Effects of Strain Rate, Temperature, Crystallinity, and Surface Smoothness on Tensile Properties of PCTFE Plastic

Abstract

Many tests have been performed on polychlorotrifluoroethylene (PCTFE) materials at ambient and cryogenic temperatures, including an extensive test program* conducted to determine design data for PCTFE and other plastic materials at temperatures of 77°, -110°, -200°, -320° and -423°F. Conventional (low and medium) strain rates were used throughout the previous program, and the test results revealed that crystallinity had a marked effect on the mechanical properties of PCTFE, particularly at cryogenic temperatures. The cryogenic-temperature tests indicated that PCTFE samples with a smooth, molded surface finish had higher tensile strength and greater elongation than samples prepared with a machined surface. Early rocket engine and component performance tests supported these findings, and low-crystallinity PCTFE seals with a smooth, molded surface finish have been considered preferential for use in cryogenic temperature applications.