An Experimental Study of Polymer-Filler Redistribution in Injection Molded Parts

The migration of filler particles in polymer composite materials during the injection molding process is investigated. Results indicate that during injection, particle concentration becomes non-uniform in the molded part. Experiments were conducted with polystyrene filled with non-rigid (rubber) and rigid (calcium carbonate) particles. A plasma etching technique has been used to determine the local concentration of rubber particles in the molded part. An ashing technique was employed to determine the average concentration of calcium carbonate at various regions of the molded part. The experimental results show that process variables like injection speed, particle size, particle concentration, and nature of filler determine the final filler distribution in the polymer matrix.