Pre-oxidized mesophase pitch modified phenolic composites with mosaic-structured char layers and excellent ablation resistance

Currently, phenolic resin (PR) is widely used as a matrix for the polymer-based ablative materials in aerospace industry. In this paper, pre-oxidized mesophase pitch (OMP) modified boron phenolic composites (OMPBPR) and their fiber-reinforced composites were prepared. PLM and SEM analyses showed that the OMP can co-carbonize with resin matrix to construct a mosaic-structured char layer incorporated pitch-based graphitic carbon during ablation. Furthermore, mercury intrusion porosimeter, XRD, Raman and TEM analyses showed that the inlaid graphitic carbon can effectively hinder the growth of defects in amorphous carbon (AC) framework, while improve the graphitization degree of char layer. The results demonstrated that the linear and mass ablation rates of OMPBPR were optimally reduced by 109% and 27.1% compared to the counterpart, and the linear ablation rate of fiber-reinforced composite was also optimally reduced by 65.5%. The above results indicate that the novel OMPBPR-based composites are promising materials for application in thermal protection systems.

Automated summary

In this study, pre-oxidized mesophase pitch modified boron phenolic composites and their fiber-reinforced composites were prepared. The results showed that the pre-oxidized mesophase pitch can co-carbonize with the resin matrix, forming a mosaic-structured carbon layer and effectively hindering the growth of defects and improving the graphitization degree of the char layer. Compared to the counterpart, the linear and mass ablation rates of the modified composites were reduced significantly, making them promising materials for thermal protection systems.