Rheological Properties of Isotactic Polypropylene/Alumina Composites

Melt rheological properties of alumina–filled isotactic polypropylene composites have been estimated at 0–22.2 vol% alumina at 493 K. The composite melts obeyed power law in shear stress-shear rate relations and were shear thinning. Apparent melt viscosity decreased initially up to 5.8% by volume alumina and increased with further increase in filler concentration. Melt elasticity decreased marginally upto φF = 5.8% whereas the data increased upon further increase in alumina content. Surface modification of alumina particles by a titanate coupling agent LICA 38 brought about interesting modification of the rheological properties through a plasticizing/lubricating function and/or blocking of the surface groups of Al2O3 particles.