Effect of Resin Matrices on Thermal Stability, Mechanical, and Ablation Properties of Carbon Fiber-Reinforced Resin Composites

Carbon fiber-reinforced composites made with phenolic resin (Ph), cyanate ester resin (CE), and benzoxazine resin (BZ) were studied for their thermal stability, mechanical characteristics, and ablation resistance. Using thermogravimetric analyzer, the char yield and thermal stability of three resin matrices and their carbon fiber composite were evaluated. In comparison with phenolic resin, benzoxazine resin, and their carbon fiber composites, cyanate ester resin and carbon fiber–cyanate resin composites exhibited greater thermal stability and char yield. The ablation characteristics of carbon fiber composites were correlated with these data. Interlaminar shear strength of carbon fiber–cyanate ester composite (C-CE) was about 50% higher than carbon fiber–phenolic resin composite (C-Ph) and carbon fiber–benzoxazine resin composites(C-BZ). Flexural strength of C-CE composite was about 10% higher than C-Ph and C-BZ composites. When ablation tests were performed at heat fluxes of 125 W/cm2 and 500 W/cm2, it was discovered that the mass ablation rates for the C-CE composite were lower than those for the C-Ph and C-BZ composites. Scanning electron microscopy studies of ablated surfaces of three matrices composite indicate less damage to fibers in C-CE composite at both heat flux levels as compared to C-Ph composite and C-BZ composite. According to the current study, C-CE outperforms traditional C-Ph composites utilized in thermal protection systems as an ablative composite.