Thermal Expansion of High Filler Content Cellulose-Plastic Composites

Abstract

The effects of resin content (10–30%), cellulose fiber length (120 and 300 micrometer), and molding conditions (press, injection, and extrusion molding) on the thermal expansion of high filler content cellulose/polypropylene composites were evaluated. Other physical properties such as densities, bending strengths, and water absorption of composites were also determined. The results indicated that thermal expansion of composites is dependent on the above conditions. Small thermal expansion was observed for composites with low resin (high cellulose) content. Composites with long fibers (300 micrometer) showed smaller thermal expansion than those of 120 micrometer, except for injection-molded composites with 20% resin content. Composites prepared by injection and extrusion molding showed anisotropy of thermal expansion depending on the parallel and perpendicular directions of molding. The results of thermal expansion are discussed in the light of other physical properties and the interaction of fibers in the composites.