Novel POSS coagent additives for HNBRs

摘要

HNBR is a widely used elastomer for which properties can be tailored through variation of the degree of nitrile and olefinic groups along the polymer chain.While partially hydrogenated HNBR can be crosslinked using sulfur and peroxide vulcanization,fully hydrogenated HNBR(/-HNBR)can only be cross-linked using peroxides(ref.1).Therefore,engineering physical properties of crosslinked/-HNBR are limited by the number and quality of crosslinks achievable through the peroxide induced abstraction of protons along the elastomer polymer chain.Coagents,such as triallyl cyanurate,zinc diacrylate,etc.,can be utilized to partially rectify the above deficiency by enhancing crosslink quantity and type between/-HNBR chains.However,as small molecules,these traditional coagents have only modest ability to control the spacing and thermomechani-cal dynamics of/-HNBR crosslinks.In this work,we introduce a new family of olefinic coagents based on polyhedral oligo-meric silsesquioxanes POSS(ref.2).POSS chemical additives are comprised of a rigid silicon-oxygen(SiO! 5)core with external organic groups that impart compatibility and reactivity;while the rigid cage core provides modulus(ref.3),thermal stability(ref.4),volume and surface area at the crosslink.