An investigation on the flammability and dynamic mechanical behavior of coir fibers reinforced polymer composites

Recently, the natural fibers replaced the synthetic fibers to a great extent as reinforcement to the polymer composites. Among the natural fibers, coir fibers has the potential to be used in various applications because of its abundancy, non-toxicity, low cost, and resilient properties. Generally, the polymeric materials are very sensitive to the flame. That is why it is inevitable to measure the performance of the polymer composites prior to the applications such as construction, automotive parts, etc. Coir fibers have high lignin content that makes it a preferable reinforcement in the development of polymer composites to enhance the fire resistant properties. The aim of this work is to study the flammability properties of coir fibers reinforced polypropylene composites along with the thermal stability and mechanical properties. Composites were fabricated by melt compounding with micro-compounder followed by compression molding. The dynamic mechanical properties were analyzed. The storage modulus of coir/polypropylene composites was found to be increased than the neat polypropylene but the damping properties of the composites were decreased. The flammability properties have been studied using horizontal burning test by UL-94. It is observed from the study that the composites with 30 wt% of coir fibers content achieved V-0 rating. The flame propagation speed increased for composites up to 20 wt% of coir fibers content and after that it was decreased. The thermal stability of the composites was found to be increased with the increase in fiber loading.