Study on influence of heat treatment on interfacial adhesion of CF/ PI composites

In order to improve the service performance of carbon fiber reinforced polyimide (CF/PI) composites, the interfacial adhesion and failure mechanism were investigated via micro-bond test. Composites were formed by carbon fiber (sized and unsized TG800) and PI matrix (KH308 and KH500), and various heat treatments were designed and performed on each system. The results of CF/PI composites after high-temperature treatments showed that the interfacial shear strength (IFSS) always increased and then decreased with the increasing temperate due to the change of failure modes, and the performance retention rate of composites formed by KH500 was much higher under the same treatment. While the IFSS results of composites formed by KH308 and KH500 after long-time treatments were completely different, reflecting the proper service temperature of CF/PI composites. Besides, although it would decompose during curing process, the sizing agents still increased the active functionality on fiber surfaces, contributing to the interfacial adhesion of CF/PI composites at high temperature.

Automated summary

The interfacial adhesion and failure mechanism of carbon fiber reinforced polyimide (CF/PI) composites were investigated through micro-bond tests. High-temperature treatments showed that the interfacial shear strength (IFSS) initially increased and then decreased with increasing temperature, with composites formed by KH500 exhibiting higher performance retention. The IFSS results of composites formed by KH308 and KH500 after long-time treatments were significantly different, indicating the proper service temperature of CF/PI composites. Despite decomposition during the curing process, sizing agents still enhanced the active functionality on fiber surfaces, contributing to the interfacial adhesion of CF/PI composites at high temperature.