Investigations on wear and frictional properties of kenaf fibre polyurethane composites under dry and wet contact conditions

Abstract

In this paper, an investigation was conducted to understand the wear and frictional properties of kenaf fibre reinforced polyurethane composites. The effect of applied loads (30 to 80 N), sliding distance (up to 2.7 km), and fibre orientation [i.e., parallel (P-O), anti-parallel (AP-O) and normal (N-O)] were determined under dry and wet contact sliding. Specific wear rates for all fibre orientations improved under wet contact except parallel orientated composites. Presence of water in wet sliding has significantly reduced the friction coefficient compared to dry sliding besides acting as a cooling agent. A scanning electron microscope (SEM) was used to study the worn surfaces and wear mechanism encountered. The predominant wear mechanism observed under dry sliding was micro-cracks, plastic deformation and thermo-mechanical deformation. Meanwhile, the worn surfaces under wet contact are very minimal, namely micro-ploughing at elevated sliding distances.