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 become higher. The toughness of the double-networked natural rubber become greater than of the single-networked natural rubber by introducing the two-step vulcanization.

천연고무를 이용하여 일축방향으로 신장율을 달리한 상태에서 2단계 가교과정을 거쳐 이중망상을 설계하였다. 잔류신장율은 1.00에서 3.85까지 변화시켰고 이들 이중망상의 팽윤거동과 인장특성을 살폈다. 이중망상의 팽윤거동은 잔류신장율이 커질수록 팽윤속도가 상승하였고 잔류신장율의 증가로 강성도와 인장강도가 크게 향상되었다. 이중망상의 질김도는 2단계 가교의 도입으로 기존의 단일망상보다 높은 결과를 얻을 수 있었다.

Keywords: double networks; natural rubber; swelling; tensile strength; toughness