Influence of orientation and volume fraction of Aramid fabric on abrasive wear performance of polyethersulfone composites

In case of fabric reinforced composites of specialty polymers influence of orientation of fabric and its volume fraction on tribo-behaviour is sparingly studied. In our earlier work, we have reported on the influence of amount of Aramid fabric (AF) in polyethersulfone (PES) on abrasive wear performance. However, orientation effect of fabric with respect to abrading plane was not investigated. In this work three orientations of composites of PES containing Aramid (Kevlar 29) fabric with three concentrations 64, 72 and 83 wt.% were selected to study the influence on abrasive wear performance. Composites developed by compression molding technique were characterized for their mechanical and physical properties. The abrasive wear performance of the composites was evaluated by abrading 10 mm x 10 mm x 10 mm sample against silicon carbide (SiC) paper under various loads and two grades of abrasive papers. The fabric reinforcement enhanced the abrasive wear resistance of PES significantly (approximately 1.35-9.46 times depending on the operating conditions). It was observed that 83% fabric composite showed the highest resistance to abrasive wear and impact along with the best tensile strength and elongation properties. Its flexural strength and ILSS values, however, were the lowest. Sixty-four percent fabric composite, on the other hand, showed an exactly reverse trend among the three composites. Among the three orientations, fibres in normal and parallel (N-P) and normal and anti-parallel (N-AP) direction with respect to sliding plane proved to impart maximum wear resistance. N-P was best for light loads while N-AP was best for high loading conditions. Orientation parallel and anti-parallel (P-AP) was least beneficial in this respect. Moreover, the extent of improvement very much depended on the operating parameters such as grit size and load. Benefits endowed due to reinforcement were higher at less coarse grade paper. With increase in load. however, wear rate of composites with N-P orientation increased and for other two orientations it decreased. Thus, for severe operating conditions, N-AP orientation proved to be most beneficial. SEM studies proved supporting for understanding the influence of orientation on wear performance. (c) 2005 Elsevier B.V. All rights reserved.