Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING / Includes bibliographical references. / by Curtis Harold Stern. / B.S.

Thesis (Mech.E)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / by Audie Y.K. Mak. / Mech.E

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING / Bibliography: leaves 48-50. / by Maura Elizabeth Donnelly. / M.S.

Novel plastic sheets and foams from vegetable oil-based monomers were produced. These new polyurethanes were synthesized from aromatic polyols, with erucic acid as the starting material. These monomers have the unique feature of containing an aromatic ring which was hypothesized to improve the rigidity of the polyurethane matrices and the overall physical properties of the plastics and foams. The benefits of the aromatic ring were proposed to be enhanced due to three terminal primary hydroxyl groups within the structure of the polyols. Reactions to produce hexasubstituted benzene derivatives containing alcohol groups in positions 1,2,4- and 1,3,5- around the benzene ring were suitably scaled up to provide amounts necessary for polyurethane production and characterization. These isomers (asymmetric and symmetric triols) were separated using chromatography. The pure triols were crosslinked with 4,4-methylenebis(phenyl isocyanate) into polyurethanes sheets (asymmetric and symmetric polyurethane respectively). The physico-chemical properties of these PUs were studied by Fourier transform infrared spectroscopy, x-ray diffraction,, differential scanning calorimetry dynamic mechanical analysis, thermogravimetric analysis coupled with Fourier transform infrared spectroscopy, and tensile analysis. The asymmetric polyurethane sheet and the symmetric polyurethane sheet differed in their glass transition temperatures and crosslinking densities. This variation could be explained by the differences in crosslinking densities, related to the increase in steric hindrance between adjacent hydroxyl groups of the asymmetric triol monomers. It was found that both polyurethanes had similar mechanical and thermal properties. Due to the similar properties of the asymmetric polyurethane and symmetric polyurethane sheets, the monomers were combined together in order to synthesize PU foams. The physical properties of these foams were studied by Fourier transform infrared spectroscopy, differential scanning calorimetry, dynamic mechanical analysis, scanning electron microscopy, thermogravimetric analysis and were analyzed for close cell content and compression strength. The effect of the benzene ring in the monomer structure on the physical properties of these new polyurethane foams was mainly compared with high density canola polyurethane foams previously investigated. It was demonstrated that the physical properties of polyurethane foams made with aromatic monomers are comparable to those made with aliphatic monomers when enhanced with glycerol. / Bioresource and Food Engineering

No description available.

Thesis (Ph. D.)--University of Washington, 2004. / Vita. Includes bibliographical references (leaves 275-317).

Thesis (M.S.)--Texas State University--San Marcos, 2008. / Vita. Includes bibliographical references (leaves 82-84). Also available on microfilm.

Neste trabalho foram obtidos nanocompósitos contendo 0, 1, 2, 5 e 10% (m/m) de argila organofílica montmorilonita cloisite 30B, contendo terminações hidroxila, por processamento reativo entre um pré-polímero com terminações isocianato e o 1,4-butanodiol, utilizando-se um misturador fechado. Os resultados mostraram que os poliuretanos termoplásticos sintetizados foram obtidos com sucesso. A adição de montmorilonita nos TPUs ocasionou a formação de folhas de argila dispersas de maneira intercalada, parcialmente esfoliada, esfoliada e aglomerados na matriz do TPU. Com a adição da argila houve modificações nos comportamentos de cristalização, estabilidade térmcica e mecanismo de degradação, assim como um aumento nos valores de energia aparente de ativação deste processo. A mobilidade de alguns segmentos poliméricos também foi alterada com a adição da argila. Portanto modificações morfológicas e viscoelásticas foram observadas para os nanocompósitos em dependência da quantidade de argila organofílica empregada, assim como a adição da organoargila alterou o comportamento térmico do poliuretano termoplástico, tornando os nanocompósitos mais suscetíveis a mudanças nos processos de fusão e cristalização em função da exposição a temperaturas elevadas. / In this study, were obtained nanocomposites containing 0, 1, 2, 5 and 10% (w/w) of organophilic clay montmorillonite Cloisite 30B, containing hydroxyl terminations, by reactive processing between a prepolymer with isocyanate terminations and 1,4-butanediol, using a closed mixer. The analysis showed that the obtained thermoplastic polyurethanes were synthesized successfully. The addition of the montmorillonite in the TPUs resulted in the formation of sheets of clay dispersed in order intercalated, partially exfoliated, exfoliated and agglomerate in the TPU matrix. With the addition of clay there were changes in the behavior of crystallization, thermal stability and degradation mechanism, as well as an increase in the values of the apparent activation energy of this process. The mobility of certain polymer segments was also changed with the addition of the clay. Therefore viscoelastic and morphological changes were observed in the nanocomposites in dependence on the amount of organophilic clay used, as well as the addition of the organophilic decreased the thermal stability of the thermoplastic polyurethane, making nanocomposites more susceptible to changes in the melting and crystallization processes due to exposure to elevated temperatures.

