We present structural relaxation studies of a polystyrene star polymer after cessation of high-rate extensional flow. During the steady-state flow, the scattering pattern shows two sets of independent correlations peaks, reflecting the structure of a polymer confined in a fully oriented three-armed tube. Upon cessation of flow, the relaxation constitutes three distinct regimes. In a first regime, the perpendicular correlation peaks disappear, signifying disruption of the virtual tube. In a second regime, broad scattering arcs emerge, reflecting relaxation from highly aligned chains to more relaxed, still anisotropic form. New entanglements dominate the last relaxation regime where the scattering pattern evolves to a successively elliptical and circular pattern, reflecting relaxation via reptation.

中文翻译：

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伸长取向、适度拉伸的三臂星形聚合物结构松弛的小角中子散射研究

我们展示了在停止高速拉伸流动后聚苯乙烯星形聚合物的结构松弛研究。在稳态流动期间，散射模式显示出两组独立的相关峰，反映了限制在完全定向的三臂管中的聚合物的结构。在流动停止时，松弛构成三个不同的状态。在第一种情况下，垂直相关峰消失，表示虚拟管的破坏。在第二种情况下，出现了广泛的散射弧，反映了从高度对齐的链到更松弛的各向异性形式的松弛。新的纠缠支配了最后的弛豫状态，其中散射图案演变为连续的椭圆和圆形图案，通过爬行反映弛豫。