1. Introduction Butyl rubber (IIR) is a synthetic elastomer known for its exceptional impermeability to gases, high damping capacity, and resistance to weathering, ozone, and chemicals. Unlike general-purpose rubbers (like natural rubber or SBR) which rely on crystallisation for strength, butyl rubber derives its unique properties from its molecular structure: a saturated polyisobutylene backbone with a small percentage of isoprene comonomer to introduce unsaturation for vulcanisation.