. In this study, porous polymeric matrices of poly(methyl methacrylate) (PMMA) and poly(methyl methacrylate-co-2-hydroxyethyl methacrylate) [poly(MMA-HEMA)] polymers were prepared by connecting the polymer microspheres to each other by an epoxy adhesive. To improve the surface properties, methyl methacrylate (MMA) was copolymerized with 2-hydroxyethyl methacrylate (HEMA). The microspheres used were synthesized by suspension polymerization and characterization was
done by Nuclear Magnetic Resonance (NMR), Particle Size Analyzer and
Scanning Electron Microscope (SEM). The porous samples were prepared with
PMMA and poly(MMA-HEMA) copolymer microspheres with two different HEMA contents and their surface energies were measured. In addition, the effect of mean particle diameter of the microspheres used and the epoxy content of the solution used to bind the microspheres, on the impregnation capacity, morphology
and the impact strength of the porous samples prepared, were studied.
Inclusion of HEMA into the formulation improved the impregnation capacity of the samples. Using microspheres with narrower particle size distribution resulted in larger representative capillary radii and higher rate of impregnation of the samples. Increasing the epoxy content of the solution used to bind the beads, increased the impact strengths of the samples prepared.
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Tuli, Rinku. "Studies on the surface properties of biodegradable polymer carriers in respiratory delivery of drug from Dry Powder Inhaler formulations." Thesis, Queensland University of Technology, 2012. https://eprints.qut.edu.au/53295/1/Rinku_Tuli_thesis.pdf.
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Dry Powder Inhaler (DPI) technology has a significant impact in the treatment of various respiratory disorders. DPI formulations consist of a micronized drug (<5ìm) blended with an inert coarse carrier, for which lactose is widely used to date. DPIs are one of the inhalation devices which are used to target the delivery of drugs to the lungs. Drug delivery via DPI formulations is influenced by the physico-chemical characteristics of lactose particles such as size, shape, surface roughness and adhesional forces. Commercially available DPI formulations, which utilise lactose as the carrier, are not efficient in delivering drug to the lungs. The reasons for this are the surface morphology, adhesional properties and surface roughness of lactose. Despite several attempts to modify lactose, the maximum efficient drug delivery to the lungs remains limited; hence, exploring suitable alternative carriers for DPIs is of paramount importance. Therefore, the objective of the project was to study the performance of spherical polymer microparticles as drug carriers and the factors controlling their performance.
This study aimed to use biodegradable polymer microspheres as alternative carriers to lactose in DPIs for achieving efficient drug delivery into the lungs. This project focused on fabricating biodegradable polymer microparticles with reproducible surface morphology and particle shape. The surface characteristics of polymeric carriers and the adhesional forces between the drug and carrier particles were investigated in order to gain a better understanding of their influence on drug dispersion. For this purpose, two biodegradable polymers- polycaprolactone (PCL) and poly (DL-lactide-co-glycolide) (PLGA) were used as the carriers to deliver the anti-asthmatic drug - Salbutamol Sulphate (SS).
The first study conducted for this dissertation was the aerosolization of SS from mixtures of SS and PCL or PLGA microparticles. The microparticles were fabricated using an emulsion technique and were characterized by laser diffraction for particle size analysis, Scanning Electron Microscopy (SEM) for surface morphology and X-ray Photoelectron Spectroscopy (XPS) to obtain surface elemental composition. The dispersion of the drug from the DPI formulations was determined by using a Twin Stage Impinger (TSI). The Fine particle Fraction (FPF) of SS from powder mixtures was analyzed by High Performance Liquid Chromatography (HPLC). It was found that the drug did not detach from the surface of PCL microspheres. To overcome this, the microspheres were coated with anti-adherent agents such as magnesium stearate and leucine to improve the dispersion of the drug from the carrier surfaces. It was found that coating the PCL microspheres helped in significantly improving the FPF of SS from the PCL surface. These results were in contrast to the PLGA microspheres which readily allowed detachment of the SS from their surface. However, coating PLGA microspheres with antiadherent agents did not further improve the detachment of the drug from the surface. Thus, the first part of the study demonstrated that the surface-coated PCL microspheres and PLGA microspheres can be potential alternatives to lactose as carriers in DPI formulations; however, there was no significant improvement in the FPF of the drug.
The second part of the research studied the influence of the size of the microspheres on the FPF of the drug. For this purpose, four different sizes (25 ìm, 48 ìm, 100 ìm and 150 ìm) of the PCL and PLGA microspheres were fabricated and characterized. The dispersion of the drug from microspheres of different sizes was determined. It was found that as the size of the carrier increased there was a significant increase in the FPF of SS. This study suggested that the size of the carrier plays an important role in the dispersion of the drug from the carrier surface.
Subsequent experiments in the third part of the dissertation studied the surface properties of the polymeric carrier. The adhesion forces existing between the drug particle and the polymer surfaces, and the surface roughness of the carriers were quantified using Atomic Force Microscopy (AFM). A direct correlation between adhesion forces and dispersion of the drug from the carrier surface was observed suggesting that adhesion forces play an important role in determining the detachment potential of the drug from the carrier surface. However, no direct relationship between the surface roughness of the PCL or PLGA carrier and the FPF of the drug was observed.
In conclusion, the body of work presented in this dissertation demonstrated the potential of coated PCL microspheres and PLGA microspheres to be used in DPI formulations as an alternative carrier to sugar based carriers. The study also emphasized the role of the size of the carrier particles and the forces of interaction prevailing between the drug and the carrier particle surface on the aerosolization performances of the drug.
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Bouscher, Robert F. "Advancements in Powder Coating Processing and in Real-time Film Formation Analysis of Thermoset Coatings." University of Akron / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=akron1627566578541715.
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Azhdar, Bruska. "Improved high velocity cold copaction processing : polymer powder to high performance parts." Licentiate thesis, KTH, Polymer Technology, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-407.
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A uniaxial High-Velocity Compaction (HVC) process for polymer powder using a cylindrical, hardened steel die and a new technique with relaxation assist was tested with a focus on the compactibility characteristics and surface morphology of the compacted materials using various heights of relaxation assist device with different compacting profiles.
Relaxation assist device was presented as a new technique to reduce springback, pull-out phenomenon and to improve the compaction process.
The basic phenomena associated with HVC are explained and the general energy principle is introduced to explain pull-out phenomenon during the decompacting stage. In this study, polyamide-11 powders with different particle size distributions have been compacted with the application of different compaction profiles, e.g. different energies and velocities. It was found that the relative green density is influenced more by the pre-compacting (primary compaction step) than by the post-compacting (secondary compaction step).
