Effect of water exposure on dimensional stability and mechanical properties of unpurifed and purified maleated poly(butylene succinate) compatibilised poly(butylene succinate)/kenaf bast fibre composites

Kenaf bast fibre filled poly(butylene succinate) (PBS) composites were made with adding 65wt.% PBS, 30wt.% KBF and 5wt.% of unpurified or purified maleated PBS with concentrations of MA 3, 5, 7 and 10 phr. The composites were immersed in distilled water for a period of 90days. In general, the equilibrium water absorption, M-m, for composites with unpurified compatibilisers (PBSgMA) was higher than the uncompatibilised composites. The M-m for the composites also increased with MA concentration due to the increase of the water affinity. On the contrary, composites with purified compatibilisers (pPBSgMA) at 3, 5 and 7phr of MA concentrations have relatively lower M-m than the control composites due to the improved fibre-matrix interfacial adhesion. The water absorption of uncompatibilised and compatibilised composites was found to follow the Fickian behaviour. It can be seen that the exposure of those composites to the 90-day water immersion resulted in the deterioration of their dimensional stability. As expected, the flexural properties of the wet and redried composites were inferior to those of the control composites. The composites with purified compatibilisers have better recovery compared to composites with unpurified compatibilisers, and this result indicates that purification is essential to reduce water affinity, thus reducing the deriorating impact of water on the composites dimensional stability and mechanical properties.