The equilibrium nonlinear stress–stretch relationships for a monodomain main-chain nematic elastomer (MNE) are investigated by varying the angle between the stretching and initial director axes (θ₀). Angle θ₀ has pronounced effects on the ultimate elongation as well as on the width of the low stress plateau regime (Λ_p) during director rotation, whereas θ₀ has no appreciable effect on the plateau stress (σ_p). In the stretching normal to the initial director (θ₀ = 90°), the plateau end exceeds 200% strain. At oblique angles of 90° > θ₀ ≥ 35°, Λ_p decreases with decreasing θ₀, whereas the definite plateau regime vanishes at θ₀ < 24°. Wide-angle X-ray scattering and polarized optical microscopy measurements reveal that the director rotates uniformly in the biased direction for the MNE of θ₀° ≪ 90°, whereas directors rotating clockwise and counterclockwise are coexistent for θ₀ = 90°. Over the entire plateau regime, the MNEs exhibit pure shear deformation characterized by a Poisson's ratio of zero in the direction of the rotation axis. The Λ_p for the corresponding polydomain NE (PNE) undergoing a transition to the monodomain alignment is smaller than that of the MNE of θ₀ = 90°, while the σ_p values for both NEs are almost similar. The semi-soft elasticity concept satisfactorily explains the effects of θ₀ on Λ_p, and the Λ_p value of the PNE, using a single anisotropy parameter which is evaluated from the degree of thermally induced deformation of MNEs.

中文翻译：

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拉伸角度对主链液晶弹性体应力平稳行为的影响

为单畴主链向列弹性体（MNE）的平衡非线性应力-拉伸关系通过改变拉伸和初始导演轴线之间的角度研究了（θ ₀）。角θ ₀对极限伸长率以及在低应力平台制度（的宽度显着的效果Λ _p）导演旋转期间，而θ ₀对平稳应力（无明显影响σ _p）。在拉伸垂直于初始导演（θ ₀ = 90°），高原端超过200％的应变。以90°>倾斜角度θ ₀ ≥35°，Λ_p随减小θ ₀，而明确的高原政权消失在θ ₀ <24°。广角X射线散射和偏光显微镜测量表明，导演旋转均匀地在偏压方向的MNE θ ₀ °«90°，而主管旋转顺时针和逆时针共存为θ ₀ = 90°。在整个高原时期，多国企业表现出纯剪切变形，其特征是在旋转轴方向上的泊松比为零。所述Λ _p为相应的多畴NE（PNE）经历到单畴取向的转移比的MNE的较小θ ₀ = 90°，而σ _p为两个网元值几乎相似。半软弹性概念解释令人满意的效果θ ₀上Λ _p，和Λ _p的PNE的值，使用从跨国公司的热致变形的程度进行评价的单个各向异性参数。