Towards selection chart of flame retardants for natural fibre reinforced polypropylene composites

The market of natural fibre thermoplastic composites NFTC is still developing. However, it is limited by the progress in optimising the process parameters and defining the functional additives. One of the most needed additives is the flame retardant FR material. Addition of excessive FRs can decrease the mechanical properties. Polypropylene PP reinforced with 30% natural fibres (flax, jute, hemp and sisal) are prepared using kneading and different FRs are mixed together. The effect of the different FRs on the flame retardance level, namely UL94, as well as the mechanical properties are studied. The studied FRs materials in this work are mineral, halogenated, halogen-free intumescent. Also, the effect of synergism with nanoclays and antimony trioxide is considered. Based on the mechanical properties and the flame retardance levels, a concept of FR selection chart is built considering only the both aspects of the tensile strength and flame retardance test UL94.