Effect of Gamma Irradiation on Crosslink Density and Chemical Characteristics of Gadolinium Oxide-Natural Rubber Vulcanizate Composite

Natural rubber is a polymer that has been widely used in various industrial applications because of its high flexibility. In this study, vulcanizates were developed from SiO2-reinforced natural rubber with added Gd₂O₃. Vulcanizate composites containing 0, 5, and 10 phr of Gd₂O₃ were fabricated to evaluate the combined effect of inorganic fillers and gamma irradiation. All composites were irradiate with gamma rays at a dose of 100 kGy and were evaluated for their chemical characteristic, swelling behavior, and crosslink density. Fourier Transform Infrared (FTIR) analysis showed that gamma irradiation induces significant structural changes in the natural rubber vulcanizate. These changes were confirmed by the emergence of new absorption peaks assigned to O-H and C=C groups in the FTIR spectra. Swelling and crosslink density measurements showed that gamma irradiation increased the vulcanizate’s crosslink density, indicating the formation of a stiffer polymer network. On average, the crosslink density increased by approximately 11%, accompanied by a 9.07% decrease in swelling. These finding highlight the synergistic role of SiO2 and Gd₂O₃ under gamma irradiation in improving the integrity of natural rubber based composites.