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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.
1

Poliuretanos termopl?sticos : efeito de diferentes processos de s?ntese nas propriedades t?rmicas, mec?nicas e reol?gicas / Thermoplastic polyurethanes : effect of different synthesis methods in thermal, mechanical and rheological properties

Saft, Graziella Kassic 27 March 2017 (has links)
Submitted by Caroline Xavier (caroline.xavier@pucrs.br) on 2017-06-19T17:35:18Z No. of bitstreams: 1 DIS_GRAZIELLA_KASSICK_SAFT_COMPLETO.pdf: 2216882 bytes, checksum: 27b784b828b9a17169149cb562f8c4c7 (MD5) / Made available in DSpace on 2017-06-19T17:35:18Z (GMT). No. of bitstreams: 1 DIS_GRAZIELLA_KASSICK_SAFT_COMPLETO.pdf: 2216882 bytes, checksum: 27b784b828b9a17169149cb562f8c4c7 (MD5) Previous issue date: 2017-03-27 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / Thermoplastic polyurethanes (TPUs) are polymers which can be used widely in many fields, such as shoes industry and engineering parts. They can be produced by two different synthesis methods, known by one step process or two step one. These methods can influence the separation between hard and soft segments and also their morphological, rheologycal, thermal and mechanical properties. This work studied morphological, rheologycal, thermal and mechanical properties of TPUs produced by these different synthesis methods, before and after their thermal treatment (annealing). Two step process was made by batch, although one step process was made by continuous production. Annealing influenced thermal and mechanical properties, increasing cristalinity, thermal stability and mechanical performance, such as abrasion resistance, tensile strenght and tear one. Besides that, it was determined that one step process made a TPU which has lower polydispersity than TPU made by two step one. It was realized that once annealing is applied to a sample obtained by batch process, it was increased its thermal and mechanical performance. / Poliuretanos termopl?sticos (TPUs) s?o pol?meros utilizados amplamente em diversas ?reas, entre elas o mercado cal?adista e de pe?as de engenharia. Podem ser sintetizados a partir de dois diferentes processos de polimeriza??o, conhecidos como processo em uma etapa ou em duas etapas. Esses processos s?o capazes de influenciar o grau de separa??o de segmentos r?gidos e flex?veis do material, bem como as propriedades reol?gicas, t?rmicas e mec?nicas. Este trabalho avaliou as propriedades morfol?gicas, reol?gicas, t?rmicas e mec?nicas de TPUs, produzidos por uma (processo cont?nuo) e duas etapas (processo batelada), com e sem tratamento t?rmico. Como principais resultados, tem-se que o tratamento t?rmico exerceu grande influ?ncia nas propriedades t?rmicas e mec?nicas, como aumento da cristalinidade, da estabilidade t?rmica e da melhora do desempenho mec?nico, como resist?ncia ? abras?o, tra??o e rasgo. Al?m disso, o m?todo de uma etapa levou ? forma??o de um TPU com uma menor polidispersividade na distribui??o de massa molar. A partir das vari?veis analisadas, constatou-se que o m?todo em uma etapa produziu um TPU com melhor separa??o segmentos r?gidos e flex?veis. No entanto, o tratamento t?rmico aplicado ? amostra produzida pelo m?todo de duas etapas levou a uma melhora significativa do desempenho do material, no que se refere ?s propriedades t?rmicas e mec?nicas.

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