Flame retardant polypropylene reinforced with natural additives

Flame retardant polypropylene composites were modified with fibers and hybrid combination of natural additives (coconut, wood flour, and walnut shell fibers) with high-strength basalt fiber. The composites were subjected to strength tests and flammability analysis to assess the impact of the fibers on flame retardant material, with the fiber content of 5?20 wt%. Mechanical tests showed the positive effect of fibers on strengthening of polypropylene. The introduction of basalt fibers by 5 and 10 wt% increases the strength by 20 and 40 %, and stiffness by 60 and 160 %, respectively. Natural additives as hybrid reinforcement caused approximately 10 % increase in strength and more than twofold increase in stiffness of the composite materials. Burning behavior assessment showed that the use of natural fibers slows down the process of peak heat release by approximately 20 %. The paper also indicates the positive effect of water and accelerated thermal aging on the mechanical properties of the tested composites. The presented research results point the potential of composites with natural additives as construction materials.