Institut für Physik-NMR, Martin-Luther-Universität Halle-Wittenberg, Betty-Heimann-Straße 7, D-06120 Halle, Germany.
Phys Rev Lett. 2010 May 14;104(19):198305. doi: 10.1103/PhysRevLett.104.198305. Epub 2010 May 12.
We use a benchtop NMR technique to monitor entangled polymer melt dynamics over 5 decades in time covering regimes II-IV of the tube model. We confirm the familiar molar mass scaling exponents of the regime transitions, but we observe a mass-dependent time scaling exponent describing segmental fluctuations in the constrained-Rouse regime II up to high molecular weights. Local chain motions are thus governed by modes that are much less restricted than predicted by the tube model. Diluting protonated chains in deuterated invisible matrix chains, we prove that the exponent is determined by the matrix molecular weight, suggesting constraint-release effects as the origin.
我们使用台式 NMR 技术在 5 个时间decade 范围内监测缠结聚合物熔体动力学，涵盖管模型的 II-IV 区。我们确认了熟知的分子量标度指数，用于描述各过渡区，但我们发现了一个与分子量有关的时间标度指数，用于描述在受限的Rouse 区 II 中高分子量下的链段波动。因此，局部链运动受到的限制模式要比管模型预测的少得多。通过将质子化的链稀释到氘化的不可见基质链中，我们证明了这个指数是由基质分子量决定的，这表明约束释放效应是其起源。
