Affiliation:
1. Grupo de Catálisis y Procesos de Separación (CyPS), Departamento de Ingeniería Química, Facultad de C. Químicas, Universidad Complutense de Madrid, Madrid, Spain
Abstract
This paper analyses the thermal behaviour of six EVA copolymers supplied by REPSOL Company. In relation to crystallization and melting temperatures, both of them decrease when the vinyl acetate percentage increases, in agreement with the fact that polyethylene is a semi-crystalline material, whereas polyvinylacetate is an amorphous polymer. Actually, when the vinyl acetate percentage reaches 30%, the copolymer is practically amorphous. The non-isothermal crystallization was modelled with the modified Avrami model that showed, with the exception of EVA-460 (the material with higher vinyl acetate percentage), the presence of a secondary crystallization due to spherulite impingement in the later stage of the non-isothermal crystallization. The TG analysis indicated two weight loss stages, the first one due to acetic acid loss and the second one due to fragments of polymer backbone, which appear as two separate peaks in the DTG plots. Finally, due to the linear dependence of melting and crystallization temperatures and of the minimum value of DTG peaks on vinyl acetate percentage, it can be concluded that both TG and DSC techniques can be employed to determine the vinyl acetate percentage of a certain copolymer.
Subject
Materials Chemistry,Polymers and Plastics
Cited by
10 articles.
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