Abstract
Fatigue behaviour of plastics is discussed by means of creep curves and the phenomenon of self heating. Amorphous thermoplastics such as polymethyl methacrylate (PMMA) and rigid suspension polyvinyl chloride (S-PVC) and partially crystalline polypropylene (PP) are examples. In practice, the first formation of crazes and microcracks and their defor mation have to be taken as a limit for mechanical loading rather than the ultimate failure.