Evaluation of oil fly ash as a light stabilizer for epoxy composites: Accelerated weathering study

Residual oil fly ash (OFA) was used in epoxy pipe formulations for total or partial replacement of commercial light stabilizer i.e. Hostavin^® N24 without influencing the thermal or mechanical properties of the pipes. The optimum amount of OFA was identified as 4 wt% in a previous study and used here to prepare a composite for complete replacement of commercial light stabilizer. For this purpose, the optimum amount of OFA filled epoxy composite, based on bisphenol-A liquid epoxy, is prepared via in-situ co-polymerization with isophorone diamine as curing agent in the presence of 4 wt% of OFA as filler. The epoxy composites comprising 0.5 wt% Hostavin^® N24 (control) and a mixture of 2 wt% OFA and 0.25 wt% Hostavin^® N24 were also prepared for comparison with 4 wt% OFA sample to investigate the possibility of complete or partial replacement of commercial light stabilizer in epoxy pipe formulations. The developed epoxy composites were subjected to 0.5-6 months of accelerated weathering. At each interval, the effects of exposure on the composites were characterized by morphology, FT-IR, mechanical and thermal properties. The results of characterizations reveal that the 4 wt% OFA can completely replace the commercial light stabilizer in epoxy composites for industrial pipes formulations. This replacement will not have any significant impact on the thermal or mechanical properties of the composites. The significance of the effect on mechanical properties was established by using statistical analysis tools.