Submitted by Milena Rubi (milenarubi@ufscar.br) on 2016-11-17T18:09:38Z No. of bitstreams: 1 OLIVEIRA_Elisangela_2015.pdf: 17350237 bytes, checksum: a1efb77501c4df3e09734ffce33e70c1 (MD5) / Approved for entry into archive by Milena Rubi (milenarubi@ufscar.br) on 2016-11-17T18:09:47Z (GMT) No. of bitstreams: 1 OLIVEIRA_Elisangela_2015.pdf: 17350237 bytes, checksum: a1efb77501c4df3e09734ffce33e70c1 (MD5) / Approved for entry into archive by Milena Rubi (milenarubi@ufscar.br) on 2016-11-17T18:09:55Z (GMT) No. of bitstreams: 1 OLIVEIRA_Elisangela_2015.pdf: 17350237 bytes, checksum: a1efb77501c4df3e09734ffce33e70c1 (MD5) / Made available in DSpace on 2016-11-17T18:10:11Z (GMT). No. of bitstreams: 1 OLIVEIRA_Elisangela_2015.pdf: 17350237 bytes, checksum: a1efb77501c4df3e09734ffce33e70c1 (MD5) Previous issue date: 2015-03-19 / Não recebi financiamento / One of the most remarkable and diverse physical characteristics among human beings - and, thus, fundamental for personal identity - is hair. The search for personal hair care products has been increasing in the last years and Brazil is the third largest consumer market for these products. There is a constant quest for cosmetic products able to align, relax and treat hair fibers. There are some products for this purpose, such as smart brushes, Japanese brushes and definitive brushes, among others. In this context, the aim of this project was to synthesize and characterize polyurethane obtained from a renewable source as well as evaluate its effectiveness as a hair treatment agent. Therefore, scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier-transform infrared spectroscopy (FTIR), nearinfrared reflectance spectroscopy (NIRS) and mechanical tests for tensile properties were used. The FTIR results confirmed the synthesis of the polyurethane. The polymer was associated with citric acid, glycolic acid, lactic acid, and sodium hydroxide with glycose, in order to increase adhesion of the polymer onto the hair fiber. After application, better hair fiber alignment and increased hair roughness were noticed. Through the spectroscopic analysis it was established that a chemical interaction between the polymer, its associations and hair was present. The micrographs also suggested that there was a deposition of the polymer on the hair fibers. The results indicated that the polyurethane and their associations with citric acid and sodium hydroxide with glycose, are promising for applications in hair care products. / Os cabelos constituem uma das características físicas mais marcante e variável dos seres humanos, tornando-se fundamental para a identidade pessoal. Assim, é cada vez maior a busca por produtos para os cuidados dos mesmos. O Brasil é o terceiro maior mercado consumidor de produtos para os cabelos, e existe uma busca constante pelas empresas do setor de cosméticos por produtos capazes de alinhar, relaxar e tratar os fios. Neste sentido podemos encontrar produtos para essa finalidade, com as mais variadas denominações, como as escovas: inteligente, japonesa, definitiva entre outras. Dentro desse contexto, o objetivo do presente projeto foi sintetizar e caracterizar um poliuretano a partir de um poliol obtido de fonte renovável, e avaliar sua eficácia após aplicação do mesmo visando tratamento capilar. Para tanto, foram utilizadas técnicas de microscopia eletrônica de varredura (MEV), microscopia de força atômica (AFM), espectroscopias de infravermelho por transformada de Fourier (FTIR) e espetroscopia de refletância no infravermelho próximo (NIRS) e ensaios mecânicos pelo módulo de tração. Os resultados de FTIR confirmaram a síntese do poliuretano, o qual foi associado aos Ácidos Cítrico, Glicólico, Lático e Hidróxido de Sódio com Glicose com o intuito de aumentar a aderência do polímero na fibra capilar. Após a aplicação verificou-se um melhor alinhamento dos fios e aumento na rugosidade. Através das análises de espectroscopia foi possível constatar que houve uma interação química entre o polímero, suas associações e os cabelos. As eletromicrografias também sugerem que houve uma deposição do polímero sobre as fibras do cabelo. Os resultados obtidos indicaram que o poliuretano e suas associações com ácido cítrico e hidróxido de sódio e com glicose, são promissores para aplicações em produtos capilares.

