The study on the fatigue and structural deformation of engineering plastics such as polyphenyleneether ( PPE), PPE/polystyrene (PS) alloy has been achieved by continuously viscoelastic method. The structural deformation of polymers in fatigue process was considered by measuring, the energy consumption due to dynamic loss modulus and heat generation, and their mutual relation. Fatigue life depended upon the contents of PPE as well as the fundamentally experimental conditions such as displacement. The ratios of the heat generation to the total energy consumption in fatigue process were about 4060 %. The higher the ratios were, the richer PPE contents in the polymer alloy were. The decreases of molecular weight of the specimens objected the fatigue tests were observed to be large enough to reduce the mechanical strength of the polymers. Although the energy consumed to cleavage the polymer chains were small, they were thought to contribute to reduce the mechanical strength of the specimens. It was possible that the heat generation related with entanglement density of polymers and the reduction of molecular weight as well as the defects in the specimen which generated newly during the fatigue tests played a important role for determining the fatigue lives.

View full abstract

The degradations of the plasticized polyvinylchloride (PVC) backed with polyurethane foam (PUF) under heating and Xe fade meter were investigated. The distributions of the plasticizer in the degraded PVC were measured by infrared microspectroscopy, and those of C=C bonds formed by dehydrochlorination were measured by derivatization-EPMA. In result, it was found that the plasticizer in the PVC migrated to PUF, and the migration caused decrease of the ultimate elongation of the PVC, in the both cases of heating and Xe fade-meter. However, the mechanism of migration of the plasticizer under Xe fade-meter was different from that under heating. On the other hand, dehydrochlori nation of PVC occurred from the interface, not from the exposed surface, in the both cases. By the amine degradation test, it was confirmed that the amine, which was used as catalyst for curing of PUF, accelerated the dehydrochlori nation of PVC.

View full abstract