Effect of wettability and ageing conditions on the physical and mechanical properties of uniaxially oriented jute-roving-reinforced polyester composites

In order to obtain reliable composite materials in structural applications and to utilise fully the potential of reinforcing fibres, both perfect impregnation and strong interfacial bond formation have to be guaranteed. In the present study the tensile, flexural, and impact behaviour of jute roving reinforced polyester composites were investigated as a function of fibre loading and fibre surface wettability. Two types of unsaturated polyesters viz; (a) Resana having a wetting agent and (b) Elekeiroz without wetting agent, were used to study the influence fibre surface wettability. It was noted that Resana polyester composites showed mechanical properties superior to those of Elekeiroz composites. The impact strength of the Resana polyester composite with 30% fibre content was found to be 80 J/M-2, which is about 350% higher than that of the polyester matrix. Jute rovings were alkali treated in 10% aqueous NaOH solution for 3 h periods under two different conditions, i.e. (a) immersion at room temperature and (b) reflux at 100 degrees C. It was observed that jute rovings refluxed in alkali for 3 h showed better tensile properties than those treated at room temperature. The mechanical properties of the jute Resana polyester composites were evaluated under three ageing conditions, i.e. (1) immersion in water at 50 degrees C for 48 h (2) under reflux in water for 2 h; and (3) thermal ageing in an air circulating oven at 100 degrees C for periods up to 8 days. Our results indicate that the composites refluxed in water for 2 h showed a slight improvement in their tensile properties compared to those of immersion-aged composites. It was observed that thermal ageing tended to decrease the composite mechanical properties, which was attributed to oxidative degradation of both fibre and matrix. (C) 2000 Elsevier Science Ltd. All rights reserved.