Experimental results for different compaction profiles were presented showing the effect of varying the opposite velocity during the decompacting stage and how to improve the homogeneous densification between the upper and lower surface and the evenness of the upper surface of the compacted powder bed by using relaxation assists, and the influences of the relaxation assist device on the process characteristics. It was found that the relaxation assist improves the compaction of the polymer powder by locking the powder bed in the compacted form. In addition, the relative times of the compacting stage, decompacting stage and the reorganisation of the particles can be controlled by altering the height of the relaxation assist. It was found that the high-velocity compaction process is an interruption process and that the delay times between the pressure waves can be reduced by increasing the height of the relaxation assist device. Furthermore, the first gross instantaneous springback and the total elastic springback are reduced.
Two bonding strain gauges and a high-speed video camera system were used to investigate the springback phenomenon during the compaction process. Scanning electron microscopy (SEM) and image computer board Camera (IC-PCI Imaging Technology) were used to the study the morphological characteristics, the limit of plastic deformation and particle bonding by plastic flow at contact points, and pull-out phenomena.
QC 20100506
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Neel, Christopher Holmes. "Shock compression of a heterogeneous, porous polymer composite." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34689.
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Hasheminasab, S. Abed. "Bismaleimide Methacrylated Polyimide-Polyester Hybrid UV-Curable Powder Coating." University of Akron / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=akron1586906287945286.
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Kandis, Mouhyieldin. "Observation and modeling of part growth and shape evolution of polymer parts produced by non-isothermal and laser-induced sintering of powders /." Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.
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Fan, Kin-ming, and 范健明. "Heat transfer properties and fusion behaviour of polymer based composite powders in selective laser sintering." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B31245286.
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Nguyen, Hanh. "Surface modification of hydrophobic drugs by adsorption of hydrophilic polymers." Thesis, University of Sunderland, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.300329.
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Azhdar, Bruska. "Novel Technique to Improve High-Velocity Cold Compaction : Processing of Polymer Powders and Polymer-Based Nanocomposite High Performance Components." Doctoral thesis, Stockholm : Department of Fiber and Polymer Technology, Chemical Science and Engineering, Royal Institute of Technology, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4133.
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Yildirim, Ismail. "Surface Free Energy Characterization of Powders." Diss., Virginia Tech, 2001. http://hdl.handle.net/10919/27525.
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Microcalorimetric measurements and contact angle measurements were conducted to study the surface chemistry of powdered minerals. The contact angle measurements were conducted on both flat and powdered talc samples, and the results were used to determine the surface free energy components using Van Oss-Chaudhury-Good (OCG) equation. It was found that the surface hydrophobicity of talc increases with decreasing particle size. At the same time, both the Lifshitz-van der Waals (gSLW) and the Lewis acid-base (gSAB) components (and, hence, the total surface free energy (gS)) decrease with decreasing particle size. The increase in the surface hydrophobicity and the decrease in surface free energy (gS) can be attributed to preferential breakage of the mineral along the basal plane, resulting in the exposure of more basal plane surfaces to the aqueous phase.
Heats of immersion measurements were conducted using a flow microcalorimeter on a number of powdered talc samples. The results were then used to calculate the contact angles using a rigorous thermodynamic relation. The measured heat of immersion values in water and calculated contact angles showed that the surface hydrophobicity of talc samples increase with decreasing particle size, which agrees with the direct contact angle measurements. A relationship between advancing water contact angle qa, and the heat of immersion (-DHi) and surface free energies was established. It was found that the value of -DHi decrease as qa increases.
The microcalorimetric and direct contact angle measurements showed that acid-base interactions play a crucial role in the interaction between talc and liquid. Using the Van Oss-Chaudhury-Goodâ s surface free energy components model, various talc powders were characterized in terms of their acidic and basic properties. It was found that the magnitude of the Lewis electron donor, gS-, and the Lewis electron acceptor, gS+, components of surface free energy is directly related to the particle size. The gS- of talc surface increased with decreasing particle size, while the gS+ slightly decreased. It was also found that the Lewis electron-donor component on talc surface is much higher than the Lewis electron-acceptor component, suggesting that the basal surface of talc is basic.
The heats of adsorption of butanol on various talc samples from n-heptane solution were also determined using a flow microcalorimeter. The heats of adsorption values were used to estimate % hydrophilicity and hydrophobicity and the areal ratios of the various talc samples. In addition, contact angle and heat of butanol adsorption measurements were conducted on a run-of-mine talc sample that has been ground to two different particle size fractions, i.e., d50=12.5 mm and d50=3.0 mm, respectively. The results were used to estimate the surface free energy components at the basal and edge surfaces of talc. It was found that the total surface free energy (gS) at the basal plane surface of talc is much lower than the total surface free energy at the edge surface. The results suggest also that the basal surface of talc is monopolar basic, while the edge surface is monopolar acidic. The results explain why the basicity of talc surface increases with decreasing particle size as shown in the contact angle and microcalorimetric measurements.
Furthermore, the effects of the surface free energies of solids during separation from each other by flotation and selective flocculation were studied. In the present work, a kaolin clay sample from east Georgia was used for the beneficiation tests. First, the crude kaolin was subjected to flotation and selective flocculation experiments to remove discoloring impurities (i.e., anatase (TiO2) and iron oxides) and produce high-brightness clay with GE brightness higher than 90%. The results showed that a clay product with +90% brightness could be obtained with recoveries (or yields) higher than 80% using selective flocculation technique. It was also found that a proper control of surface hydrophobicity of anatase is crucially important for a successful flotation and selective flocculation process. Heats of immersion, heats of adsorption and contact angle measurements were conducted on pure anatase surface to determine the changes in the surface free energies as a function of the surfactant dosage (e.g. hydroxamate) used for the surface treatment. The results showed that the magnitude of the contact angle and, hence, the surface free energy and its components on anatase surface varies significantly with the amount of surfactant used for the surface treatment.Ph. D.
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Lone, Ashfaq Hussain. "Engineering and durability properties of concrete modified by redispersible polymer powder." Thesis, University of Sheffield, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.420813.
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Nugent, Paul James. "A study of heat transfer and process control in the rotational moulding of polymer powders." Thesis, Queen's University Belfast, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317138.
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Das, Ajay Kumar. "An investigation on the printing of metal and polymer powders using electrophotographic solid freeform fabrication." [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0005385.
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Elversson, Jessica. "Spray-Dried Powders for Inhalation : Particle Formation and Formulation Concepts." Doctoral thesis, Uppsala University, Department of Pharmaceutical Chemistry, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-5904.
