Effect of a Cross‐Linking Agent Concentration and Gamma Irradiation Dose on the Rigid <scp>PVC</scp> Stability

ABSTRACT In this work, the effect of the cross‐linking agent trimethylolpropane triacrylate (TMPTA) and gamma irradiation on commercial rigid PVC compounds were evaluated. Compounds containing 1–5 phr of TMPTA were irradiated at doses of 30, 40, and 50 kGy and subsequently characterized by FTIR, TGA, DSC, gel content, and mechanical testing. The yellowing index was also monitored during thermal aging in an automatic oven. FTIR analysis showed that irradiation induced changes in the PVC structure, while the presence of TMPTA minimized alterations in the characteristic PVC bands, suggesting a protective effect against degradation. Gel content increased with both TMPTA concentration and irradiation dose, confirming cross‐linking, which was consistent with thermal residues of up to 20% at 500°C in TGA. The glass transition temperature increased by up to 4°C for the 5 phr TMPTA formulation at 50 kGy, and the Young's modulus reached 3200 MPa, indicating enhanced stiffness. During thermal aging at 180°C, the samples showed progressive yellowing, although no significant changes in chemical functional groups were detected. Overall, TMPTA improved the thermal stability of PVC while preserving its mechanical integrity under irradiation and thermal exposure.