Efeito do tipo de polipropileno e das condições de processamento na formação e propriedades de compósitos com argila organofílica.

Abstract

Composites of homopolymer polypropylene and random and heterophasic copolymers of 5% by weight of commercial organophilic clay, maleic anhydride grafted polypropylene as compatibilizing agent in contents of 5 and 15%, and erucamide as co-intercalating agent were prepared. 0.5 and 1.0% by means of the merged process in the molten state, employing different equipment and processing conditions. The composites were processed in an internal mixer and double screw extruder with two different profiles and at different speeds, and then characterized by mechanical properties, morphology and flammability test. The X-ray diffraction results indicated that the polymeric matrix type affects the dispersion of clay in the system, and the formation of intercalated structures was observed, especially when the co-intercalating agent was employed. Transmission electron microscopy showed the incipient exfoliation of organophilic clay. The mechanical behavior of the obtained composites was superior to that of the polymeric matrix, except for the impact resistance, which showed reductions, especially the composites based on heterophasic copolymer. Reprocessing cycles did not significantly affect the mechanical properties of the composites. The flammability test indicated increase of the burning rate and the formation of a carbonaceous layer avoiding dripping of the sample. Variations of the processing method indicated that the clay undergoes the expansion process of its lamellae due to the presence of compatibilizer and co-intercalant mainly during the preparation of concentrates in the mixer and the simulation of the twin screw extruder with commercial software satisfactorily correlated the results. experimental.