As part of the Underwriters Laboratory evaluation of the physical performance of polymeric materials with respect to temperature, heat aging experiments are performed. These involve conditioning specimens for a pre-defined time at a constant temperature and subsequently measuring their tensile properties. The retention of these properties is calculated with respect to a control and is used as a measure of the thermal aging performance. The outstanding percentage retention of tensile strength and elongation to break for natural PEEK polymer is plotted versus conditioning time in Figure 21.

Information reprinted with permission from Victrex PLC