Effect of fiber coating on the mechanical performance, water absorption and biodegradability of sisal fiber/natural rubber composite

Styrene butyl acrylate (SBA) copolymer latex nanoparticles which contain vinyltrimethoxysilane as binding agent were prepared using microemulsion polymerization and were used for coating sisal fiber. The structure of SBA and coated sisal fiber (CF) was confirmed by Fourier transform infrared spectroscopy. The effect of the surface coating of sisal fiber (SF) on the SF/natural rubber (NR) composite properties was systematically evaluated through curing characteristics, morphological properties, mechanical properties, water absorption resistance, biodegradability and dynamic mechanical analysis. As indicated from the morphological study, the coating of SF with SBA enhanced the interfacial adhesion between SF and the NR matrix. In addition, the tensile strength was improved by 26.9% and 43% after the addition of 5 and 10 phr (parts per hundred rubber), respectively, of CF to NR. The coating process improved the water resistance of SF/NR composite significantly especially at high SF loading level, where the composite that contained 30 phr CF absorbed 6.7% water compared to 13.2% for the composite containing uncoated sisal fiber (UF). Dynamic mechanical analysis confirmed that the coating process improved the interfacial adhesion between the SF and NR matrix as indicated from the higher values of storage modulus and lower values of maximum loss factor (tan delta(max)) recorded for composites containing CF compared to those containing UF. (c) 2021 Society of Industrial Chemistry.