Effect of novel intumescent flame retardant on mechanical and flame retardant properties of continuous glass fibre reinforced polypropylene composites

In this study, the influence of a novel intumescent flame retardant (IFR) on the mode I interlaminar fracture toughness and flame retardant properties of continuous glass fibre reinforced polypropylene (CGF/PP) composites is presented. The novel IFR system that consists of ammonium polyphosphate/poly (ethanediamine-1, 3, 5 triazine-o-4-amion-2, 2, 6, 6- tetramentylniperidine) (APP/PETAT) was introduced into the CGF/PP unidirectional prepregs (UD) composites by hot-melt impregnation process. Double cantilever beam (DCB) tests were performed to evaluate the mode I interlaminar fracture toughness (GIC) by using modified beam theory (MBT). It was found from the experimental results that compared to the neat CGF/PP composite, the mode I fracture toughness initiation toughness (GIC init.) and propagation toughness (GIC prop.) of CGF/PP/12.5 wt% IFR composites were increased by an average of 99.7% and 119.11% respectively. Meanwhile, samples with 12.5 wt% IFR could self-extinguish with an oxygen concentration of 32.4% and exhibit lower fire spread speed in UL-94 test. Furthermore, the peak of heat release rate (PHRR), total heat release (THR), fire performance index (FPI), and mass loss rate (MLR) tests indicated that IFR could dramatically enhance the flame retardancy of the composites.