Preparation and sound insulation properties of thermoplastic elastomer composites with CaCO₃ filler

Composites of ceramic powders and an elastomer-based matrix were prepared by mixing CaCO₃ powders with polyethylene and polypropylene elastomers, and their mechanical and sound insulation properties were measured. CaCO₃ powders with 0.7 μm and 35 μm particle size were added to elastomers up to 80 wt%. Scanning electron microscopy photographs showed uniform distribution of the CaCO₃ powders in the matrix. While density and surface hardness increased, melt index, tensile strength and elongation of the composites decreased as the amount of added CaCO₃ powders increased. As more CaCO₃ powders were added sound transmission loss of the composites increased owing to the increase of density. Addition of 0.7 μm sized CaCO₃ powders resulted in a slightly higher transmission loss than the addition of 35 μm sized powders because of the increased interface area between the elastomer matrix and the CaCO₃ powders. Composites with a polyethylene matrix showed higher transmission loss than those with a polypropylene matrix because the tensile strength and hardness of the polyethylene-based composites were low and their elongation was high.