Viscoelastic properties of liquid crystals of aqueous biopolymer solutions
Viscoelastic properties of liquid crystals of aqueous biopolymer solutions
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生物聚合物水溶液液晶的粘弹性
DOI：
10.1007/bf01134603
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发表时间：
1991
期刊：
影响因子：
2.3
通讯作者：
W. Kulicke
中科院分区：
文献类型：
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作者：
R. Oertel;W. Kulicke
用静态剪切流和振荡测量以及借助偏光显微镜研究了生物聚合物黄原胶（Mη= 1.6·106）和黄原胶（MW= 335 000）的水溶致相的形成，因为这些聚合物显示出与卷曲乙烯基聚合物非常不同的粘弹性。当将粘度作为浓度和剪切速率的函数作图时，黄原胶和黄原胶表现出在各向异性溶液中观察到的相同的典型行为。还观察到，在增加的剪切速率下，浓黄原胶溶液的第一法向应力差显示饱和效应。在振荡测量中，只有胆甾烷表现出储能模量的最大值。在黄原胶溶液的情况下不存在这样的弹性最大值可以归因于黄原胶螺旋的显著更高的柔性。根据Flory理论计算的临界浓度与实验测定值的比较表明，两相区明显比理论预测的要宽。这种偏差不能归因于聚合物的柔性，但是可以通过分子间相互作用来解释。与不带电荷的黄原胶相反，黄原胶除了吸引相互作用（H-键）之外还受到静电排斥力的影响。
The formation of aqueous, lyotropic phases of the biopolymers xanthan (Mη= 1.6·106) and schizophyllan (MW= 335 000) is investigated with stationary shear flow and oscillatory measurements, as well as with the aid of polarization microscopy, because these polymers show very different viscoelastic properties from coiled vinyl polymers. Xanthan and schizophyllan exhibit the same typical behavior observed in anisotropic solutions when the viscosity is plotted as a function of concentration and of shear rate. It has also been observed that the first normal stress difference for concentrated xanthan solutions shows a saturation effect at increasing shear rate. In oscillatory measurements only schizophyllan exhibits an maximum for the storage modulus. The absence of a such an elasticity maximum in the case of the xanthan solution may be attributed to the significantly higher flexibility of the xanthan helix. A comparison of the critical concentrations calculated according to Flory's theory and the experimentally determined values shows that the two-phase region is distinctly broader than the theory predicts. This deviation cannot be attributed to the flexibility of the polymer, but can, however, be explained by intermolecular interactions. In contrast to the non-charged schizophyllan the polyelectrolyte xanthan is affected in addition to the attractive interactions (H-bonds) by electrostatic repulsion forces.
Takahiro Sato：“半柔性聚合物溶液中的各向同性液晶相平衡：黄原胶，一种刚性聚电解质”聚合物。
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