Molecular motion and material properties of cosoluble polymer blends

共溶聚合物聚苯乙烯（PS）和聚乙烯基甲基醚（PVME）的共混物，瞬时变形和应力松弛和双折射的测量。由于两种聚合物链段光学各向异性的不同，可以从双折射率来估计各组分链段的变形程度，在PS长链和PVME短链的共混物中，松弛模量呈现两个橡胶态平台区。第一，在短时间内，具有较高的模量与两种聚合物组分的变形相结合：该区域中的应力由系统中的所有聚合物链段支撑。在第二平台区，应力完全由PS长链支撑，其模量与PS含量相同的PS溶液在低分子量的普通溶剂中的模量相等。在短时间内比溶液中的链更大的应力。当PVME失去形变效应时，明显由于PS-PVME缠结而产生的额外应力松弛。松弛速率不受长PS链的分子量的影响。这些结果证实了高分子链缠结的现代概念。

The blend of cosoluble polymers, polystyrene (PS) and poly(vinyl methyl ether), (PVME), was instantaneously deformed and the relaxation of stress and birefringence were measured. Owing to the difference of the segmental optical anisotropy of two polymers, one can estimate the degree of deformation of the segments of each component from the birefringence.In the case of the blend of long PS chains and short PVME chains, the relaxation modulus exhibited two rubbery plateau regions. One, at short times and with a higher modulus was corporated with the deformation of both polymer components: the stress in this region was supported by all the polymer segments in the system. A part of the modulus then relaxed as the short PVME chains lost the effect of deformation and became optically isotropic.The stress in the second plateau region was supported exclusively by the long PS chains and the modulus was equal to that of the PS solution, with the same PS content as the blend, in an ordinary solvent of low molecular weight.The PS chains in the blend supported;more stress at short times than the chains in the solution did. The extra stress, apparently due to the PS-PVME entanglement, relaxed as the PVME lost the effect of deformation. The rate of relaxation was not affected by the molecular weight of the long PS chains. These results substantiate the modern concept of the polymer chain entanglement.