Supersoft Elasticity and Slow Dynamics of Isotropic-Genesis Polydomain Liquid Crystal Elastomers Investigated by Loading and Strain Rate Controlled Tests
Supersoft Elasticity and Slow Dynamics of Isotropic-Genesis Polydomain Liquid Crystal Elastomers Investigated by Loading and Strain Rate Controlled Tests
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通过加载和应变速率控制测试研究各向同性成因多域液晶弹性体的超软弹性和慢动力学
DOI：
10.1103/physreve.102.012701
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发表时间：
2020
影响因子：
2.4
通讯作者：
K.
中科院分区：
文献类型：
--
作者：
Takebe;A.;Urayama;K.
通过加载和应变速率控制实验，研究了各向同性成因多畴双相弹性体的超软弹性和慢动力学特性。加载控制试验揭示了拉伸驱动的多畴到单畴（PM）转变在真正的平衡条件下没有粘弹性（时间）的影响。平衡PM转变被观察为在具有极小幅度的阈值应力处的不连续尺寸变化（）。伴随PM转变的弹性体的80%伸长所需的机械功仅为高温各向同性状态下所需的机械功的2%，反映了超软弹性效应。恒定载荷下的尺寸增长率（）随着施加应力（）的接近而变低。然而，维度对缩减时间（）的依赖性与无关。在应变率控制试验中，应力-拉伸曲线在有限的拉伸范围内显示出PM转变的平台区特征，这相当于载荷控制试验中的不连续拉伸。平台应力随应变速率的降低而显著降低，而在实际可达到的低应变速率下（约），平台应力仍显著高于。的依赖性与加载控制测试中的依赖性几乎相似。这种相似性意味着，这两种类型的测试与不同的控制刺激是由相同的动力学的本地导演。
The supersoft elasticity and slow dynamics of isotropic-genesis polydomain nematic elastomers are investigated by loading- and strain-rate-controlled tests. Loading-controlled tests reveal the stretching-driven polydomain-to-monodomain (PM) transition under true equilibrium condition without viscoelastic (time) effect. The equilibrium PM transition is observed as a discontinuous dimensional change at a threshold stress with extremely small magnitude (). The mechanical work required for 80% elongation of the elastomer accompanying the PM transition is only 2% of that required in the high-temperature isotropic state, reflecting the supersoft elasticity effect. The dimensional growth rate () under constant loading becomes low as the imposed stress () approaches. The dependency of the dimension on the reduced time () is, however, independent of. In the strain-rate (ɛ̇) controlled tests, the stress-stretch curves show a plateau region characteristic of the PM transition in a finite range of stretch, which is equivalent to the discontinuous stretch in the loading-controlled tests. The plateau stresssignificantly decreases with decreasing ɛ̇, whereas theat the practically accessible low strain rate (on the order of) is still significantly higher than. The dependency ofon ɛ̇ is almost similar to the dependency ofonin the loading-controlled tests. This similarity signifies that the two types of tests with different controlled stimuli are governed by the same dynamics of the local director.