Valorization of oil palm frond ash via alkaline activation as reinforcement in polypropylene composites

Composites are widely used due to their excellent mechanical and physical properties. The trend has shifted from using synthetic fillers to natural fillers nowadays as they are more environmentally friendly and biodegradable. Malaysia is one of the largest producers of oil palm, generates abundant by-products such as oil palm fronds that can be valorized as fillers in polymer composites. In this study, different loading of oil palm fronds ash (OPFA) and alkali-activated oil palm fronds ash (AAOPFA) were added into polypropylene (PP) matrix to produce PP/OPFA and PP/AAOPFA composites through injection molding. The alkaline activation (AA) was carried out using 10 M sodium hydroxide and sodium silicate at a liquid-to-liquid (L/L) ratio of 2.5 and a solid-to-liquid ratio of 0.6. The tensile properties, water absorption, morphological, spectroscopy, thermal degradation and electrical conductivity of the composites were analyzed. Results showed that PP/AAOPFA composites at 10 parts per hundred resin (phr) exhibited the highest tensile strength with a 22.3% improvement, and the lowest water uptake, with a 14.5% reduction compared to PP/OPFA composites. Less void and filler pull-out were observed in the micrograph of PP/AAOPFA composites in comparison to PP/OPFA composites. The PP/AAOPFA composites enhanced the electrical conductivity of 2.5% and exhibited better thermal stability compared to PP/OPFA at any filler loading. These findings highlight the potential of PP/AAOPFA composites for sustainable applications in packaging and automotive industries.