Fabrication and Biodegradation Studies of Styrene-butadiene Rubber Composites Reinforced with Poly (Methyl Methacrylate) Grafted Coconut Shell Powder

Keywords

Coconut shell powder, Graft polymerization, Poly (methyl methacrylate), Mechanical properties, Biodegradation

Abstract

Studies on the use of natural fibers as reinforcing filler into synthetic rubbers have increased recently and opened up new industrial possibilities. Natural fibers have advantages such as the ease of availability, low cost, renewable, and biodegradable nature. However, the main disadvantage of natural fibers in polymer composites is the poor compatibility between fiber and matrix. Therefore, chemical treatments are carried out to modify the fiber surface. Grafting technique is usually used to modify natural fiber. Therefore, poly (methyl methacrylate) (PMMA) is successfully grafted onto coconut shell powder. The graft copolymers were characterized by Fourier transform infrared, X-ray powder diffraction, thermogravimetric analysis, and scanning electron microscopy. The grafted copolymers exhibited low crystallinity and increased thermal stability. Composites were fabricated using the grafted product as reinforcing filler in styrene-butadiene rubber (SBR) matrix. Cure characteristics, thermal transitions, mechanical properties, and the biodegradation behavior of the composites were examined. Glass transition temperature (Tg) of the composites increased with increase in percentage grafting. The filling of the grafted product caused the improved mechanical properties such as tensile strength, tear strength, and hardness. Biodegradation of the composites was more dependent on the presence of lignocellulosic fillers than on SBR matrix.