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Spray drying is a method with a high potential in the preparation of protein particles suitable for pulmonary delivery. However, surface induced denaturation of bio-molecules during atomization and subsequent drying can be substantial and it is therefore important to develop new formulation concept for concurrent encapsulation and stabilization of proteins during spray drying. Hence, with an overall objective to increase the knowledge of the formation of particulate systems for systemic administration of proteins by spray drying, the first part of this thesis, systematically investigated the particle formation by droplet size and particle size measurements. It was described how specific properties, such as the solubility and the crystallization propensity of the solute, can affect the product, e.g. the particle size, internal structures, and possibly particle density. A new method using atomic force microscopy (AFM) for the assessment of the effective particle density of individual spray-dried particles was demonstrated. In the second part, two different formulation concepts for encapsulation of protein during spray drying were developed. Both systems used non-ionic polymers for competitive adsorption and displacement of protein from the air/water interface during spray drying. The aqueous two-phase system (ATPS) of polyvinyl alcohol (PVA) and dextran, and the surface-active polymers, hydroxypropyl methylcellulose (HPMC) and triblock co-polymer (poloxamer 188) used for in situ coating, proved efficient in encapsulation of a model protein, bovine serum albumin (BSA). Inclusion of polymeric materials in a carbohydrate matrix also influenced several particle properties, such as the particle shape and the surface morphology, and was caused by changes in the chemical composition of the particle surface and possibly the surface rheology. In addition, powder performance of pharmaceutical relevance, such as dissolution and flowability, were affected.
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Azhdar, Bruska. "Improved high velocity cold compaction processing : Polymer powder to high performance parts /." Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-407.
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Kong, Xiangji. "Development and characterization of polymer- metallic powder feedstocks for micro-injection molding." Phd thesis, Université de Franche-Comté, 2011. http://tel.archives-ouvertes.fr/tel-00844736.
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Micro-Powder Injection Moulding (Micro-PIM) technology is one of the key technologies that permit to fit with the increasing demands for smaller parts associated to miniaturization and functionalization in different application fields. The thesis focuses first on the elaboration and characterization of polymer-powder mixtures based on 316L stainless steel powders, and then on the identification of physical and material parameters related to the sintering stage and to the numerical simulations of the sintering process. Mixtures formulation with new binder systems based on different polymeric components have been developed for 316L stainless steel powders (5 µm and 16 µm). The characterization of the resulting mixtures for each group is carried out using mixing torque tests and viscosity tests. The mixture associated to the formulation comprising polypropylene + paraffin wax + stearic acid is well adapted for both powders and has been retained in the subsequent tests, due to the low value of the mixing torque and shear viscosity. The critical powder volume loading with 316L stainless steel powder (5 µm) according to the retained formulation has been established to 68% using four different methods. Micro mono-material injection (with 316L stainless steel mélange) and bi-material injection (with 316L stainless steel mélange and Cu mélange) are properly investigated. Homogeneity tests are observed for mixtures before and after injection. A physical model well suited for sintering stage is proposed for the simulation of sintering stage. The identification of physical parameters associated to proposed model are defined from the sintering stages in considering 316L stainless steel (5 µm)mixtures with various powder volume loadings (62%, 64% and 66%). Beam-bending tests and free sintering tests and thermo-Mechanical-Analyses (TMA) have also investigated. Three sintering stages corresponding to heating rates at 5 °C/min, 10 °C/min and 15 °C/min are used during both beam-bending tests and free sintering tests. On basis of the results obtained from dilatometry measurements, the shear viscosity module G, the bulk viscosity module K and the sintering stress σs are identified using Matlab® software. Afterwards, the sintering model is implemented in the Abaqus® finite element code, and appropriate finite elements have been used for the support and micro-specimens, respectively. The physical material parameters resulting from the identification experiments are used to establish the proper 316L stainless steel mixture, in combination with G, K and σs parameters. Finally, the sintering stages up to 1200 °C with three heating rates (5 °C/min, 10 °C/min and 15 °C/min) are also simulated corresponding to the four micro-specimen types (powder volume loading of 62%, 64% and 66%). The simulated shrinkages and relative densities of the sintered micro-specimens are compared to the experimental results indicating a proper agreement
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Liu, Xin. "Numerical modeling and simulation of selective laser sintering in polymer powder bed." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEI012/document.
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La fabrication additive est l’un des secteurs industriels les plus en développent ces dernières années. L’une de ces technologies de fabrication les plus prometteuses est la fusion laser sélective (SLS), et relève d’un intérêt croissant aussi bien industriel qu’académique. Néanmoins, beaucoup de phénomène mis en jeu par ce procédé demeure non encore bien compris, entravant ainsi son développement pour la production de pièces de bonne qualité pour des applications industrielles. L’objectif de cette thèse est de développer un cadre de simulation numérique permettant la simulation du procédé SLS pour des poudres de polymère afin de comprendre les multiples et complexes phénomènes physiques qui se produise lors du frittage laser et d’étudier l’influence des paramètres du procédé sur la qualité du produit final. Contrairement aux approches classiques de modélisation numérique, basées sur la définition de matériaux homogène équivalents pour la résolution des équations de bilan, nous proposons une simulation globale du procédé du frittage laser de poudres, en utilisant la méthode des Eléments Discrets (DEM). Cela consiste en un couplage entre quatre sous-modèles : transferts radiatif dans le milieu granulaire semi-transparent, conduction thermique dans les milieux discrets, coalescence puis densification. Le modèle de transferts par rayonnement concerne l’interaction du faisceau laser avec le lit de poudre. Plusieurs phénomènes sont ainsi pris en compte, notamment la réflexion, la transmission, l’absorption et la réfraction. De plus, une méthode de Monte-Carlo couplée à la méthode du Lancer de rayons est développée afin d’étudier l’influence de la réfraction sur la distribution de l’énergie du laser dans le lit de poudre. Le modèle de conduction dans des milieux discrets décrit la diffusion thermique inter-particules. Finalement, le modèle de frittage décrit les cinétiques de coalescence et de diffusion de l’air dans le polymère et densification du milieu. Cela permet de décrire les cinétiques de fusion des grains, dont l’énergie de surface et la diffusons de l’air sont les deux moteurs principaux. Le couplage entre les différents modèles nous a permis de proposer un modèle