A pharmaceutical/medical rubber compound contains the following components: (A) a composition obtainable by crosslinking (a) 100 parts by weight of an isobutylene polymer having terminal alkenyl groups with (d) a hydrosilyl-containing compound in the presence of (b) from 5 to 100 parts by weight of a polyolefin and (c) from 5 to 100 parts by weight of polybutene during melt kneading, and (B) an ultra-high molecular weight polyethylene powder. Compared with conventional thermoplastic elastomers, the pharmaceutical/medical rubber compound and its molded article are free from deformations and have sufficient permanent set resistance even under high temperature conditions, have excellent mechanical properties, low water absorption property, low reactivity and superb gas barrier properties, and can withstand high-temperature sterilization.
