The effect of types of maleic anhydride-grafted polypropylene (MAPP) on the interfacial adhesion properties of bio-flour-filled polypropylene composites

The effect of processing temperature on the interfacial adhesion, mechanical properties and thermal stability of bio-flour-filled, polypropylene (PP) composites was examined as a function of five different maleic anhydride-grafted PP (MAPP) types. To investigate the effect on the interfacial adhesion of the composites, the five MAPP types were subjected to characterization tests. The MAPP-treated composites with sufficient molecular weight and maleic anhydride (MA) graft (%) showed improved mechanical and thermal stability. The enhanced interfacial adhesion, and mechanical and thermal stability of the MAPP-treated composites was strongly dependent on the amount of MA graft (%) and the MAPP molecular weight. The morphological properties of the MAPP-treated composites showed strong bonding and a paucity of pulled-out traces from the matrix in the two phases. In addition, the improved interfacial adhesion of the MAPP-treated composites was confirmed by spectral analysis of the chemical structure using attenuated total reflectance (FTIR-ATR). The crystallinity of PP, MAPP, MAPP-treated composites and non-treated composites was investigated using wide-angle X-ray scattering (WAXS) and differential scanning calorimetry (DSC).