numérique global, validé grâce à des comparaisons à des résultats de simulations théoriques et expérimentales, trouvés dans la littérature. Une analyse paramétrique est alors proposée pour la validation du modèle et l’étude du procédé. L’influence de différents paramètres aussi bien du procédé que du matériau sur le champ de température, la densité relative du matériau sa structure, etc , est ainsi investiguée. Les résultats montrent une bonne précision dans la modélisation des différents phénomènes complexes inhérents à ce procédé, et ce travail constitue un potentiel réel pour la modélisation et l’optimisation des procédés de fabrication additive par matériaux granulairesMany industrial and academic interests concerning the additive manufacturing processes are developed in the last decades. As one of the most promising technique of additive manufacturing, the Selective Laser Sintering (SLS) has been valued by both industry and academic. However, it remains that several phenomena are still not well understood in order to properly model the process and propose quality improvement of parts made. The goal of this Ph.D. project is to develop a framework of numerical simulation in order to model the SLS process in polymer powder bed, meanwhile understanding multiple physical phenomena occurring during the process and studying the influence of process parameters on the quality of final product. In contrast to traditional approach, based on the equivalent homogeneous material in numerical modeling of partial differential equations derived from conservation laws, we propose a global model to simulate powder-based additive manufacturing by using the Discrete Element method (DEM). It consists in a coupling between four different physical models: radiative heat transfer, discrete heat conduction, sintering and granular dynamics models. Firstly, the submodel of radiative heat transfer concerns the interaction between the laser beam and powder bed. Several phenomena are considered, including the reflection, transmission, absorption and scattering. Besides, a modified Monte Carlo ray-tracing method is developed in order to study the influence of scattering on the distribution of the deposited laser energy inside the powder bed Furthermore, the submodel of discrete heat conduction describes the inter-particles heat diffusion. Moreover, the sintering submodel concerns the phenomena of coalescence and air diffusion. It describes the melting kinetics of grains, driven by surface tension and the release of entrapped gases inside powder bed. Finally, the granular dynamics submodel concerns the motions and contacts between particles when depositing a new layer of powders. The coupling between these submodels leads to propose a global numerical framework, validated by comparing the results to both simulated and experimental ones from literatures. A parametric study is then proposed for model validation and process analysis. The Influence of different material and process parameters on the evolution of temperature, relative density and materials structure and characteristics are investigated. The results exhibit accurate modeling of the complex phenomena occurring during the SLS process, and the work constitute a great potential in modeling and optimization of additive processes
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Hupfeld, Tim [Verfasser], and Stephan [Akademischer Betreuer] Barcikowski. "Nanoparticle-functionalized polymers for laser powder bed fusion / Tim Hupfeld ; Betreuer: Stephan Barcikowski." Duisburg, 2021. http://d-nb.info/1237221455/34.
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Grosvenor, Martin Paul. "The physico-mechanical properties of electrostatically deposited polymers for use in pharmaceutical powder coating." Thesis, Online version, 1991. http://ethos.bl.uk/OrderDetails.do?did=1&uin=uk.bl.ethos.303452.
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Schultz, Jeffrey Patrick. "Modeling Heat Transfer and Densification during Laser Sintering of Viscoelastic Polymers." Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/11091.
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Laser sintering (LS) is an additive manufacturing process which uses laser surface heating to induce consolidation of powdered materials. This work investigates some of the process-structure-property relationships for LS of viscoelastic polymers. A one-dimensional closed-form analytical solution for heating of a semi-infinite body, with a convective boundary condition, by a moving surface heat flux was developed. This solution approximates the shape of the Gaussian energy distribution of the laser beam more accurately than previous solutions in the literature. A sintering model that combines the effects of viscoelastic deformation driven by attractive surface forces and viscous flow driven by curvature-based forces was developed. The powder-bed temperature was approximated using the thermal model developed herein. The effect of the enthalpy of melting for semi-crystalline polymers was accounted for using a temperature recovery approach. Time-temperature superposition was used to account for the temperature dependence of the tensile creep compliance. The results of the combined-mechanism sintering model will be compared to the classic Mackenzie-Shuttleworth sintering model. A lab-scale LS unit was constructed to fabricate test specimens for model validation and to test the applicability of materials to LS. In this work, sintering four materials, polycarbonate (PC) and three molecular weights of polyethylene-oxide (PEO) was predicted using the aforementioned thermal and sintering models. Samples were fabricated using the lab-scale LS unit and the sintered microstructures were investigated using scanning electron microscopy. The rheologic, thermal and physical properties of the materials were characterized using standard methods and the relevant properties were used in the models. The choice of an amorphous polymer, PC, and a semi-crystalline polymer, PEO, affords comparison of the effects of the two material forms on contact growth during LS. The three molecular weights of PEO exhibit significantly different tensile creep compliances, however, the thermal and physical properties are essentially the same, and therefore the effect of molecular weight and subsequently the rheologic characteristics on contact growth during LS will be investigated. The effects of particle size, laser power, and bed temperature were also investigated.Ph. D.
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Yarmolenko, O. V., A. V. Yudina, G. Z. Tulibaeva, A. V. Cherniak, V. I. Volkov, and A. F. Shestakov. "Influence of Inorganic Nano-powders on the Structure and Conductive Properties of the Network Polymer Electrolytes for Lithium Batteries." Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35511.
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The paper describes investigation on the network polymer electrolytes based on polyethylene glycol diacrylates
and polyester diacrylates PEDA with introduction the nanopowders TiO2, Li2TiO3 and SiO2, with
different size and shape. Much attention is paid to effects of nanoparticles additives on the ionic conductivity
of network polymer electrolytes. The work is aimed to explanation of the mechanism of additives action
on Li+ - ion transport and structural changes of the polymer chains and the solvent molecules. For these
purposes the NMR method with rotation under a magic corner on nuclei 1H and NMR method with a pulsed
magnetic field gradient at the nuclei 7Li were used.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35511
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Kowalski, Sebastian. "Rheology based investigation of a polymer-mineral powder mix for low pressure injection moulding." Limoges, 2005. http://aurore.unilim.fr/theses/nxfile/default/80dadd89-fb07-4918-8b88-5fd642b79cac/blobholder:0/2005LIMO0015.pdf.
