Mechanical, water uptake properties, and biodegradability of polystyrene-coated sisal fiber-reinforced high-density polyethylene

In this study, composites of high-density polyethylene (HDPE) with uncoated sisal fibers (UF) and that coated (CF) with polystyrene (PS) and vinyltrimethoxysilane (VTMS) copolymers (PSV) were fabricated. The prepared copolymers containing 2.5% VTMS (PSa) and 5% VTMS (PSb) were used to coat the sisal fiber with a thin layer of hydrophobic polymer to make coated fibers CFa and CFb, respectively. The coating process was verified by Fourier-transform infrared spectroscopy (FTIR) analysis. The mechanical, water absorption, morphology, and biodegradation properties of HDPE and its composites with UF (HUF) and CF (HCF) composites were evaluated. The tensile strength and flexural strength were improved by 19.5% and 34% after addition of 5% CFb to HDPE compared to HDPE composite which contains 5% UF. The results manifested significant reduction in the amount of water absorbed by CF and HCF composites compared to UF and HUF composites. Additionally, scanning electron micrographs indicated that the coating of sisal fibers with PSV improved the compatibility between sisal fibers and HDPE polymeric matrix. Also, the composites containing CF exhibited a lower rate of degradation than those containing UF.