Polyester moulding compounds of natural fibres and wollastonite

Abstract

Abstract Combination of natural fibres and wollastonite whiskers has been attempted as an alternative to glass fibre reinforcement in polyester dough moulding compounds. Natural fibres (sisal) and wollastonite were surface-modified with polyester compatible neo pentyl (diallyl) oxy, tri (dioctyl) pyro-phosphato titanate and gamma-methacryloxy propyl trimethoxy silane coupling agents, respectively. Reinforcing effect of wollastonite to a level of ∼50 wt% in an unsaturated polyester resin reveals a positive indication because of its favourable physico-mechanical properties and microstructural features. The optimization of short sisal and glass fibres in wollastonite/polyester system was carried out to formulate a doughy compound. It was found that ∼11 wt% sisal fibres in wollastonite/polyester and ∼3 to 5 wt% glass fibres in sisal/wollastonite/polyester give the optimum results. The high loss area observed at α and β transitions in dynamic mechanical analyser (DMA) traces supported the elastic behaviour of sisal/wollastonite/polyester moulding compared to corresponding wollastonite/polyester system. Based on these findings, a dough composition has been formulated and its suitability was assessed vis-a-vis to glass fibre–dough moulding compounds. It is observed that polyester dough moulding compound prepared from sisal/wollastonite reinforcement gives satisfactory results.