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La pâte céramique étudiée, mélange de plusieurs polymères immiscibles : paraffine, EVA, cire de carnauba et d'une poudre minérale submicronique est utilisée dans le procédé d'injection. On s'est surtout attaché à corréler les propriétés rhéologiques à 130°C à la physico-chimie du system. Plusieurs paramètres ont été modifiés, - la fraction volumique, la composition du mélange de polymères et la nature de la poudre. On a montré que les molécules d'EVA et de carnauba sont adsorbées sur la surface de ZrO2, dans un rapport volumique de 2/1 et la poudre fait des inclusions dans la paraffine. Pour une fraction volumique >50% vol. , la pâte se comporte comme un solide et montre des propriétés de thixotropie – analysées avec un modèle développé par Piau. Un rhéomètre capillaire a été utilisé pour estimer la viscosité élongationelle, qui est très sensible (contraire à la viscosité de cisaillement), et clairement lié à la quantité d'EVA adsorbé. The rheological properties of a ceramic paste, comprising several immiscible polymers : paraffin wax, EVA, carnauba wax, mixed with a mineral submicronic powder were investigated at 130°C. It is a prerequisite to master a forming process such as injection moulding and this was one of the pursued objectives. The other one was to relate these properties to the physico-chemical composition. Several parameters were modified i. E. - the vol. Solid fraction, the polymer blend composition and the nature of the powder. It was proved that EVA and carnauba molecules adsorb on ZrO2 surface, in a volume ratio 2/1 and the powder makes inclusions in the liquid paraffin. For a vol. Fraction >50%, a solid-liquid transition occurs - paste shows a thixotropic behaviour-analyzed with a model developed by Piau. A capillary rheometer was used to estimate the extensional viscosity, which is very sensitive (contrary to shear viscosity), and clearly related to the amount of adsorbed EVA
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Sajja, Mani Bhushan. "Eco-friendly paving blocks from alkali-activation of basalt powder." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019.
Find full textAbstract:
The main aim of the research is to investigate the waste by-products as a sustainable construction material by means of Alkali-activation processes. Nowadays, cement is one of the most significant factors of climate change and global warming. It accounts for 5% to 8% of total emission, which may increase due to the increase in concrete production. In this process, sustainable and eco-products have been chosen.
Basalt and metakaolin were chosen as precursors. In this, basalt is the main component of our research. Basalt is an igneous rock formed by the rapid cooling of lava at the surface of a planet and it is the most common rock in the earth’s crust and metakaolin is the anhydrous calcined form of the clay mineral kaolinite also the particle size of metakaolin is smaller than cement particles.
In this experimentation, there are two activators sodium silicate and sodium hydroxide. These two activators added into precursors in certain proportions and mixed using a cement rotator. After that, this mixture is distributed into cube blocks and leave for a few minutes before packing with a plastic cover. Proceeding into a curing process, these cube blocks placed in the oven at certain temperatures between 60 to 80 degrees.
These types of precursors and activators are added in different ratios using this procedure to make a cube sample following by the curing process of 28 days. These were tested in compressive strength machine to obtain load resistance results. Basalt has better chemical resistance to the extended operating temperature range and environmentally friendly material. Metakaolin is eco-friendly by reducing the amount of 〖co〗_2 emission and the heat of hydration leading to shrinkage and crack control.
With the obtained synthetic mixtures, some special paving blocks were produced. Following the EN 1338 standard, these were tested in different to fully characterize the final product.
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Cano, Camilo I. "Polyimide Microstructures From Powdered Precursors: Phenomenological and Parametric Studies on Particle Inflation." Akron, OH : University of Akron, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=akron1123710711.
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Dissertation (Ph.D.)--University of Akron, Dept. of Polymer Engineering, 2005."August, 2005." Title from electronic dissertation title page (viewed 09/24/2005) Includes bibliographical references.
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Shen, Yubin. "The chemical and mechanical behaviors of polymer / reactive metal systems under high strain rates." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45804.
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As one category of energetic materials, impact-initiated reactive materials are able to release a high amount of stored chemical energy under high strain rate impact loading, and are used extensively in civil and military applications. In general, polymers are introduced as binder materials to trap the reactive metal powders inside, and also act as an oxidizing agent for the metal ingredient. Since critical attention has been paid on the metal / metal reaction, only a few types of polymer / reactive metal interactions have been studied in the literature. With the higher requirement of materials resistant to different thermal and mechanical environments, the understanding and characterization of polymer / reactive metal interactions are in great demand. In this study, PTFE (Polytetrafluoroethylene) 7A / Ti (Titanium) composites were studied under high strain rates by utilizing the Taylor impact and SHPB tests. Taylor impact tests with different impact velocities, sample dimensions and sample configurations were conducted on the composite, equipped with a high-speed camera for tracking transient images during the sudden process. SHPB and Instron tests were carried out to obtain the stress vs. strain curves of the composite under a wide range of strain rates, the result of which were also utilized for fitting the constitutive relations of the composite based on the modified Johnson-Cook strength model. Thermal analyses by DTA tests under different flow rates accompanied with XRD identification were conducted to study the reaction mechanism between PTFE 7A and Ti when only heat was provided. Numerical simulations on Taylor impact tests and microstructural deformations were also performed to validate the constitutive model built for the composite system, and to investigate the possible reaction mechanism between two components. The results obtained from the high strain rate tests, thermal analyses and numerical simulations were combined to provide a systematic study on the reaction mechanism between PTFE and Ti in the composite systems, which will be instructive for future energetic studies on other polymer / reactive metal systems.
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Otto, Christian [Verfasser], and Volker [Akademischer Betreuer] Abetz. "Electrically Conductive Composite Materials from Carbon Nanotube Decorated Polymer Powder Particles / Christian Otto ; Betreuer: Volker Abetz." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2017. http://d-nb.info/1150183748/34.
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Jankech, Filip. "Elastomerní plniva jako potencální surovina pro betony a malty." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-295668.
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To attain a sustainable development in the field of building materials, it is necessary to consider environmental, economic, and social aspects of the industrial production. This thesis addresses the first two aspects. Both theoretical and practical research were implemented in order to study the possibility to replace the commonly used RDPs, that are being used in the dry-mix mortar industry as a primary additive, with the industrially processed elastomer waste materials, such as recycled tire rubber. The review of the scientific literature processed within the theoretical research discloses the state of the art in the field of polymer modification of the mortar products and the effect of the commonly used modifiers and elastomer fillers on the performance of mortar and concrete products. The experimental research was implemented to study the possibility of the replacement of the RDPs for the elastomer fillers. The performance of fresh and hardened mortar containing various amounts of elastomer particles was studied. The results indicate, that the partial replacement could be feasible without worsening the performance of the product.
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Janíček, Vít. "Studium vlhkostně-transportních vlastností polymer-cementových stěrek pro vnější kontaktní zateplovací systémy budov." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-392337.
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This diploma thesis deals with study of the moisture-transport properties of polymer cementious ETICS mortars at different doses of redispersible polymer powder. The effect of aerate on these screeds is also investigated. The thesis also evaluates the effect of use various external surface treatments due to risk of cumulate moisture in the perimeter structure.
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Westbeld, Julius. "Investigation of support structures of a polymer powder bed fusion process by use of Design of Experiment (DoE)." Thesis, KTH, Lättkonstruktioner, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-243867.
