Abstract
Polypropylene-barium sulfate (PP-BaSO4) composites were prepared by pretreating the filler with stearic acid, silane and polypropylene-g-maleic anhydride, respectively. The effects of the PP-BaSO4 interfacial interaction on the rheological properties and nucleation behaviour of the composites were studied. Surface treatment with reactive coupling agents enhanced the matrix-filler interfacial interaction and caused an increase in the melt viscosity, whereas the use of non-reactive coupling agents reduced the particle-particle interaction and led to a decrease in melt viscosity. The plain BaSO4 had a weak nucleating effect on PP. When the PP-BaSO4 interaction was enhanced, a remarkable increase in nucleation activity of the filler was observed. It is suggested that the enhanced adsorption of PP molecules onto the BaSO4 surface is of benefit in lowering the thermodynamic potential barrier for the formation of primary nuclei.