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

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 physicomechanical 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 recycledpolypropylene composites.