(670f) Comparison of Hypervelocity Impact (HVI) Effects in Ultra-High Molecular Weight Polyethylene (UHMWPE) and Poly(methyl methacrylate) (PMMA)

Impact-induced glass transition in polymeric materials has been observed to increase energy dissipation during penetration, despite testing temperatures exceeding quasi-static glass transition temperatures. This increase in energy dissipation is an important consideration in materials selection for lightweight armor applications. A series of hypervelocity impacts (HVIs) was performed on samples of ultra-high molecular weight polyethylene (UHMWPE) and poly(methyl methacrylate) (PMMA). A relationship between back face debris cloud velocity and impact velocities over the range of 3-6 km/s was developed for each material. Thermal analysis was performed on the two material systems to determine quasi-static glass transition temperatures, as well as melting and crystallization temperatures. Apparent failure mechanisms in the samples, in conjunction with the thermal analysis, were used to explain the relative performance of each material. The amount of energy dissipated or diverted in the process of these high rate perforations was elucidated from a molecular perspective.