Studies on Mechanical Properties, Thermal Degradation, and Combustion Behaviors of Poly(1,4-butylene terephthalate)/Glass Fiber/Cerium Hypophosphite Composites

This work aims to develop glass-fiber reinforced poly(1,4-butylene terephthalate) (GRPBT) composites with enhanced mechanical, thermal stability, and flame retardancy properties using a novel compound, cerium hypophosphite (CHP). Mechanical performance studies showed that both the storage modulus and the tensile strength increased first and then decreased with increasing CHP content. For the GRPBT composite with 15 wt % of CHP, the storage modulus value at 30 degrees C was 3 times that of GRPBT. Thermogravimetric analysis (TGA) illustrated that low loading of CHP could improve the thermal stability of GRPBT composites. The volatilized esters measured by TGA coupled with FTIR (TGA-FTIR) in the decomposition of GRPBT with 20 wt % of CHP are decreased by about 69%. The combustion properties were evaluated by limiting oxygen index (LOI), Underwriters Laboratories 94 (UL 94), and cone calorimeter testing. For GRPBT containing 20 wt % CHP, it achieved a V-0 classification with a high LOI (28.5%). Additionally, the peak heat release rate (PHRR) and total smoke production (TSP) were respectively reduced by around 76% and 45% as compared to the results obtained from GRPBT.