Experimental determination of the effects of industrial oil immersion on polymer-based composites

Abstract

This paper presents a unique set of experimental data on the long-term oil immersion effects on various carbon fiber-reinforced thermoplastic composites. Five materials—unidirectional AS4/PEEK, unidirectional AS4/PPS, unidirectional AS4/PEI, woven AS4/PEI, and short random AS4/PFA—were immersed in oil and water for several months at four temperatures between room temperature and 80 °C. The weights of the four samples were monitored. The samples exposed to oil were tested via Dynamic Mechanical Analysis (DMA). The results show that the four AS4/PEEK, AS4/PPS, AS4/PEI and woven AS4/PEI composites did not exhibit any changes in thermo-mechanical properties. However, the Teflon-based composite showed significantly altered behavior despite no changes in weight. The glass transition temperature was lowered by 30 °C after a 2-month immersion in oil (independently of the temperature). No change in the glass transition temperature but a stiffness degradation was observed after immersion in water. A dramatic decrease in the glass transition temperature of reinforced PFA can be attributed solely to prolonged industrial oil contact including that at room temperature.