Abstract
The influence of physical aging on the creep compliance of polyetherether ketone (PEEK), a high temperature semicrystalline thermoplastic, is reported for loading in the compressive and flexural modes. These modes were investigated because, (1) these are relevant modes from a practical viewpoint, and (2) earlier studies in tensile and shear modes have indicated that the aging rates depended on the mode of loading. For PEEK at its equilibrium crystallinity of about 33 vol%, the aging shift rate at 130°C in the com pressive mode was found to be 0.89 ± 0.01 whereas in the flexural mode it was 1.01 ± 0.02. These parameters provide a quantitative measure of aging, and can be used for making long-term creep predictions at temperatures below the glass transition temperature.