Hydrolytic Effects on the Modulus of Polyester Fibers

The effect of temperature and time of exposure in water on the initial modulus of various types of polyester fibers was investigated. Polyester filaments were tested in a constant-temperature water bath on the Instron tester. Various temperatures and times of exposure were used, and tests were made immediately upon attaining the desired time of exposure and after allowing the water bath to cool to equilibrium conditions. Within the experimental range of this study, the initial modulus of the polyester fibers decreased markedly above the second-order transition temperature of the polyester. An added decrease in initial modulus occurred after the fibers were exposed at this temperature for two hours. These were not found to be permanent effects.