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In this thesis, support structures of a polymer powder based process called XXXXXXXX™ are examined. These structures are crucial for most additive manufacturing processes. The effects of several factors on five industrially important characteristics of support structures are examined by use of the Design of Experiment (DoE) method. It describes the planning as well as the analysis of the experiments. The experiments are planned in a fractional factorial 211-5 design with 64 specimens, resulting in a resolution of IV. The analysis of the data is done by use of the ANOVA method, with which the significance of effects and interaction effects are checked.I detta examensarbete undersöks stödstrukturer för en polymer-pulverbaserad process kallad XXXXXXXX. Dessa strukturer är väsentliga för de flesta aditiv tillverkning. Med hjälp av metoden "Design of Experiment" (DoE) undersöks effekten av flera faktorer på fem industriellt viktiga egenskaper för stödstrukturer. DoE beskriver både planeringen och analysen av experiment. Experimenten planeras i en fraktionerad faktoriell 211-5 design med 64 provexemplar vilket resulterar i en upplösning av IV. Dataanalysen genomförs med hjälp av ANOVA-metoden, med vilken signifikansen av effekter och interaktionseffekter kan undersökas.
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Muhsin, Mohammad Didare Alam. "Preparation and in vitro evaluation of a polymer based controlled release dry powder inhaler formulation for pulmonary delivery." Thesis, Queensland University of Technology, 2014. https://eprints.qut.edu.au/71806/1/Mohammad%20Didare%20Alam_Muhsin_Thesis.pdf.
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This thesis described the synthesis of an L-leucine conjugate of the biodegradable polymer, chitosan and its potential application for the development of controlled release nanoparticulate dry powder inhaler (DPI) formulations. The study demonstrated that the physicochemical properties of conjugated chitosan nanoparticles had favourable effects on the dispersibility and controlled release profile of a model drug. The toxicity profile of the nanoparticulate formulation revealed promising outcome for its use in pulmonary delivery. The chitosan conjugate produced in this project would be useful for the application of polymer nanoparticulate systems for efficient lung delivery of drugs.
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Zakharova, K., A. Mednikova, V. Rumyantsev, and T. Genusova. "Synthesis of Boron Carbide from Boric Acid and Carbon-Containing Precursors." Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35601.
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The paper compares low-temperature techniques for boron carbide synthesis. Boron carbide was syn-thesized via reaction between boric acid and various carbon precursors, e.g. phenol-formaldehyde resin, su-crose, carbon black, and potato starch. Initial compositions and carbon precursor preparation techniques were selected for synthesis. The resulting products were characterized by IR spectrometry, X-ray diffrac-tion (XRD) and scanning electron microscopy. Possible boron carbide yields up to 95 % of the theoretical yield as calculated from initial boron contents at temperatures of 1550 oС were demonstrated. XRD con-firmed that the synthesized boron carbide (B4C) has a rhombohedral crystalline structure. Final product morphology may be tailored, ranging from isometric to needle-like crystallite morphology. Nanopowders as processed via high-energy milling may be further used as sintering additive for processing of boron carbide ceramics.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35601
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Lambrechts, Jacobus Johannes. "Investigation into the influence of different Kollidon® polymers on the properties of powder mixtures intended for tableting / Jacobus Johannes Lambrechts." Thesis, North-West University, 2008. http://hdl.handle.net/10394/2877.
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α-Lactose monohydrate is one of the oldest fillers used for production of solid dosage forms. Lactose was used as filler in this study, as it is readily available and relatively cheap. Lactose is not directly compressible, but it was one of the first fillers to be modified or co-processed into a direct compressible filler. Tablettose® and Ludipress® are examples of co-processed lactose based powders intended for direct compression. Lactose possesses unacceptable powder flow properties and this is one of the reasons why co-processed powders were developed. One of the great advantages of lactose is that it is water soluble, therefore, not influencing the solubility of the active ingredient incorporated in the tablet.
To determine the efficacy of the different binders (Kollidon® 30, VA64 and 90F), wet granulation was used to prepare granules from lactose. Wet granulation is used to enlarge powder particles, producing bigger agglomerates (granules) with better flow properties (because of the spherical shape) and compressibility to produce solid dosage forms. As binders, Kollidon® 30, VA64 and 90F were employed. The binders were used at three concentration levels (3, 6 and 10% w/w) to produce granules by means of wet granulation. Granules were prepared using ethanol as granulating fluid for Kollidon® 30 and VA64, and distilled water for Kollidon® 90F. Granules from the 10% w/w Kollidon® 90F formulation could not be prepared, as the wet powder mass could not be screened through the sieve. The granules obtained were dried in an oven for a specific time and at a specific temperature depending on the binder in question. A second step of granulation took place and the granules obtained were mixed with the disintegrant (1% w/w Explotab®) and the lubricant (0,5% w/w magnesium stearate). The disintegrant was incorporated in a 50:50 ratio (intra-granular: extra-granular). All the powders were mixed in a Turbula® mixer. The quantity of disintegrant and lubricant was kept constant for all formulations as this was not variables for this study.
During the initial phase of the study the physical properties (flow properties and compressibility) of the powder mixtures produced with the different binders (Kollidon® 30, VA64 and 90F) were evaluated to establish the influence of the binder. All the formulations exhibited acceptable powder flow properties and compressibility.
Tablets were compressed at two compression settings (stroke length 1 and 4) from the different powder mixtures. Two compressions settings were used to determine how the different binders would react under different external pressures. The die volume of the tablet press was kept constant. The physical properties of the obtained tablets were evaluated with respect to tablet weight variation (%RSD), mechanical strength (crushing strength and friability) and disintegration. Tablets produced from Kollidon® 90F powder mixtures exhibited shortcomings in terms of disintegration as it exceeded the disintegration time limit of twenty minutes (in house specification). Results with regard to the mechanical properties of the tablets from all three binders employed, proved that there was no significant benefit by increasing binder concentration.
