Water Hyacinth Fiber as a Bio-Based Carbon Source for Intumescent Flame-Retardant Poly (Butylene Succinate) Composites

In this study, flame-retardant poly (butylene succinate) (PBS) composites were developed utilizing a bio-based intumescent flame retardant (IFR) system. Water hyacinth fiber (WHF) was used as a bio-based carbon source, while ammonium polyphosphate (APP) served as both an acid source and a blowing agent. Effects of WHF:APP weight ratio and total IFR content on the thermal stability and flammability of WHF/APP/PBS composites were investigated. The results demonstrated that the 15WHF/30APP/PBS composite with a WHF to APP ratio of 1:2 and a total IFR content of 45 wt% had a maximum limiting oxygen index (LOI) value of 28.8% and acquired good flame retardancy, with a UL-94 V-0 rating without polymer-melt dripping. Additionally, its peak heat release rate (pHRR) and total heat release (THR) were, respectively, 53% and 42% lower than those of the neat PBS. Char residue analysis revealed that the optimal WHF:APP ratio and total IFR content promoted the formation of a high graphitized intumescent char with a continuous and dense structure. In comparison to the neat PBS, the tensile modulus of the 15WHF/30APP/PBS composite increased by 163%. Findings suggested the possibility of employing WHF, a natural fiber, as an alternative carbon source for intumescent flame-retardant PBS composites.