Mechanical, viscoelastic, and flammability properties of polymer composites reinforced with novel Sirisha bark filler

Today is the era of advanced materials to resolve the issue due to ecological hazards. Research is being carried out to find the alternative of the existing materials with a low cost and eco-friendly nature. Polypropylene (PP) is one of the major commodity thermoplastics having wide applications worldwide. The neat PP is extremely sensitive to flame and therefore it is a challenging task for the researchers to reduce the flame sensitivity of PP composites for safe applications. Though the artificial flame retardant filler reduces the flame propagation, these are hazardous, costly, not environment friendly and, they reduce the mechanical strength of the polymer composites upon higher percentage loading. To overcome this difficulty, in this work, the novel natural Sirisha bark filler was reinforced to the coir fiber/PP hybrid composites to enhance the flame retardant and mechanical properties. The time to ignite (TTI) of the hybrid composites increased due to bark filler reinforcement in the composites and the flame spread reduced to zero. The impact strength of hybrid composites was found to be increased due to the strong interfacial adhesion of the bark filler with the PP matrix. The scanning electron microscope (SEM) micrographs revealed the well-defined grain boundaries of hybrid composites. The carbonaceous char coating over the surface of the hybrid composite was observed from the char morphology that acts as a hindrance to flame. The viscoelastic properties such as storage modulus, loss modulus, and loss tangent of the hybrid composites were studied by using dynamic mechanical analysis (DMA).