The effect of zinc oxide on the properties of ethylene-propylene rubbers
Polimery 2001, No 10, 678
SummaryInverse gas chromatography was used to study the monoallyl maleate- or monotetrahydrophthalate (THA)-modified zinc oxide surface properties. The modification reduced both the dispersive components of the ZnO surface energy and the parameters of interactions with polar substances (Table 1). Rheometric and mechanical properties of ethylene-propylene rubber (EPR) and ethylene-propylene-diene rubber (EPDR) were studied in relation to the addition of (mono- and di-)allyl maleate or (mono- and di-)allyl tetrahydrophthalate or itaconic acid. The diallyl esters were found to act as dicumyl peroxide curing co-agents in ethylene/propylene copolymers and to increase the crosslink density in the elastomers (Table 2). The monoallyl esters acted similarly, yet only when ZnO was present. The ZnO modified with these esters was less efficient than the unmodified ZnO as an activator of sulfur curing of the ethylene/propylene/diene terpolymer (Table 3). The mechanical property data (Tabies 4, 5) showed the ZnO modified with the curing co-agents, especially with those containing the carboxylic group, to reinforce EPR more than did the unmodified ZnO. The vulcanizates appeared to contain ionic aggregates acting as a type of slipping "network nodes" which could be split by trichloroacetic acid or ammonia.