Direct Observation of Large Deformation and Fracture Behavior at the Crack Tip of Slide-Ring Gel
Direct Observation of Large Deformation and Fracture Behavior at the Crack Tip of Slide-Ring Gel
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DOI：
10.1149/2.0241909jes
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发表时间：
2019-04-23
影响因子：
3.9
通讯作者：
Ito, Kohzo
中科院分区：
文献类型：
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作者：
Liu, Chang;Mayumi, Koichi;Ito, Kohzo
滑环凝胶是由聚轮烷上的环交联而成的高度可变形的聚合物凝胶，其中环分子连接到线性聚合物链上。 SR凝胶的显着延展性归因于聚合物链上交联滑动所产生的应力均衡效应。我们通过将本能微米级缺陷放大为人工毫米级裂纹，然后基于光弹性绘制裂纹尖端应力场，直接观察应力均衡效果。通过减少 SR 凝胶中聚合物链上环的覆盖范围，观察到明显的裂纹钝化和延迟裂纹扩展。在裂纹扩展之前，裂纹尖端前方会出现长度为 0.6 mm、宽度小于 0.1 mm 的高度拉长的非线性“内聚区”。我们的结果表明，环覆盖率低的SR凝胶具有较大的内聚强度，可以在弹性链断裂之前承受大变形，这本质上是源于交联的滑动，自动调整链长度以均衡网络中的应力。 (C) 作者 2019 年。由 ECS 出版。
Slide-ring gel is a highly deformable polymer gel prepared by cross-linking rings on polyrotaxanes, in which ring molecules are threaded onto a linear polymer chain. The remarkable extensibility of SR gels is due to the stress equalization effect caused by the sliding of cross-links on polymer chains. We directly observed the stress equalization effect by magnifying the instinctive micron-scale defect to artificial millimeter-scale crack and then mapping the crack tip stress field based on photoelasticity. By reducing coverage of rings on polymer chains in SR gels, obvious crack blunting and delayed crack growth are observed. Highly elongated non-linear "cohesive zone" with length of 0.6 mm and width less than 0.1 mm occurs ahead of crack tip before crack propagation. Our results show that SR gels with low ring coverage have large cohesive strength to survive large deformation before elastic chains rupture, which is essentially derived from the sliding of the cross-links that adjusts strand length automatically to equalize stress in the network. (C) The Author(s) 2019. Published by ECS.