IMPROVED AGING AND UV RESISTANCE OF TPEs DERIVED FROM 'DIIMIDE-HYDROGENATED' EMULSION SBRs CONTAINING A BOUND ANTIOXIDANT

摘要

Several interesting features to the thermooxidative and photooxidative behavior of HSBRs with and without a polymer bound antioxidant have been observed. Most important is the observation that HSBRs containing a bound amine-type antioxidant and moderate hydrogenation levels (83-86%) can greatly outperform HSBRs with similar saturation levels without the bound antioxidant with regard to aged property retention under thermal and photolytic conditions. It also appears that the HSBRs with a bound antioxidant and these modest hydrogenation levels can approach the thermal resistance of even very highly saturated (97%+) HSBR (without antioxidant). [2]Secondarily, the incorporation of a polymer bound antioxidant into an emulsion SBR and subsequently into an HSBR does not interfere with the latex diimide reduction process or the ultimate generation of TPE properties. The antioxidant molecule, because of its large size, must be excluded from the polyethylene-like crystallites and concentrate in the amorphous rubbery domains where antioxidant protection is most needed.Additionally, variation of styrene levels between 2.5 and 6.7 mole % in the HSBRs studied had little influence on polymer aging properties, but was noticeable in affecting the initial level of polymer crystallinity as measured by DSC.