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The current work investigated the effects of zinc borate (ZB), ammonium polyphosphate (APP)/ZB and alumina trihydrate (ATH)/ZB hybrids as flame retardants on the flammability, calorimetric, thermal and mechanical performances of empty fruit bunch (EFB) fiber reinforced epoxy composites. The formulations with concentration of 5, 10, 15 wt·% ZB and 15 wt·% APP/ZB, 15 wt·% ATH/ZB hybrids and the Control composite (EFB reinforced epoxy) were fabricated using resin infusion method. The composite containing 10 wt·% APP and 5 wt·% ZB was found to produce the highest flame retardancy in 12 s vertical Bunsen burner test and show promising results in terms of burn length, drip flame time and total flame time as obtained from 60 s vertical Bunsen burner. This could be attributed to the synergism that was created at this mass fraction between the hybrid of APP and ZB. Flexural properties did not change significantly with the inclusion of APP and ZB hybrid whereas tensile strength and elongation at break experienced an obvious reduction.

Expandable graphite (EG) weighing 3 wt%, 5 wt% and 7 wt% was incorporated into 20 wt% natural fiber (NF) reinforced epoxy and these composites were characterized using Bunsen burner test, bomb calorimeter, thermogravimetric analysis, dynamic mechanical analysis, combined confocal Raman-Atomic Force Microscope, tensile test, scanning electron microscopy and energy dispersive X-ray method. Two formulations with 3 wt% and 5 wt% EG coating were produced to investigate their flame retardancy in comparison to that of EG filled composites. Increasing EG fillers in the composites significantly improved the fire resistivity and thermal properties, this, however, was found to reduce the mechanical properties. When EG particles were used as intumescent coating, at least 5 wt% content of EG was necessary to provide the sufficient self-extinguishing properties. Chemical treatment of the NFs could considerably enhance the mechanical performances. The morphology of composites, graphite particles and their char were investigated.

Various compositions of epoxy/hardener with flame retardant (FR) as additives were used to produce natural fiber composite through the resin infusion technique. The effects of natural fiber (NF), ammonium polyphosphate (APP), alumina trihydrate (ATH) and ATH/APP hybrid on flammability, thermal and mechanical properties of the composites were investigated. Incorporation of NF into neat epoxy matrix reduced the gross heat of combustion with improved thermal degradation properties. Addition of APP enhanced the flame resistant properties of the composite with a much reduced total flame time and zero drip. The 10 wt·% ATH and 5 wt·% APP hybrid showed the most promising flame retardancy with a self-extinguishing property as well as the lowest gross heat and greatest char residue amongst the various formulations investigated. In general, the formulations containing only ATH couldn't provide the effective flame resistivity as compared to that of the APP-filled composites. The ATH-filled formulations reduced the tensile strength, elongation at break and flexural properties while an increase in the flexural strength of APP-loaded formulations was observed. An increase in moduli of the FR-filled composites was measured as compared to that of the NF/epoxy composite, owing to a more brittle characteristic.

This investigation studied the utilization of intumescent thermal resistive mats to provide surface protection to the core natural fibre-reinforced Elium® composite structural integrity. The intumescent mats contained flame retardant (FR) i.e. expandable graphite (EG) with four different expansion ratios and alumina trihydrate (ATH). All natural fibre thermoplastic composites were fabricated using a resin infusion technique. The impact of char thickness and chemical compositions on the flammability and smoke properties was investigated. It was found that surface protection significantly reduced the peak heat release rate, total smoke release, smoke extinction area and CO2 yield, and substantially enhanced UL-94 rating, time to ignition and residual char network, depending on the EG exfoliation ratio, ATH and mineral wool fibre. The glass transition temperature increased for the FR composites containing EG with lower expansion ratio. Inclusion of intumescent mats increased the strength of the composites while it had a negative effect on the modulus.