WestChem, Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow G1 1Xl, United Kingdom.
Carbohydr Polym. 2013 Feb 15;92(2):1530-8. doi: 10.1016/j.carbpol.2012.09.047. Epub 2012 Nov 15.
The effect of structure creation and moisture content on the dielectric properties of amylose, amylopectin and amylose-stearic acid complexes is presented. Three dielectric features have been identified in these systems. At low temperature, a dipole relaxation process is observed which is assigned to the reorientation of the CH(2)OH group. At ambient temperatures, a thermally activated relaxation is assigned to liberation-local chain motion. In certain systems at high temperatures, a Maxwell Wagner Sillars process is observed associated with the heterogeneous nature of media and is ascribed to the gel structure in the amylose-stearic acid complex. The low temperature relaxation is sensitive to the moisture content, the water molecules being bound to the CH(2)OH groups and the activation energy being reduced as the water content is increased. Comparison of the relaxation observed in amylose and amylopectin indicates that chain branching increases the activation energy and inhibits the local reorientation motion of the chain backbone. The relative magnitude of the relaxation processes and their activation energies are discussed in term of the structure of the polymer backbone, the nature of the complex formed with stearic acid and the extent to which order is created by thermal treatment. This paper gives insight into the changes in amylose mobility accompanying the formation of the various complexes.
本文介绍了结构形成和水分含量对直链淀粉、支链淀粉和直链淀粉-硬脂酸复合物介电性能的影响。在这些体系中已经确定了三个介电特征。在低温下，观察到偶极子弛豫过程，该过程归因于 CH(2)OH 基团的重取向。在环境温度下，热激活弛豫被分配给释放-局部链运动。在某些高温系统中，观察到 Maxwell Wagner Sillars 过程，该过程与介质的非均相性质有关，并归因于直链淀粉-硬脂酸复合物中的凝胶结构。低温弛豫对水分含量敏感，水分子与 CH(2)OH 基团结合，随着水分含量的增加，活化能降低。直链淀粉和支链淀粉中观察到的弛豫的比较表明，链分支增加了活化能并抑制了链主链的局部重取向运动。通过聚合物主链的结构、与硬脂酸形成的复合物的性质以及热处理引起的有序程度，讨论了松弛过程的相对大小及其活化能。本文深入了解了在形成各种复合物时直链淀粉迁移率的变化。
