Mechanism of Water Absorption Behaviour in Groundnut Shell Powder Filled Waste HDPE Composites

Abstract

The mechanism of water absorption and its effect on mechanical properties of groundnut shell powder (GSP) reinforced waste high density polyethylene (wHDPE) was studied at different temperatures. The composite samples were developed via melt mixing and compression moulding techniques respectively. The percentage weight fraction of reinforcement was varied (0, 5, 10, 15, 20 and 25 %). The initial rate of water absorption and the maximum were observed to increase for all GSP filled wHDPE composites samples as the weight fraction of reinforcement increases. The maximum moisture uptake at room temperature was 4.77 % after 720 hours of exposure compared to 6.74 % moisture uptake at elevated temperature showing a 6.73 % increase for 25 % GSP-wHDPE composites. This indicates that sorption at room temperature takes longer time to reach equilibrium than sorption at elevated temperatures. The effects of moisture absorption and temperature on several performance parameters such as tensile strength, flexural strength, hardness value and impact strength revealed a decrease in these properties after 720 hours of immersion in distilled water at 27This indicates that long term exposure of GSP-wHDPE composites in water affects the interfacial adhesion between the polymer matrix and the fibre, creates de-bonding, leading to decrease in mechanical properties.