The Effects of Rice Straw Weight Fraction and Particle Size on Thermal Conductivity and Mechanical Properties of Polypropylene Composite

Abstract

Polypropylene is a widely used material for various types of equipment. As a recyclable thermoplastic polymer, polypropylene composite provides an attractive quality of thermal insulation due to its heat-retaining property. The use of rice straw for filler in thermal insulating material is based on its low thermal conductivity, renewable material, and low cost production techniques. The composite were manufactured by melt-mixing of neat polypropylene and filler of various weight fractions, pellet formation, followed by reprocessing with injection molding. The current work focused on determining the effect of filler's weight fraction, particle size and pretreatment on the thermal conductivity and tensile strength of the composite. The result showed that an increase of filler's weight fraction up to 30% decreased the composite's thermal conductivity and tensile strength gradually. Composite of fine particles filler (325 mesh) gave a lower thermal conductivity and higher tensile strength than that of coarse particle (18-35 mesh). Composite with the lowest thermal conductivity of 1.39 W/mK was obtained at 30 w.% filler content and fine particles filler (325 mesh). Improvement on composite properties achieved by acetylated rice straw which enable to reduce straw's hydophylicity and enhance adhesion between matrix and filler.