Nessa dissertação foi estudada a síntese de elastômeros microcelulares de poliuretano (EMPU). Foram preparados três EMPU baseados em diisocianato de 4,4 difenilmetano (MDI), com diferentes concentrações de fase rígida (Formulações 1, 2 e 3, com 32, 35 e 42% de fase rígida, respectivamente). As amostras foram preparadas através do método de duas etapas, pelo sistema de pré-polímero. As amostras dos EMPU foram caracterizadas através de ensaios físicos, mecânicos, morfológicos, térmicos e químicos. Os resultados dos ensaios mecânicos mostraram que o aumento no percentual de fase rígida levou a um aumento na resistência à tração e na resistência ao rasgamento. O alongamento na ruptura não apresentou variação significativa com a modificação do percentual de fase rígida. As análises morfológicas indicaram que o aumento no percentual de fase rígida promoveu a formação de microcélulas menores, distribuídas de forma mais homogênea no elastômero. As análises de termogravimetria indicaram a presença de dois estágios de degradação, referentes às fases rígida e flexível, respectivamente. Os ensaios de calorimetria exploratória diferencial indicaram que os EMPU apresentam uma separação de fases à temperatura ambiente. O aumento na quantidade de fase rígida presente nos EMPU implicou em maiores valores de densidade de ligações cruzadas. O ensaio de resistência química demonstrou que os EMPU formulados apresentaram baixos índices de inchamento para solventes industriais comumente utilizados. / Submitted by Marcelo Teixeira (mvteixeira@ucs.br) on 2014-05-13T17:30:17Z No. of bitstreams: 1 Dissertacao Marcos F M Pacheco.pdf: 1713515 bytes, checksum: 5a2d6fb47ee26d6b8f32b744d387c8ce (MD5) / Made available in DSpace on 2014-05-13T17:30:17Z (GMT). No. of bitstreams: 1 Dissertacao Marcos F M Pacheco.pdf: 1713515 bytes, checksum: 5a2d6fb47ee26d6b8f32b744d387c8ce (MD5) / In this work, three different microcellular polyurethanes elastomers (EMPU) based on 4,4-diphenylmethane diisocyanate (MDI) with different rigid phase contents were prepared (Formulations 1, 2 and 3 with 32, 35 and 42% of rigid phase content, respectively). The EMPU were obtained by two steps method. The samples were evaluated with respect to physical, mechanical, morphological, thermal and chemical properties. The results showed that the formulation with higher rigid phase content has higher tensile and tear strength. The deformation at rupture not show significant variation with the change in the rigid phase content. Micrographs of SEM indicated that the higher rigid phase content promoted the best cells homogeneity in the samples. The termogravimetric analysis show the presence of the two degradation steps associated to the rigid and flexible phase, respectively. Diferential scanning calorimetry indicated that the EMPU has a phase separation at room temperature. The increase in the rigid phase content implicated in the increase of the cross-linked density of the material. Finally, the EMPU have good chemical resistence in comumm solvents.