Mechanical properties and crack propagation of soy‐polypropylene composites

Abstract

Abstract Composites from soy flour (SF) and polypropylene (PP) exhibited increased impact and flexural properties when SF was treated with potassium permanganate (KMnO 4 ) or when subjected to autoclave treatment and maleic anhydride coupling agent addition. The impact strength increased by at least 13% for the KMnO 4 SF composites and by 18% for the autoclave SF composites with maleic anhydride coupling agent addition. These two SF composite materials showed increased impact and flexural modulus, an indication of multiscale material architecture. Scanning electron microscopy imaging of the fractured surfaces revealed different morphology and potential crack propagation mechanisms. Composites with untreated SF showed poor bonding with the polypropylene matrix whereas improved bonding was observed for SF subjected to KMnO 4 treatment. Composites with SF subjected to autoclave treatment combined with maleic anhydride revealed good bonding. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013