Study on mechanical properties of PBT matrix composites reinforced with surface-modified recycled glass fiber for propellant liner applications

The development of flame-retardant composites with outstanding mechanical features is critical for enhancing the safety and performance of propellant liners in solid rocket motors. This study investigates the mechanical properties of polybutylene terephthalate (PBT) composites reinforced with surface-modified recycled glass fiber (RGF). The surface modification of RGF was done with the cationic surfactant cetyltrimethylammonium bromide (CTAB) and the silane coupling agent γ-ammino-propyltriethoxysilane (KH550) as the modifying agents. In this experiment, the modified RGF/PBT composites were prepared by injection moulding method. The chemical structure of modified RGF was investigated by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The mechanical properties of RGF/PBT composites were investigated by tensile test, impact test and bending test. The results showed that the experiment successfully introduced CTAB and KH550 to the surface of RGF, and prepared surface-modified RGF, which improved the interfacial bonding strength between RGF and PBT matrix, resulting in the improvement of the mechanical properties of the modified RGF/PBT composites, and the RGF composites obtained by the KH550 modification had better properties. The improved impact resistance and mechanical stability of the modified RGF-PBT composites suggest their potential use as insulation materials in high-energy systems, such as protective casings for energetic formulations in pyrotechnics and propellant applications.