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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Vliv rýžového extraktu na lisovatelnost a mechanické vlastnosti tablet z mikrokrystalické celulosy. / The effect of rice extract on the compressibility and mechanical properties of microcrystalline cellulose tablets.

Rumlerová, Lenka January 2019 (has links)
Charles University, Faculty of Pharmacy in Hradec Králové Department of: Department of Pharmaceutical Technology Consultant: PharmDr. Pavel Ondrejček, Ph.D Student: Lenka Rumlerová Title of Thesis: The effect of rice extract on the compressibility and mechanical properties of microcrystalline cellulose tablets. This thesis deals with influence of rice extract, as a new kind of glidant on compressibility of microcrystalline celulose as a model filler. Furthermore it evaluates the impact of rice extract on tablet properties. Effects of rice extract were compared with two standard glidants - magnesium stearate and colloidal silicon dioxide. As first the influence of diferent glidants concetrations on flow properties of mixtures were assesed. Tablets were compresed using three different compression forces. A force- displacement record was used to evaluate the compressibility of microcrystalline cellulose and its mixtures with glidants. Subsequently, the properties of tablets were evaluated. The radial strenght, abrasion, and tablet disintegration time were measured. The results revealed that the rice extract has the least effect on mixtures flow poperties. However, all mixtures showed a statistically significant improvement in flowability. When using a 1 % rice extract, the flow properties of the...
22

Avaliação do emprego de filito como carga em plastisol. / Evaluation of the use of phyllite as filler in plastisol.

Ribeiro, Alcidio Pinheiro 17 January 2003 (has links)
Apresenta-se aqui a caracterização do filito e a avaliação da sua aplicação como carga mineral na produção de materiais plásticos. Amostras de jazidas em lavra no município de Itapeva, sudoeste do Estado de São Paulo, foram preparadas em laboratório, através de secagem e peneiramento, e analisadas física e quimicamente, sendo comparadas com outros minérios utilizados comumente como cargas minerais. Uma dessas amostras, após sua preparação, foi aplicada como carga na produção de peças plásticas no Centro Técnico de Serviços CTS da empresa Braskem S.A., a partir de pastas formadas com PVC e plastificantes, conhecidas como plastisóis. O filito foi incorporado em varias formulações de compostos utilizados para produção de bolas plásticas comuns. Os resultados, em termos de resistência mecânica, foram comparados com os de compostos contendo carbonato de cálcio natural, moído, em malha inferior a 44 m. O carbonato de cálcio natural, ou calcita, constitui a carga mais tradicionalmente utilizada nesse setor industrial. Os testes realizados indicaram que o filito confere ao material polimérico produzido, composto de polímeros, aditivos e cargas, propriedades desejáveis de resistência mecânica e acabamento, algumas propriedades resultando melhores que as obtidas com o uso da calcita para determinadas proporções e formulações. Os resultados obtidos permitem concluir que o filito beneficiado comporta-se similarmente a minerais industriais tradicionais e pode vir a ser empregado na indústria de plásticos dito reforçados na geração de produtos diversos tais como bolas de parque, cabeças de bonecas, tapetes, tubos plásticos flexíveis e painéis de veículos, entre outros segmentos do setor. / This paper presents the characterization of the White-phyllite and an evaluation of its application as filler in the production of plastic materials. Phyllite samples with origin in ore body located in the district of Itapeva, southwest area of Sao Paulo State, they were beneficiated, prepared in laboratory through granulometric separation and drying and applied in the production of reinforced thermoplastic (Plastisol) in laboratories of the Braskem S. A. located in São Paulo city. The accomplished tests indicated that the beneficiated phyllite checks to the material plastic produced desirable properties of mechanical resistance and finish. The use of the phyllite it was compared with the calcite in the production of the plastics materials in several composition and proportions, showing in some compositions strips better than obtained results them with the calcite, traditional filler used for those products. The obtained results allow to conclude that the phyllite, properly beneficiated, is similar to traditional industrial minerals and it can benefit the industry of plastics reinforced in the production, among others, of balls, doll heads, rubber rugs, flexible plastic tubes, panels of vehicles.
23

Fine particulate filled polymeric material and the investigation of its friction and wear properties