Kollidon® VA64 proved to be the most favorable binder in terms of disintegration. It was, therefore, selected and a compressible powder containing furosemide was prepared by means of wet granulation. Tablets were manufactured at the same concentration levels as previously mentioned and evaluated with respect to tablet weight variation (%RSD), mechanical strength (crushing strength and friability), disintegration and dissolution. Incorporation of furosemide had no detrimental effect on the weight variation as well as the mechanical strength (crushing strength and friability) of the tablets produced from the different formulations. However, disintegration behavior was negatively affected by the incorporation of the active ingredient. Only the tablets produced from the 3% w/w powder mixtures containing furosemide compressed at compression setting 1, exhibited disintegration below twenty minutes (disintegration time limit). Dissolution of furosemide (model drug representing sparingly water soluble drugs) from tablets produced from different powder mixtures (3, 6 and 10% w/w) of Kollidon® VA64 was determined in 0.1 M HCI for 90 minutes. Dissolution results were compared in terms of initial dissolution rate (DR|) and extent of dissolution (AUC). At compression setting 1, all three formulations (3, 6 and 10% w/w) exhibited similar dissolution profiles. However, dissolution results revealed significant differences in the rate (DR,) and extent (AUC) of furosemide dissolution between the 3% w/w and both the 6 and 10% w/w formulations. Tablets prepared at higher compression levels for both the 6 and 10% w/w concentration level exhibited poor dissolution profiles. The higher compression force caused a decrease in tablet porosity and as a result the disintegration time was prolonged. Water penetrated the tablet matrix to a lesser extent and disintegration was negatively influenced. This, in combination with the hydrophobic nature of furosemide, is the probable cause for the poor dissolution behaviour of the 6 and 10% Kollidon® VA64 formulations at compression setting 4. The dissolution results indicated that disintegration is not an absolute prerequisite for dissolution, as tablets from the 6 and 10% w/w formulations did not disintegrate, but still exhibited dissolution, depending on the compression force. Dissolution results also indicated the dependency of the extent of drug dissolution (AUC) on the initial dissolution rate (DR,), indicating the importance (although not an absolute prerequisite) of establishing rapid contact between drug particles and the surrounding dissolution medium.Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2009.
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Subianto, Surya. "Electrochemical synthesis of melanin-like polyindolequinone." Thesis, Queensland University of Technology, 2006. https://eprints.qut.edu.au/16427/1/Surya_Subianto_Thesis.pdf.
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Conducting polymer is a rapidly developing area of research due to its potential in combining the physical properties of polymers with electrical properties previously found only in inorganic systems. These conducting polymers owe their unique properties to a conjugated polymer backbone and become conducting upon oxidation or reduction.
Melanin, a biopolymer, possess a conjugated backbone required of a conducting polymer, and has shown properties of an amorphous semiconductor. However, there has not been much study done in this area despite its potential, and this is partially due to the lack of processing methods as melanin is generally synthesised as an intractable powder. Thus, a better synthetic method was required, and a possible solution is the use of electrochemical synthesis.
In our previous study we have shown that melanin can be synthesised electrochemically as a free-standing film, which was the first step towards the use of melanin as a bulk material. This project aims to continue from this preliminary work, investigating the various synthetic parameters and possible modifications as well as investigating possible applications for the electrochemically synthesised melanin film.
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Subianto, Surya. "Electrochemical synthesis of melanin-like polyindolequinone." Queensland University of Technology, 2006. http://eprints.qut.edu.au/16427/.
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Conducting polymer is a rapidly developing area of research due to its potential in combining the physical properties of polymers with electrical properties previously found only in inorganic systems. These conducting polymers owe their unique properties to a conjugated polymer backbone and become conducting upon oxidation or reduction. Melanin, a biopolymer, possess a conjugated backbone required of a conducting polymer, and has shown properties of an amorphous semiconductor. However, there has not been much study done in this area despite its potential, and this is partially due to the lack of processing methods as melanin is generally synthesised as an intractable powder. Thus, a better synthetic method was required, and a possible solution is the use of electrochemical synthesis. In our previous study we have shown that melanin can be synthesised electrochemically as a free-standing film, which was the first step towards the use of melanin as a bulk material. This project aims to continue from this preliminary work, investigating the various synthetic parameters and possible modifications as well as investigating possible applications for the electrochemically synthesised melanin film.
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Zhuang, Rong-Chuan. "Synthesis of polymers and oligomers containing fluorinated side groups for the construction of hydrophobic surfaces." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2005. http://nbn-resolving.de/urn:nbn:de:swb:14-1120215670616-23184.
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Oligomers and polymers based on functionalized Rf-amides were successfully synthesized for the fabrication of hydrophobic surfaces with either linear or network structure. Firstly, new functionalized Rf-amides (RfCONH-, Rf is a perfluoroalkyl segment) were developed in most cases by a one step reaction and a simple work-up procedure. The reaction behaviors of synthesized Rf-amides in polyreactions were well understood. New fluorinated oligoester polyols, blocked IPDI's, and end-hydroxyl terminated oligo(urea urethane)s have been synthesized, the detail structures and properties are well understood. These materials could be suitable components of powder coatings. On the other hand, the end-hydroxyl terminated oligo(urea urethane)s could be used as reactive additives in high solid content and water-borne coatings. Hydrophobic smooth surfaces based on linear polymers, poly(urea urethane)s and alternating MI copolymers, containing fluorinated side groups were successfully constructed. The attachment of fluorinated side groups into polymers can dramatically alter the surfaces of corresponding polymers from more hydrophilic to hydrophobic due to the enrichment of fluorinated side groups on the top of the surface. The backbone configuration, the polarity of backbones, and the thermal treatment on surfaces can influence the surface properties of corresponding materials. Finally, hydrophobic surfaces of cross-linked polyurethanes as model top coatings were constructed under melt condition at high temperature (180 and 190 oC) using the combination of fluorinated oligouretdiones and non-fluorinated oligoester polyols. It was found that the hydrophobicity of resulting cured films is a matter of the competition between the formation of cross-linking network and the segregation of fluoromoieties on the top of the surface.
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Common, Audrey. "Développement d'un procédé propre assisté par CO2 supercritique pour la production de particules de polyamide : caractérisation et faisabilité." Thesis, Toulouse, INPT, 2011. http://www.theses.fr/2011INPT0113/document.
