Blendas de poli(metacrilato de metila) (PMMA) e polietileno linear de baixa densidade (PELBD)

AUTOR(ES)
DATA DE PUBLICAÇÃO

2001

RESUMO

The aim of this work was to study blends of poly(methyl methacrylate), PMMA, and three kinds of linear low density polyethylene, LLDPE, each having distinct microstructures. Their mechanical or morphological properties were determined in function of composition, processing conditions and route of compatibilization. Blends of PMMA/LLDPE were prepared in a continuos and in a discontinuous mixer, varying composition (10 and 20 % of polyethylene), temperature and shear rate. The compatibilization of the blends was carried out in two ways: in-situ compatibilization and addition of compatibilizer, the graft copolymer PMMA-HDPE, which was prepared in a discontinuous mixer. The morphology of the blends was investigated after processing in both types of mixer and also after injection molding. The mechanical properties were determined by flexural, tensile and impact tests. Blends prepared in the discontinuous mixer showed morphology of spherical domains of LLDPE dispersed in the PMMA matrix, and their sizes varied for each type of polyethylene. After ínjection molding, the blends presented approximately the same domains size for all the different LLDPE, indicating that the microstructure of the polyethylenes have no effect on morphology in equilibrium. Blends obtained from continuous mixer showed a morphology tormed mainly by fibers of LLDPE dispersed in PMMA matrix and oriented towards extrusion direction. This morphology was unstable in injection process, resulting in break-up of the fibers and coagulation. The compatibilization stabilized partially the morphology. Mechanical tests showed that blends containing 10 % of LLDPE and 5 % of the compatibilizer prepared in-situ do not break under flexural stress and nave elongation and impact energy 75 % and 50 % higher than PMMA, respectively.

ASSUNTO(S)

blendas blendas - propriedades mecanicas polietileno

ACESSO AO ARTIGO

Documentos Relacionados