Su, Kwai-Yung Benjamin January 1980 (has links)
Thesis (Sc.D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Vita. / Includes bibliographical references. / by Kwai-Yung Benjamin Su. / Sc.D.
24

Estudo clínico e histopatologico da aplicação do polimetilmetacrilato (PMMA) em ratos

Jesus, Luciano Henrique de January 2011 (has links)
Objetivo: O objetivo deste estudo foi avaliar clínica e hitologicamente a reação do material de preenchimento em dois sítios diferentes. Método: Vinte e duas femêas de ratos Wistar (Rattus novergicus) foram submetidas a aplicação de PMMA testando duas técnicas: subcutânea e transmuscular. Passados 3 meses do ato cirúrgico os ratos foram eutanasiados e as áreas injetadas foram excisadas, submetidas a técnica de inclusão em parafina e coloração por hematoxilina e eosina. As lâminas foram analisadas observando-se a resposta local à injeção do corpo estranho quanto ao grau de inflamação. Resultados: Foi encontrada diferença significativamente estatística entre os sítios muscular e subdérmico quanto a formação de granuloma (p<0,05), sendo que o grupo subdérmico obteve melhores resultados. Conclusão: A aplicação de materiais de preenchimento, que provoca maior trauma e sangramento nos tecidos, é a casusa de reações adversas. / Objective: The objective of this study was to evaluate clinical and hitopathology the reaction of the fill material at two different sites. Method: Twenty-two female Wistar rats (Rattus norvegicus) submitted the application of PMMA testing two techniques: subcutaneous and trans. After 3 months of surgery, the rats were euthanized and the injected areas were excised, subjected to paraffin embedding technique and stained with hematoxylin and eosin. The slides were analyzed by observing the local response to injection of foreign body in the degree of inflammation. Results: We found statistically significant differences between sites and subdermal muscle as granuloma formation (p <0.05), and the subdermal group achieved better results. Conclusion: The application of filling materials, which causes more injury and bleeding in the tissues, is Casusa of adverse reactions.
25

Mechanical Behaviour, Water Absorption and Morphology of Wheat Straw, Talc, Mica and Wollastonite filled Polypropylene Composites

Mohan Sharma, Arathi January 2012 (has links)
Polypropylene continues to be the mainstream choice thermoplastic for automotive applications. In many applications PP is filled with mineral fillers for improvement of properties. Biobased natural fillers or fibres are attractive materials to reduce the weight because of the low specific gravity of the biobased materials compared to the mineral fillers. Our group has done extensive research on the development of wheat straw fiber in thermoplastics in the past years. It is very important to understand the behaviour of single fillers on composites before studying the effects of mixing fillers or fibers (hybridization). The objective of this study is to evaluate and compare systematically the effects of wheat straw and mineral fillers in the polypropylene matrix. The study includes two types of wheat straw (WS) categorized based on their size (fine WS and medium WS) and three different types of natural minerals (Talc, Mica and Wollastonite). Three types of polypropylene (PP), Homopolymer PP, High Impact Copolymer PP and Homopolymer-Copolymer Blend PP, were investigated as the matrix. This study also evaluates the effect of combining two fillers (WS and mineral filler) in the hybrid composite. The fillers were formulated in three different percentages (20, 30 and 40wt %) and compounded via extrusion. Samples for all formulations were prepared by injection molding. The mechanical properties (flexural modulus and strength, tensile modulus and strength, impact strength), water absorption and density were measured. The properties of hybrid composites were evaluated by varying the amounts of two fillers at 10wt%-20wt%, 15wt%-15wt% and 20wt%-10wt% each, keeping the overall filler content constant at 30wt%. The effect of type of filler, filler size and filler content were critical in this work. The results obtained from this study indicated that filler type and filler content greatly influenced the mechanical properties and water absorption characteristics of the composites. The flexural modulus increased with increasing filler content. It was interesting to observe that though the impact strength decreased with the addition of fillers, increasing the filler content from 20 to 40 wt% did not affect the property. With respect to all fillers, wollastonite improved the mechanical properties significantly. Increasing the amount of WS content reduced the composite’s resistance to water absorption. Among mineral fillers, mica showed significantly higher percentage gain in weight with water absorption. Combination of fillers at varying percentages did not have any synergy effect on the mechanical behaviour of the composite. The percentage increase in weight with water absorption was observed to be increasing with increasing WS content in hybrid composites, but significantly lower than pure WS composites. The morphological study on WS composites revealed improved interaction of filler with homopolymer and polypropylene blend.
26

