Effects of organophosphorus and mineral based flame retardants on combustibility and mechanical performances of natural fiber reinforced composites

Abstract

Purpose The study aimed to investigate epoxy composites reinforced with mechanical performances, thermal decomposition and ignitibility of natural fiber (NF) and doped with 5 wt.% of varying flame-retardant (FR) compounds. The incorporation of ammonium polyphosphate (APP) and zinc borate (ZB) showed improvement in modulus and elongation to break compared to the empty fruit bunch-filled epoxy (control). However, slightly lower tensile and impact strengths were recorded in all FR-containing composites. Design/methodology/approach Among the FR-loaded specimens, enhancement in flexural property was observed in composites with APP, whereas the addition of ZB and alumina trihydrate (ATH) resulted in the reduction of flexural strength. Thermogravimetric analysis results indicated that the introduction of APP and ATH negatively impacted the thermal degradation temperature (Td) of the NF-filled composites. Greater mass residue with FR-filled composites, where increment was in the range from 32-80 per cent compared to the control, was observed, with the greatest being the ZB-containing formulation. Vertical Bunsen burner experiment revealed that the addition of ZB and APP led to a zero dripping flame system, whereas such a phenomenon was absent in both the control and NF composites loaded with ATH. The bomb calorimeter results revealed that addition of NF into neat epoxy significantly enhanced the FR behavior of the composite, and the gross heat of combustion was greatly reduced when FRs were incorporated into the control sample. Findings Results from the current study concluded that non-halogenated FRs including APP, ZB and ATH were able to enhance the fire retardancy of EFB epoxy composite without significantly deteriorate the mechanical behaviors. Originality/value It can be shown from scanning electron microscopy micrographs that the fabrication technique produced composites with good interfacial adhesion between NF and epoxy matrix, and homogenous distribution of FRs were achieved.