Light‐scattering studies on solutions of cellulose in the ammonia / ammonium thiocyanate solvent system. II. Quasielastic light‐scattering and liquid crystal study
Light‐scattering studies on solutions of cellulose in the ammonia / ammonium thiocyanate solvent system. II. Quasielastic light‐scattering and liquid crystal study
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氨/硫氰酸铵溶剂体系中纤维素溶液的光散射研究 II。
DOI：
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发表时间：
1991
期刊：
影响因子：
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通讯作者：
J. Cuculo
中科院分区：
文献类型：
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作者：
A. D. Groot;D. Guinnup;M. Thiel;J. Cuculo
这是NH3 NH 4SCN纤维素溶剂系统的两部分研究的第二部分。用准弹性光散射法测定了纤维素在溶液中的扩散系数和溶解分子的有效流体动力学半径。此外，该系统进行了研究，使用光学显微镜，以确定最小临界体积分数或液晶形成。发现随着纤维素浓度的变化，扩散系数几乎没有变化，表明溶液中链之间的相互作用很小。对于聚合度为153和969的样品，测得的值为7.69和2.66 × 108 cm 2/s。与流体动力学体积的回转半径的系数的值被发现是在0.33至0.53的范围内，表示根据柯克伍德-里斯曼理论的扩展的线圈构象。对于所研究的三种溶剂组合物，液晶形成所需的最小临界体积分数ε 2′分别为0.039、0.038和0.048。基于实测的持续长度计算的α 2′值远大于预测值，表明与理论的严重偏离或系统中可能的聚集。
This is the second part of a two–part study of the NH3NH4SCN cellulose solvent system. Quasielastic light scattering was used to determine the diffusion coefficients of cellulose in solution and the effective hydrodynamic radius of the dissolved molecules. Additionally, the system was studied using light microscopy to determine the minimum critical volume fraction or liquid crystal formation. Very little change was found in the diffusion coefficients with change in cellulose concentration indicating little interaction between the chains in solution. Values of 7.69 and 2.66 × 108 cm2/s were measured for samples having a degree of polymerization of 153 and 969. The value of the coefficient relating the hydrodynamic volume to the radius of gyration was found to be in the range of 0.33 to 0.53, indicating an extended coil conformation according to the Kirkwood-Riseman theory. The minimum critical volume fractions necessary for liquid crystal formation, υ2′ were 0.039, 0.038, and 0.048 for the three solvent compositions studied. The values calculated for υ2′ based on the measured persistence lengths were much larger than the predicted values, indicating strong deviation from theory or possible aggregation in the system.