Preparation and characterization of hydrogenated natural rubber with hydroxyl groups

Abstract

An attempt to prepare hydrogenated natural rubber with hydroxyl groups was made by hydrogenation of epoxidized natural rubber (ENR) in latex stage after removal of proteins. The hydrogenation was carried out by reaction of deproteinized ENR (EDPNR) with hydrogen gas in latex stage with palladium black as the catalyst, in which EDPNR was prepared by epoxidation of natural rubber followed by deproteinization. Effects of dry rubber content, concentration of surfactant and feed of catalyst on the hydrogenation of EDPNR in latex stage were investigated to find the optimal condition for achieving the highest conversion. Characterization of the resulting hydrogenated EDPNR (HEDPNR) was carried out through NMR spectroscopy and size exclusion chromatography to prove introduction of hydroxyl groups into the rubber without chain scission. Mechanical properties, thermal aging properties and oil resistivity of HEDPNR were compared with those of natural rubber, deproteinized natural rubber and ethylene‐propylene‐diene rubber. It was found that tensile strength, permanent set, thermal resistance and oil resistance of natural rubber were rationally improved by hydrogenation of the rubber and introduction of the hydroxyl groups. Copyright © 2015 John Wiley & Sons, Ltd.