The processing of the thermoplastic composites can cause matrix thermo-oxidative degradation. Understanding the level of thermo-oxidative degradation, as well as the thresholds of temperature and processing time, allows the manufacture of high performance composites with higher crashworthiness. This study evaluated the matrix thermo-oxidative degradation by Friedman's isoconversional kinetic model to a carbon fiber/polyamide (CF/PA) commingled fabric. In addition, the CF/PA commingled composite was manufactured by consolidation under pressure at 240°C, 250°C, 260°C, 270°C and 280°C to observe the influence of the matrix thermo-oxidative degradation on its energy absorption capacity. Impact test and compression after impact (CAI) determined the energy absorbed by the CF/PA commingled composite at different processing temperatures. The results demonstrated that the matrix thermo-oxidative degradation affected the energy absorption capacity of the CF/PA composite when the processing temperature exceeded 260°C, which is in accordance with the prediction of the degradation study. Therefore, the optimal processing cycle occurs at 260°C for 20min. When it processed in temperatures above 260°C, the CF/PA commingled composite reduces in 0.14J/°C the energy absorption ability due to the matrix degradation in high temperatures, leading to a considerable reduction on crashworthiness and its performance.

The commingled technology is a promising technique for the manufacture of composites reinforced with natural fibers. This study presents the development, processing and basic characterization of a long fiber Jute/Polypropylene (Jute/PP) commingled composite. The Jute/PP fabric was produced in a handloom and the composite was consolidated by compression molding. The PP matrix was chemically and thermally characterized to certify its chemical composition and define its melting and crystallization temperatures. The degradation behavior of jute fibers was also studied by Friedman’s kinetic isoconversional model using thermogravimetric analyses (TGA). The mechanical properties of jute reinforcement and Jute/PP composite were characterized by tensile strength tests and by fractographic study of the fracture surfaces. Its tensile strength (44.62±6.02 MPa) and elasticity modulus (7.10±2.34 GPa) are approximate to the ones obtained by other processing techniques, suggesting that the developed commingled process can work as a low cost and practical alternative methodology for manufacturing of more sustainable composites in industries.