Estudo reológico em regimes permanente e oscilatório de nanocompósitos com matriz de polipropileno.

Abstract

In this work polypropylene (PP)/organophilic bentonitic clay (OMMT) and PP/compatibilizer/OMMT nanocomposites were studied. The nanocomposites were prepared using polypropylene as matrix and organophilic bentonite clay as the dispersed phase (0.5, 1, 3, 5 and 10) phr of Brasgel clay was used for preparing the systems. Initially, the clay was organophilizated with the ionic surfactant Praepagen WB® and then characterized by XRD and FTIR techniques. Subsequently, the clay was incorporated into the polymer matrix in order to obtain a nanocomposite with and without compatibilizers. PPgMA and EG were used as compatibilizers. For each type of compatibilizer, the clay concentrations used were 0.5 and 1 phr. The organophilization of clay was confirmed by FTIR and XRD techniques. The formation of the nanocomposites and their characteristics were checked by XRD technique and Theological properties. Through the XRD results it was observed that the behavior of the nanocomposite was the same as the OMMT clay. The clay peaks intensity increased with the increase in the clay content. As for the nanocomposites with PPgMA the peaks were similar to that of OMMT clay. For the EG no OMMT characteristic peak was observed. Rheologically it was observed that the viscosity increased with the clay content and with the compatibilizer type. This variation was seen at low frequencies, both in the steady state, as in the oscillatory regime. The storage modulus at low frequencies was higher compared to pure PP for all compositions investigated. The EG provided more significant changes compared with the PPgMA. Based on these results, we concluded that there was formation of three types of structures: microcomposite; intercalated, and exfoliated and / or intercalated with high degree of dispersion.