Swelling behavior and tensile properties of double-network elastomer

A double-network elastomer was designed using natural rubber through two-step vulcanization by appling a uniaxial extension during the 2nd vulcanization. The residual extension ratio of the double-networked natural rubber was changed from 1.00 to 3.85 in this study, and both swelling behavior and tensile properties were investigated for the double networks. The swelling rate was increased and also both the stiffness and the tensile strength at break were improved, as the residual extension ratio became higher. The toughness of the double-networked natural rubber became greater than that of the single-networked natural rubber by introducing the two-step vulcanization.