Detective work with high speed testing: The location of a phase change area

High speed tensile tests on Lexan polycarbonate resin were carried out on three grades of material at four test speeds from 200 to 15,000 in./min. and at five temperatures from −30 to +140°C. A consideration of the results of these tests led to a number of interesting conclusions. Among these conclusions was the identification of a plateau in the plots of some of the variables vs temperature in the 125° to 140°C. range. A more complete study of the variation in the tensile yield values of one of the grades of Lexan resin at 2 and 20 in./min. testing speed over the temperature range, and some‐what beyond, has been made to define this unusual effect.