The by-product abundances of fly ash allow them to be used as the reinforcing filler for high-volume and high-performance thermoplastic composites. However, the durability of the composites remains questioned as polymer degradation during environmental weathering creates brittle materials, leading to surface cracks, which potentially release hazardous fly ash particles into the environment. This paper reports the effect of environmental ageing (UV and moisture exposure) on the morphological and mechanical properties of fly ash mixed high-density polyethylene (FA/HDPE) composites with three dissimilar weight fractions (5, 10 and 15 wt%) of filler and compared the results with similarly aged neat HDPE samples. The consequence of environmental ageing on the elevated mechanical properties of composites is investigated. Fifteen wt% fly ash reinforced composite appears to have better morphological and mechanical properties after 20 weeks of ageing, with only ~5 and ~9% reduction in Young's modulus and tensile strength, respectively. The driving factors controlling the ageing effects are broadly discussed and recommendations are made for research advancements.
Keywords: HDPE; environmental ageing; fly ash; mechanical properties; polymer composite.