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Study on Concentrated Solutions of Stiff-Chain Polymers : Thermodynamic and Viscoelastic Properties

硬链聚合物浓溶液的研究：热力学和粘弹性能

基本信息

批准号：
01470108
负责人：
TERAMOTO Akio
金额：
$ 4.03万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1989
资助国家：
日本
起止时间：
1989 至 1990
项目状态：
已结题

项目摘要

The isotropic-liquid crystal phase boundary concentrations, osmotic pressure, and zero-shear viscosity were measured for concentrated solutions of two stiff-chain polymers, poly (hexyl isocyanate) (PHIC) and xanthan, a double-helical polysaccharide. The former is a neutral polymer, while the latter is a polyelectrolyte. It turned out that all the experimental data obtained cannot be described by current theories for rod-like and semi-flexible polymer solutions. We modified the current statistical-mechanical theories and also proposed a new dynamic theory of stiff-chain polymers in isotropic solution as described below.1. The scaled particle (SP) theory of Cotter for neutral straight spherocylinders was extended to semiflexible polymer solutions to calculate the isotropic-liquid crystal phase boundaries and osmotic pressure of the solution. Both quantities calculated were compared favorably with the experimental data PHIC and schizophyllan (a triple helical polysaccharide) solutions.2. The Helmholtz free energy of rod-like and worm-like polyelectrolyte solutions was formulated from a perturbation theory, where the hard core and electrostatic potentials between two polymers were taken as the pair potentials of the reference system and the perturbation, respectively. The free energy of the reference system was obtained from the SP theory, while the perturbation terms were evaluated by the second virial approximation. The agreement between theory and experiment of aqueous xanthan was almost quantitative in the phase boundaries, but not good in osmotic pressure.3. A viscosity equation for stiff-chain polymer solutions dilution through concentration was formulated by replacing the stiff chain by the "fuzzy cylinder" model. This equation describe well the dependence of the zero-shear viscosity on polymer concentration C and molecular weight M for isotropic soltions of xanthan and schizophyllan over wide ranges of C and M.

的各向同性液晶相边界浓度，渗透压，和零剪切粘度测定两个刚性链聚合物，聚（异氰酸己酯）（PHIC）和黄原胶，双螺旋多糖的浓溶液。前者是中性聚合物，而后者是中性聚合物。结果表明，所有的实验数据不能用现有的棒状和半柔性聚合物溶液的理论来描述。我们修改了当前的统计力学理论，并提出了一种新的各向同性溶液中硬链聚合物的动力学理论，如下所述。1.将Cotter的中性直球圆柱体标度粒子（SP）理论推广到半柔性聚合物溶液中，计算了各向同性液晶相界和溶液的渗透压。计算的两个量与PHIC和Escherophyllan（一种三螺旋多糖）溶液的实验数据进行了比较.从微扰理论出发，将两种聚合物之间的硬核势和静电势分别作为参考系和微扰的对势，计算了棒状和蠕虫状聚合物溶液的亥姆霍兹自由能.参考系的自由能由SP理论得到，微扰项由第二维里近似计算。黄原胶水溶液在相界的理论与实验结果基本吻合，但在渗透压方面的理论与实验结果吻合不好.用“模糊圆柱”模型代替刚性链，建立了刚性链聚合物溶液稀释浓缩的粘度方程。该方程较好地描述了黄原胶和黄原胶各向同性溶液的零剪切粘度与聚合物浓度C和分子量M的关系。