DOI: https://doi.org/10.55373/mjchem.v28i5.210

Keywords: Crosslinking, polystyrene, NR/PS blends, natural rubber, DVB, sensitizer

Abstract

Radiation-induced crosslinking is an effective technique for enhancing the performance of polymeric materials; however, excessive irradiation doses may lead to energy inefficiency, material degradation, and environmental concerns. This study aims to optimize the electron beam-induced crosslinking of a natural rubber/polystyrene (NR/PS) 60/40 blend by incorporating divinylbenzene (DVB) as a sensitizer, thereby improving its mechanical properties while reducing the required electron beam irradiation dose. The NR/PS 60/40 blends were prepared via melt blending and subjected to electron beam irradiation at doses ranging from 0 to 250 kGy, with and without the addition of 4.0 phr DVB. The crosslinking behavior was evaluated through gel content and swelling index measurements, while mechanical performance was assessed using tensile testing. The results showed that the NR/PS 60/40 blend containing 4.0 phr DVB achieved an optimum gel content of 92% in the NR phase at 100 kGy, whereas the NR/PS 60/40 blend without DVB required a higher irradiation dose of 150 kGy to achieve an optimum gel content of 93% in the NR phase. The optimum swelling index in the NR phase was observed at 150 kGy for both blends; however, the NR/PS 60/40 blend containing 4.0 phr DVB exhibited a lower swelling index of 8.0 compared with 9.2 for the NR/PS 60/40 blend without DVB, confirming a higher crosslink density. Furthermore, the NR/PS 60/40 blend containing 4.0 phr DVB exhibited the optimum tensile strength of 8.6 MPa at 150 kGy, whereas the NR/PS 60/40 blend without DVB achieved 7.9 MPa at 200 kGy. These findings demonstrate that incorporating 4.0 phr DVB enables NR/PS 60/40 blends to achieve comparable crosslinking and mechanical performance at a lower electron beam irradiation dose, thereby improving processing efficiency while minimizing the potential for radiation-induced degradation.