Nanocompósitos PP/argila. Influência do tipo e do teor de silicato em camadas.

Abstract

Polypropylene (PP) and clay nanocomposites were prepared by the melt intercalation process. Bentonite clay, provided by Bentonit Uniao Nordeste, of Campina Grande, Paraiba (Brazil), was subject to a chemical purification treatment in order to remove organic matter impurities. Raw and purified clays were then modified with the organic salt cetyl trimethyl ammonium bromide. Clays samples were characterized by infrared spectroscopy and x-ray diffraction. Results showed that the purification and organofilization treatments were successful. As a comparative, tests were also performed with a commercial organoclay (Closite 20A) provided by Southern Clay Products, Gonzales, Texas (USA). PP/bentonite nanocomposites with 1, 3 and 5 % organoclay loading (by weight) were prepared in a counter-rotating twin-screw extruder coupled to a Haake rheometer. Test specimens were injection-molded for mechanical and thermal characterization. The composites morphology was evaluated by x-ray diffraction. Hardness, impact, and heat deflection tests were also performed. Then results showed that the type and amount of clay greatly affect the morphology and mechanical properties of the composite. In general, better results were obtained with 1% organofilic clay. Nanocomposites prepared with the bentonite purified and organofilized in this study showed properties similar to those prepared with the commercial organoclay tested.