Response surface methodology based analysis of the impact of nanoclay addition on the wear resistance of polypropylene

Abstract

The addition of nanoclay in the polypropylene matrix has many applications in the field of automotive, packaging and aeronautical industry. Nanocomposites of polypropylene with nanoclay phr (part per hundred of resin) of 2.5, 5.0, 7.5 and 10 are prepared using melt mixing in twin-screw extruder and injection molding. The dispersion of nanoclay in the polypropylene matrix played a significant role in the preparation of nanocomposites. The freeze-fractured microstructures of the 5 phr of nanoclay composites shows better dispersion of clay particles in the polypropylene matrix. Tensile testing is performed to quantify the strength with respect to nanoclay phr in the nanocomposites. Stress strain behaviors during the tensile testing along with critical examining using field emission scanning electron microscope of the fracture surface have evolved that phr value around 5 provide maximum strength. In addition to this, surface roughness of these nanocomposites also indicate that the nanocomposites formed by 5 phr nanoclay give better surface finish. The wear behavior of nanocomposites is investigated using pin-on-disc tribo-tester at different loads (10, 20 and 30 N) and sliding speeds (0.5, 1.5 and 2.5 m/s). A response surface methodology based model is developed to explore the impact of nanoclay phr along with load and sliding speed on the wear behavior of these nanocomposites. Response surface methodology is a statistical technique in which the interaction among process variables is studies. It uses a sequence of design experiments to get an optimal response. It was found that 4.19 phr provides to be optimal value of nanoclay content exhibiting better wear resistance. Present study of composites with nanoclay reinforcement in polypropylene matrix concludes that phr value ranging around 4 to 5 gives best results.