A New Approach To Bituminous Composites

Okus, Dilek 01 July 2010 (has links) (PDF)
The healing effects of fillers on bitumen have been known for many years. In this study, the effects of fillers, e.g. manganese dioxide, barium sulfate, perlite and vermiculite, and filler concentrations on morphological, mechanical, flow and sound insulation characteristics of bitumen were examined. It was also aimed to improve the mechanical and sound insulation properties of bituminous composites. Bituminous composites were prepared by using Brabender Plasti-Corder. Mixing was made at 130&deg / C with 60 rpm for 20 minutes. 20/30 and 50/70 penetration grades bitumen, SBS polymer and CaO used in the composites were kept constant. While the amount of CaCO3 was decreased, other fillers (i.e., MnO2, BaSO4, perlite and vermiculite) were added in the same proportion to investigate their effects. According to the test results, all fillers were covered by bitumen as observed in SEM figures. MnO2 composites did not give good results in the tests and they were very brittle. While perlite seemed to have good mechanical properties, it was too viscous to be processed easily. Increase in the amount of vermiculite in the composite caused adverse effects on the rheological properties of composites. However, vermiculite composites provided a remarkable sound insulation in terms of the sound damping ratios. BaSO4 composites gave the best results in the mechanical, flow and sound insulation tests.
27

Nanoreinforced shape memory polyurethane

Richardson, Tara Beth. Auad, Maria Lujan. Schwartz, Peter. January 2009 (has links)
Dissertation (Ph.D.)--Auburn University, 2009. / Abstract. Includes bibliographic references.
28

Mechanical Behaviour, Water Absorption and Morphology of Wheat Straw, Talc, Mica and Wollastonite filled Polypropylene Composites

Mohan Sharma, Arathi January 2012 (has links)
Polypropylene continues to be the mainstream choice thermoplastic for automotive applications. In many applications PP is filled with mineral fillers for improvement of properties. Biobased natural fillers or fibres are attractive materials to reduce the weight because of the low specific gravity of the biobased materials compared to the mineral fillers. Our group has done extensive research on the development of wheat straw fiber in thermoplastics in the past years. It is very important to understand the behaviour of single fillers on composites before studying the effects of mixing fillers or fibers (hybridization). The objective of this study is to evaluate and compare systematically the effects of wheat straw and mineral fillers in the polypropylene matrix. The study includes two types of wheat straw (WS) categorized based on their size (fine WS and medium WS) and three different types of natural minerals (Talc, Mica and Wollastonite). Three types of polypropylene (PP), Homopolymer PP, High Impact Copolymer PP and Homopolymer-Copolymer Blend PP, were investigated as the matrix. This study also evaluates the effect of combining two fillers (WS and mineral filler) in the hybrid composite. The fillers were formulated in three different percentages (20, 30 and 40wt %) and compounded via extrusion. Samples for all formulations were prepared by injection molding. The mechanical properties (flexural modulus and strength, tensile modulus and strength, impact strength), water absorption and density were measured. The properties of hybrid composites were evaluated by varying the amounts of two fillers at 10wt%-20wt%, 15wt%-15wt% and 20wt%-10wt% each, keeping the overall filler content constant at 30wt%. The effect of type of filler, filler size and filler content were critical in this work. The results obtained from this study indicated that filler type and filler content greatly influenced the mechanical properties and water absorption characteristics of the composites. The flexural modulus increased with increasing filler content. It was interesting to observe that though the impact strength decreased with the addition of fillers, increasing the filler content from 20 to 40 wt% did not affect the property. With respect to all fillers, wollastonite improved the mechanical properties significantly. Increasing the amount of WS content reduced the composite’s resistance to water absorption. Among mineral fillers, mica showed significantly higher percentage gain in weight with water absorption. Combination of fillers at varying percentages did not have any synergy effect on the mechanical behaviour of the composite. The percentage increase in weight with water absorption was observed to be increasing with increasing WS content in hybrid composites, but significantly lower than pure WS composites. The morphological study on WS composites revealed improved interaction of filler with homopolymer and polypropylene blend.
29

