Conclusions
The HDPE/RH composites were more brittle with the addition of the milled RH. Their flexural and the tensile strengths increased with the silica-rich RH contents. An improvement of all the flexural, tensile and impact strength was evident when MA-g-PE was added at around 5.0 wt% of RH. Microscopic observations revealed some RH pulled-out and numerous interfacial cavities within the untreated HDPE/RH composites. However, the interfacial adhesion was significantly improved when MA-g-PE was employed. Prolonged outdoor exposure to UV led to color fading. Water absorption was reduced when the MA-g-PE was incorporated in the HDPE/RH composites.