Depolymerization and ionic conductivity of enzymatically deproteinized natural rubber having epoxy group

Preparation of liquid epoxidized natural rubber (ENR) was made by oxidative depolymerization of ENR in latex stage without loss of epoxy group. Epoxidation of fresh natural rubber latex, which was purified by deproteinization with proteolytic enzyme and surfactant, was carried out with freshly prepared peracetic acid. The glass transition temperature (T-g) and gel content of the rubbers increased after the epoxidation, both of which were dependent upon an amount of peracetic acid. The gel content was significantly reduced by oxidative depolymerization of the rubber with (NH4)(2)S2O8 in the presence of propanal. The resulting liquid epoxidized rubber (M-n approximate to 10(4)) was found to have well-defined terminal groups, i.e. aldehyde groups and alpha-beta unsaturated carbonyl groups. The novel rubber was applied to transport Li+ as an ionic conducting medium, that is, solid polymer electrolyte. (C) 2003 Elsevier Ltd. All rights reserved.