Preparação de nanocompósitos polipropileno/bentonita: avaliação das propriedades mecânicas e estabilidade térmica.

Abstract

In this work, polypropylene nanocomposites (PP) / bentonite were prepared by the melt intercalation method, employing an extruder coupled to the Haake torque rheometer. Initially, two bentonites, a commercial sodium - Brasgei (BRG) and a partially sodium - Sludge Green (VDL) - were modified with a quaternary ammonium salt aimed at synthesize organophilic clays. These clays were characterized by chemistry, infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermogravimetry (TG). The results of these analyzes showed that the salt was incorporated into the clays, thus obtaining organophilic clays. A study of the best method of incorporating clay into polypropylene. Two methods were studied. One employing direct extrusion of the cold PP / bentonite and another using extrusion of a PP / bentonite concentrate in concentration of 1: 1, which was prepared in an internal mixer (Rheomix 600) coupled to the Haake torque rheometer. This last method contributed to the better dispersion of the clay in PP. It was also evaluated the effect of the processing on the properties of PP / bentonite systems. Two temperatures were studied (210 ° C and 180 ° C). Systems processed at 210 ° C presented better mechanical properties. Thus, PP / bentonite containing BRG (unmodified and modified) sodium bentonite and VDL polycationic bentonite (unmodified and modified), in contents of 1 to 5% by weight, were processed at 210 ° C using the focused. The results obtained showed that the type and content of bentonite had influence on the mechanical and thermal properties of PP. The best bentonite-containing systems and low levels (1-3% by mass). The results also showed that, in a In general, the modification of bentonites had little influence on mechanical properties of PP / bentonite systems. On the other hand, thermal stability was strongly affected. The PP / bentonite systems, containing modified bentonite, thermal stability considerably higher than containing unmodified bentonite. The result was attributed to the formation of nanocomposite as indicated by the XRD data.