Rheological Properties of Polypropylene/Hemp Fiber Composites

This study investigates the effect of hemp fibres on the shear and elongational rheology of polypropylene (PP). The parameters studied were hemp content (0-30%) and maleic anhydride polypropylene (MAPP) addition (0-0.6%). Shear rheology revealed that fibre content mainly influences low shear rate properties like yield stress and zero-shear-viscosity while coupling agent addition mainly influences intermediate to high shear rate parameters like relaxation time, power-law index and Yasuda parameter. On the other hand, elongational rheology results showed a strain softening behaviour of the composites with increasing consistency and decreasing strain at break as fibre concentration increases. MAPP addition is also shown to improve the fibre-polymer compatibility, but at the same time produces a plasticizing effect having a significant effect on rheological properties. POLYM. COMPOS., 30:1401-1407, 2009. (C) 2009 Society of Plastics Engineers