Several recent papers and review assess fire safety solutions for composites using natural fibres in polymers. Such innovative new material solutions are developing in a range of applications, as industries look to include bio-based materials whilst achieving mechanical performance and low weight. Elsabbagh et al. compared different FRs in several natural fibre / polypropylene (thermoplastic) composites, showing that UL94-V0 can be achieved (30% flax fibres) with 28% total DECA (brominated FR) plus antimony or 26% ammonium polyphosphate (PIN FR), but with around 30% loss in tensile strength. Overall, the authors aim to develop an FR selection tool enabling to target objective fire performance, mechanical characteristics and regulatory requirements. Kim et al. review over one hundred studies on natural fibre reinforced composites, covering different fibres, additive and reactive flame retardants, fire modelling and transport and construction applications. They conclude that naturally fire resistant fibres, such as wool, combined with intumescent PIN flame retardants can offer effective fire performance, but that mechanical performance effects of the flame retardants and possible water uptake by and variability of the natural fibres are challenges. Marosi et al. review somewhat more widely flame retardancy of all bio-based polymer composites, including “self-reinforced” composites (where the fibres are made of the same polymer as the matrix). These have advantages for recycling (same polymer type) and can show good fire and mechanical performance with intumescent PIN FRs for bio-based polymers, including polylactic acid (PLA). PIN FRs are identified as preferable fire safety solutions because consistent with environmental objectives of selection of bio-based materials. Compatibility with recycling or biodegradability are key objectives.
“Towards selection chart of flame retardants for natural fibre reinforced polypropylene composites, A. Elsabbagh et al., Composites Part B 141 (2018) 1–8 https://doi.org/10.1016/j.compositesb.2017.12.020
“A review of flammability of natural fibre reinforced polymeric composites”, N. Kim et al., Composites Science and Technology 162 (2018) 64–78 https://doi.org/10.1016/j.compscitech.2018.04.016
“Fire-retardant recyclable and biobased polymer composites”, G. Marosi et al., in “Novel Fire Retardant Polymers and Composite Materials”, 2017. http://dx.doi.org/10.1016/B978-0-08-100136-3.00005-4