Effects of gamma radiation on the mechanical, thermal and morphological properties of particle filler reinforced thermoplastics

In this study, thermoplastic matrix composite specimens reinforced with natural and synthetic fillers were exposed to gamma irradiation, and the changes in their mechanical, thermal, and morphological properties were subsequently investigated. The results obtained after irradiation were compared with the pre-irradiation values, and the effects of gamma rays on the bonding mechanism between the matrix and reinforcement elements were discussed. Commonly used thermoplastics with different structural characteristics—such as low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), and polystyrene (PS)—were selected as matrix materials in the composites. Natural fillers such as banana fiber, seaweed, and straw, as well as synthetic-origin powder coating waste, were added to these matrices in varying proportions. The mixtures were first homogenized using an extrusion machine and then molded into standard tensile specimens using an injection molding machine. The prepared composite specimens were exposed to gamma radiation at a dose of 45 kGy and then subjected to tensile and flexural tests to assess their mechanical performance. Thermogravimetric analysis (TGA) was conducted to evaluate their thermal properties, while surface morphology was thoroughly examined using scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). As a result of these comprehensive analyses, it was observed that both the type of filler used and the application of gamma radiation played a decisive role in the overall properties of the composite materials. The post-irradiation data indicated that gamma radiation caused alterations in the bonding mechanisms between the filler and the matrix, as well as in the structural integrity of the composites.