Flexural behavior of thermoplastic pultruded composites at elevated temperatures

This study evaluates the flexural behavior of pultruded glass fiber (GF) reinforced thermoplastic composites at elevated temperatures, based on polyphenylene sulfide (PPS), polyamide (PA6), and polypropylene (PP) matrix. The profiles were produced from preconsolidated composite tapes which were fabricated through the melt-impregnation process and then consolidated using pultrusion. Flexural tests conducted within the range of 21 °C to 280 °C showed distinct differences in thermal-mechanical performance of tested profiles. The GF/PPS composite profiles showed the highest thermal stability, maintain the flexural strength of 34.6 MPa at 260 °C, and over 50% of initial stiffness at 160 °C. The GF/PA6 profiles exhibited superior strength performance at room temperature which reached a value of 447.7 MPa and displayed moderate high-temperature resistance to test conditions. The GF/PP profiles showed performance decline which occurred at temperatures beyond 120 °C. The thermogravimetric analysis TGA and dynamic mechanical analysis DMA demonstrated that GF/PPS composites exhibited superior thermal resistance because they retained their original decomposition point until 374 °C and their glass transition point until 109 °C. Mahieux and Bosze models accurately described GF/PPS and GF/PA6 composite behavior whereas the Ha-Springer and Gibson models showed better results for GF/PP composite rapid degradation. The results underscore the importance of proper matrix selection and modeling accuracy for high-temperature composite design.