Scanning electron microscope studies were conducted to characterize the erosion resistance of polymethyl methacrylate (PMMA), polycarbonate (PC), polytetrafluorethylene (PTFE), and ultra-high-molecular-weight polyethylene (UHMWPE). Erosion was caused by a jet of angular microparticles of crushed glass at normal incidence. Material built up above the original surface on all of the materials. As erosion progressed, this buildup disappeared. UHMWPE was the most resistant material and PMMA the least. The most favorable properties for high erosion resistance were high values of ultimate elongation, maximum service temperature, and strain energy and a low value of the modulus of elasticity. Erosion-rate-versus-time curves of PC and PTFE exhibited incubation, acceleration, and steady-state periods. PMMA also exhibited a deceleration period, and an incubation period with deposition was observed for UHMWPE. The material removal mechanism appeared to be similar to those for metals. Angular, cut-faceted surfaces, indicative of cutting wear, were observed. There was evidence of surface melting, which is believed to be the result of heat generated by impingement. Erosion due to spherical and angular particles was compared, and the optical transmittance characteristics were discussed. Erosion volumes are presented as functions of the depth, width, and width-depth ratio of the pit. These plots, unlike those for metallic materials, suggest two different trends. A power-law relation is presented to estimate the erosion rate.Presented at the 40th Annual Meeting in Las Vegas, Nevada May 6–9, 1985