Two transparent plastic sheet materials, Selectron 44, a polyester, and 5105XP, an acrylate, were tested in tensile creep and creep rupture, crazing, short-time tensile, and deterioration at 80 degrees, 160 degrees, and 200 degrees F. Additional short-time tensile tests were made at 250 degrees, and 300 degrees F. The creep and creep-rupture tests indicated that the 5105XP material had considerably more strength than Selectron 44 at all three tests temperatures. The short-time tensile tests have a similar indication at 80 degrees, 160 degrees, and 200 degrees F, but at 250 degrees F Selectron 44 appeared to have a slight superiority in strength. At 300 degrees F, 5105XP had no practical load-carrying ability at all, while Selectron 44 showed a tensile strength of only 204 psi. Selectron 44 displayed no crazing whatsoever at any temperature or strain rate. The crazing strength of 5105XP was, in general, equal to or greater than the rupture strength of Selectron 44 at all three test temperatures.