Beta phase formation of polypropylene with bentonite filler

In this paper, a study on Polypropylene (PP)/bentonite composites is presented. PP/bentonite composites were prepared using 5%, 10% and 25% of concentration in weight of unmodified and modified bentonite filler. The relative leve! of the beta phase of the samples was calculated using Wide Angle X-ray Diffraction (WAXD). Differential scanning calorimeter (DSC) was used to observe the melting and crystallization behaviour of the samples. The dispersion state of the composites was observed using optical rnicroscopy. The obtained results show the possibility of inducing the beta phase in PP material using bentonite as filler. However, only the composites of polypropylene with modified bentonite showed the beta signa! and higher content was at 10% of filler. Although at 10% of modified bentonite the dispersion is worse than in 5%, at 10% there are more nucleating sites for beta phase formation and consequently more beta content. However, as concentration ofthe filler increases to 25%, the nucleating sites also increase but its dispersion into the compound becomes worse which strongly decreases the beta phase formation.

Mots clés

composites; polypropylene; beta phase; bentonite; treated filler; dispersion state