Synergistic effects of gamma irradiation and Delonix regia pods bio-waste on the physico-mechanical properties of recycled-polypropylene composites: A design of experiment approach

Abstract

Gamma radiation technology to modify the various characteristics and properties of natural fiber reinforced polymer composites has been utilized at a vast rate. In the present study, composites of recycled-polypropylene reinforced with bio-waste Delonix regia pods have been prepared via extrusion and injection moulding and irradiated with gamma dose. A total of 9 experiments having 3 levels (10 wt%, 20 wt%, and 30 wt%) of fiber loadings and 3 varying levels (0 kGy, 10 kGy, and 25 kGy) of gamma dose as the process parameters have been tested for tensile and flexural responses. The optimum of Delonix regia (%) and gamma dose (kGy) for physico-mechanical properties were scrutinized using Response Surface Methodology based on full factorial design. Based on this model, optimum of Delonix regia and gamma dose were predicted to be 24.97% and 10.55 kGy which yielded the best mechanical properties simultaneously. The structural and morphological alterations were investigated using Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry, and X-Ray diffraction analysis. In addition, the thermal stability of optimized composites persists after gamma irradiation. It signifies the positive influence of both Delonix regia and gamma doses on the recycled-polypropylene composites.