Study on UV resistance of high density polyethylene composite using waste gypsum

Abstract

Every year, a large amount of waste gypsum, a by-product of fertilizer production, was produced and landfilled that increasing the harm to the environment. In this study, for the purpose of utilizing waste gypsum, it was studied as the filler in blend of high density polyethylene (HDPE) and ethyelene vinyl acetated (EVA) with anti UV additives in order to improve the mechanical strength and lifespan of this composite. After using ethylene bis stearamide (EBS) to modify waste gypsum, modified waste gypsum (mGyp) and anti-UV additives at various contents were dispersed into HDPE/EVA blend by melt-mixing method to obtain HDPE/EVA/mGyp composites. As the results, the color difference and tensile strength of composite using additives did not changed much after 20 cycles of accelerated weathering test. In the presence of anti-UV additives, the photodegradation process was inhibited by showing the low carbonyl index of composite compared with samples without additives. Beside, the structure of composite using anti-UV additives is smooth and without cracks after accelerated weathering test as observed in SEM images. That led to the tensile strength of sample did not change much.