High residual mechanical properties at elevated temperatures of carbon fiber/acetylene-functional benzoxazine composite

It is always of great practical significance to develop carbon fiber (CF) reinforced polymer composites with high residual mechanical properties at elevated temperatures for aerospace engineering structures, etc. In this work, the CF reinforced composite based on acetylene-functionalized benzoxazine (AFBEN) was manufactured by the resin transfer moulding (RTM) technology. The mechanical properties at elevated temperatures (150-350 °C) are first and systematically examined for the as-prepared CF/AFBEN composite. Differential scanning calorimetry and rheological characteristics are employed to evaluate the adaptability of AFBEN for the RTM process. Dynamic mechanical and thermogravimetric properties of the CF/AFBEN composite are also investigated to evaluate the thermal stability. The results display that the mechanical strengths of the CF/AFBEN composite exhibit the high residual rates of ca. 90% at 250 °C and over 60% at 350 °C compared to the mechanical properties at room temperature. The fracture mechanisms at room and elevated temperatures are studied and the fracture behavior of the CF/AFBEN composite is shown to transform from fiber-matrix interfacial debonding to resin matrix failure as the temperature increases. Consequently, the as-prepared CF/AFBEN composite show great potentials for practical applications in aerospace engineering structures, etc. due to its high residual mechanical properties at elevated temperatures and the ease of the RTM processing.