State of Dispersion – Mechanical Properties Correlation in Small Particle Filled Polymer Composites

Abstract

Abstract Correlation between state of dispersion and mechanical properties is obtained and failure mechanisms from falling weight impact tests are discussed. The state of dispersion is characterized for calcium carbonate filled polypropylene model composites by using a scanning electron microscope. A dispersion index is defined in terms of the fraction of agglomerates of the filler remained in the composites. Improvement of dispersion uplifts tensile strength and more prominently falling weight impact strength. It is pointed out that an initial failure in the falling weight impact test rises at the agglomerate existing near the loading point. Falling weight impact strength is found to be dependent upon the distance from loading point to failure initiation point where the agglomerate exists. This explains the dependency of impact strength on the state of dispersion and a large sample deviation often observed in the falling weight impact test.