abstract
Wax is commonly used as an antidegradant for rubber materials by formation of an
impervious barrier. Wax solubilities in natural rubber (NR), styrene–butadiene rubber
(SBR), and butadiene rubber (BR) vulcanizates were measured using wax solution in
toluene and molten wax. Wax solubilities using molten wax were much higher than those
using wax solution in toluene. The wax solubility of NR vulcanizate was higher than those
of SBR and BR. Parameters influencing wax solubility were the solvent swell, rubber
fraction and filler type as well as the rubber type. Molecular weight distribution of the
dissolved wax was different from that of the raw wax; the dissolved waxes with lower
molecular weights were relatively higher than the raw ones. We believe that wax solubility
and molecular weight distribution of the dissolved wax can be widely used for determining
the wax type and content.