Characterization and prediction of material response of micro and nano-underfills for flip chip devices

Islam, Muhammad Saiful, Lall, Pradeep. Suhling, J. C. January 2006 (has links) (PDF)
Dissertation (Ph.D.)--Auburn University, 2006. / Abstract. Vita. Includes bibliographic references.
30

Avaliação das propriedades morfo-fisicoquimica e biológica de diferentes acidos hialurônicos (ahs). Estudo in vivo e in vitro /

Oliveira, Morgana Regina Mendonça de. January 2017 (has links)
Orientador: Hermes Pretel / Resumo: O objetivo desse estudo foi realizar a caracterização morfo-fisicoquimica e avaliar a resposta histopatológica e a biodegradação de AH indicados para preenchimento dérmico: DMC-Facial 12,5% (D12) e RennovaFill (RF) e aumento volumétrico de tecido: DMC-Facial 15% (D15) e RennovaLift (RL). A caracterização foi realizada por microscopia eletrônica de varredura (MEV), espéctroscopia dispersiva de raios X (EDX) e infra vermelha com transformada de Fourier (FT-IR) e reometria dinâmica oscilatória. Para avaliação da resposta histopatológica e da biodegradação foi implantado 0,1 mL de cada AH no plano sub-dérmico do dorso de 25 ratos Hostsman, aleatóriamente distribuidos em 5 grupos (n=5), de acordo com o tempo de implantação dos AH (7, 14, 30, 60 e 120 dias). Um examinador experiente (HP), calibrado e cego para os AHs utilizados analisou os cortes. Modelo loglinear e teste de quiquadrado (χ2) foram utilizados para avaliar a associação entre os AH e a intensidade da resposta histopatológica e biodegradação para p<0,05. A hipótese nula (H0) foi rejeitada pois tanto na caracterização morfo-fisicoquimica quanto na avaliação da resposta histopatológica e da biodegradação mostraram diferenças signficatica entre os Ahs testados. Pode-se concluir que: 1) AH com a mesma indicação clínica diferem tanto nas características morfo-fisicoquimica com na resposta inflamatória provocada e no padrão de biodegradação. 2) O nível de resposta histopatológica depende do AH utilizado. 3) Uma morfologia es... (Resumo completo, clicar acesso eletrônico abaixo) / The aim of this study was to perform the morpho-physicochemical characterization and to evaluate the histopathological response and biodegradation of AH indicated for dermal filling: DMC-Facial 12.5% (D12) and RennovaFill (RF) and tissue lifting: DMC-Facial 15% (D15) and RennovaLift (RL). The characterization was performed by scanning electron microscopy (SEM), X-ray dispersive (EDX) and Fourier transform infra red spectroscopy (FT-IR) and oscillatory dynamic rheometry. To evaluate the histopathological response and biodegradation, 0.1 mL of each HA was implanted in the dorsal subdermal plane of 25 male Hostsman rats, randomly distributed in 5 groups (n = 5), according to the time of implantation of AH: 7, 14, 30, 60 and 120 days). Slides were analyzed by a experienced examiner (HP), calibrated and blinded for the AH used. Loglinear model and chi-square statistical test (χ2) were used to evaluate the association between AH and the intensity of histopathological response and biodegradation for p <0.05. Results: The null hypothesis (H0) was rejected because both the morpho-physicochemically characterization and the histopathological analysis showed significant differences between the tested AHs. It can be concluded that: 1) AH with the same clinical indication differ in the morpho-physicochemical characteristics, in the inflammatory response and in the biodegradation pattern. 2) The level of histopathological response depends on the AH used. 3) A structural morphology characteristic of D12 and D15, formed by chambers separated by thin septa, with sharp and irregular borders, causes a greater inflammatory response, 4) All HA tested stimulated the fibroblast and collagen neoformation. 5)...(Complete abstract electronic access below) / Mestre

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