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Cette thèse vise à la production de poudre de polymère par un procédé continu, en une seule étape et supprimant l'utilisation des solvants organiques en faveur de celle du CO2 supercritique. Avant de développer le procédé, une caractérisation du mélange CO2/polymère a été effectuée. Des mesures de solubilité, de gonflement et de coefficient de diffusion du CO2 ont été réalisées et représentées par différents modèles. De plus, une technique de rhéologie capillaire en ligne a été développée, permettant la mesure de viscosité du polymère, seul ou en mélange, avec le CO2 dans les conditions du procédé. Un montage batch a ensuite permis de tester l'influence des paramètres opératoires sur de faibles quantités. Parallèlement, le procédé continu a été étudié sur une extrudeuse équipée d'outils de mélange du CO2 dans le polymère fondu. L'efficacité et l'homogénéité du mélange ont été étudiées à travers la fabrication de mousses de polymères et la réalisation de distributions de temps de séjour par spectroscopie Raman en ligne. L'ajout d'un dispositif de pulvérisation spécifique a conduit à l'obtention de poudres d'aspect fibreux avec deux populations de taillesPolymer powders are widely used in industry and are traditionally manufactured by processes using organic solvent or by grinding low molecular weight polymers with a post-polymerization step. This thesis aimss at the generation of polymer powders with a single-step continuous process, based on the use of supercritical CO2, hence without organic solvent. Before developing this process, the characterization of the mixture CO2/polymer was done. Solubility measurements were carried out and fitted with the Sanchez-Lacombe equation of state. Moreover, a capillary rheometry technique was implemented on-line, allowing the measurement of the viscosity of the polymer alone or in mixture with CO2, under process conditions. The modeling of swelling as a function of time led to the evaluation of the diffusion coefficient of CO2 into the polymer. Afterwards, two experimental devices were designed. A batch process with a pressurized autoclave was used to determine the influence of experimental parameters on powder production, with small amounts of material. Formation of small fibrous particles was obtained. In parallel, the continuous process was studied on an extruder adapted to CO2 introduction and equipped with mixing devices. This study, which led to foam manufacture, was used to evaluate efficiency and homogeneity of the mixing. Residence time distributions were determined by Raman spectroscopy on the die in order to evaluate the flowing in the extruder under different conditions. The equipment was also fitted with a specific nozzle allowing co-injection of hot air. Production of fibrous particles with two different size ranges was obtained
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Machado, Jaison Carlosso. "Desenvolvimento e controle de qualidade de micropartículas poliméricas contendo praziquantel para o tratamento pediátrico da esquistossomose." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2016. http://hdl.handle.net/10183/181180.
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A esquistossomose é uma doença parasitária aguda e crônica causada por vermes sanguíneos (vermes nematoides) do gênero Schistosoma. O homem contrai a esquistossomose através da penetração ativa da cercaria na pele. A importância do tratamento desta enfermidade consiste não só no fato de curar a doença ou diminuir a carga parasitária dos pacientes, bem como impedir sua evolução para formas mais graves. Para o tratamento da esquistossomose o fármaco de escolha é o praziquantel; isso se deve ao seu amplo espectro, sua eficácia, segurança e a relação custo/tratamento. A única forma farmacêutica disponível no Brasil é o comprimido, na dose de 600 mg, a qual pode ser subdividida em quatro partes de 150 mg, a fim de facilitar o ajuste de dose. No entanto, no momento da subdivisão dos comprimidos ocorre o rompimento do revestimento. Este fato acaba levando a uma exposição do fármaco e, consequentemente, de seu sabor amargo. Esta característica dificulta a administração do medicamento, principalmente na população infantil, prejudicando o tratamento e o controle da doença. Uma alternativa para este problema é o desenvolvimento de sistemas poliméricos microparticulados que associados ao fármaco impediriam o contato direto com as papilas gustativas e assim promoveriam uma melhoria na palatabilidade. Para isso utilizou-se a técnica modificada de deposição interfacial do polímero pré-formado seguido de secagem por aspersão. Três matrizes poliméricas, com diferentes características de liberação foram utilizadas, Eudragit RL 100 – liberação tempo dependente e Eudragit E100 e L30D-55 – liberação pH dependente. Além disso, dois tipos de sistemas carreadores do fármaco foram preparados, microcápsulas e microesferas poliméricas. Estes sistemas obtidos foram avaliados e caracterizados a fim de eleger a melhor proposta de formulação visando o mascaramento do sabor do fármaco. De acordo com os resultados obtidos selecionou-se um sistema composto por microcápsulas formadas a partir do polímero L30D-55. A partir de então inseriu-se este sistema na forma farmacêutica pó para suspensão oral, onde diferentes propostas de formulações, contendo dois edulcorantes auxiliares, aspartame e sacarina, separadamente, e seus respectivos placebos foram avaliadas através de um método in vitro para a determinação do sabor, a língua eletrônica ou sensor gustativo. As diferentes formulações avaliadas apresentaram capacidade em mascarar o sabor desagradável do fármaco e, assim resultam em uma promissora alternativa para o aumento da adesão por parte dos pacientes à terapêutica, principalmente para crianças, em virtude da facilidade de administração, do ajuste da dose em função da massa corpórea e ao sabor muito mais agradável ao paladar infantil.Schistosomiasis is a parasitic disease acute and chronic caused by blood worms (nematodes worms) of the genus Schistosoma. Man acquires schistosomiasis through the active penetration of the worms in skin. The importance of treatment of this disease is not only the fact of curing the disease or decreases the parasite load of patients, well as prevent progression to more severe forms. For the treatment of schistosomiasis praziquantel is the drug of choice, this is due to its wide spectrum, its efficacy, safety and the relation cost / treatment. The single dosage form available in Brazil is tablet at a dose of 600 mg, which can be subdivided into four parts of 150 mg to facilitate dose adjustment. However when the subdivision of the tablets occurs the disruption of the coating. This fact provides a drug exposure and consequently of its bitter taste. This characteristic complicates the administration of the drug mainly in children, affecting the treatment and control of disease. An alternative for this problem is the development of microparticulate polymeric systems which associated with the drug would prevent direct contact with the taste buds and thus promote an improvement in palatability. For this was used a modified technique interfacial deposition of preformed polymer followed by spray drying. Three polymer matrices with different release characteristics have been used, Eudragit RL 100 – time dependent release, and Eudragit E100 and L30D-55 – pH dependent release. Furthermore, two types of drug carrier systems have been prepared, polymeric microspheres and microcapsules. These systems obtained were evaluated and characterized in order to select the best proposal formulation aimed at masking the taste of the drug. According to the results we selected a system comprising microcapsules formed from L30D-55 polymer. From then was inserted into this system in the pharmaceutical form, powder for oral suspension, where different proposals formulations containing two auxiliary sweeteners, aspartame and saccharin, separately, and their respective placebos were evaluated in an in vitro method for determining the taste, the electronic tongue. The different formulations tested presented excellent ability to mask the unpleasant taste of the drug and thus present an excellent alternative for increasing adherence to therapy, especially for children, because of the ease of administration, according on dose adjustment of body mass and the much more palatable to children's taste.
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KIYAN, LUDMILA de Y. P. "Aplicação da radiação gama para incorporação do pó de borracha em formulações de borracha EPDM e nitrílica." reponame:Repositório Institucional do IPEN, 2014. http://repositorio.ipen.br:8080/xmlui/handle/123456789/23177.
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Dissertação (Mestrado em Tecnologia Nuclear)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP