Mechanical Properties versus Flammability of New/Recycled Polypropylene/Flax/Magnesium Hydroxide composites

摘要

Natural fibre reinforced polymer composites (NFRP) are nowadays receiving a growing interest, especially in automobile and civil engineering profiles industries. Reduction of the flammability besides to keeping their mechanical properties will ensure wider market of these composites. Polypropylene (PP) matrix is reinforced with 30 and 50 wt% of flax fibres. Magnesium hydroxide Mg(OH)_2 is added at different levels of 0, 20 and 30 wt% to investigate the flammable resistance behaviour. Limited oxygen index (LOI) is improved to more than 27 with 50% flax/30% magnesium hydroxide. Although very slow burn rating in the horizontal test condition is achieved with 30/30, 50/20 and 50/30 wt% for flax/magnesium hydroxides respectively, no sample passed vertical burn test. Recycling of these is investigated and shows 4 and 10% drop in strength and stiffness. Recycling experiments on 50/30 system shows an effect of 5% LOI drop after reprocessing for two cycles.