| Abstract: | The flexural fatigue properties were studied for PP injection-molded samples of different molecular weight and well-defined skin-core morphology (see Part I). It can be clearly seen that the crack initiation always occurs in the subskin layer of higher macromolecular orientation, and propagates towards the core. The mechanisms of cracking are discussed on the basis of fatigue kinetic data and analytical measurements on the stressed sections. The important influence of processing conditions, essentially holding pressure on the fatigue behavior is illustrated. |
