Improving flame retardancy in glass fiber reinforced polyphthalamide composites

This study investigates the mechanical, thermal, and flammability properties of glass fiber (GF) reinforced polyphthalamide (PPA)composites with the addition of flame retardant (FR) additive and zeolite. The tensile and flexural strengths of the composites were obtained to decrease upon the addition of FR and zeolite, with PPA-GFexhibiting the highest tensile strength of 195 MPa. IzodImpact testing revealed a similar trend, where both notched and unnotched impact strengths were reduced by the incorporation of these additives. Scanning electron microscopy (SEM) indicated poor adhesion between glass fibers and the PPA matrix. The flame retardancy of the composites improved significantly with FR addition, achieving a V0 rating for the thicknesses of 1.5 mm and 3 mm and increasing the LOI value from 23.8% to 49.3% with the inclusion of 16 wt% FR and 2 wt% zeolite. Thermogravimetric analysis (TGA) displayed that the degradation temperatures of the composites were minimally affected by the additives, although FR addition led to the formation of a secondary degradation step. Differential scanning calorimetry (DSC) results demonstrated that FR addition reduced the crystallinity of the composites, while zeolite increased it, acting as a nucleating agent within the polymer matrix. The most effective zeolite concentration for enhancing crystallinity was found to be 1 wt%.