Department of Chemical and Biological Sciences, University of Huddersfield, Queensgate, Huddersfield HD1 3DH, UK.
Int J Biol Macromol. 2011 Oct 1;49(3):369-77. doi: 10.1016/j.ijbiomac.2011.05.014. Epub 2011 May 26.
The rheological properties and microstructure of aqueous oat β-glucan solutions varying in molecular weight were investigated. The structural features and molecular weights (MW) were characterized by (13)C NMR spectroscopy and high performance size-exclusion chromatography (HPSEC), respectively. The microstructure of the β-glucans dispersions was also examined by atomic force microscopy (AFM). The samples with β-glucan content between 78 and 86% on a dry weight basis had MW, intrinsic viscosity ([η]) and critical concentration (c*) in the range of 142-2800×10(3)g/mol, 1.7-7.2dl/g and 0.25-1.10g/dl, respectively. The flow and viscoelastic behaviour was highly dependent on MW and on the concentration of the β-glucans dispersions. Pseudoplastic behaviour was exhibited at high concentrations and Newtonian behaviour was evident at low concentrations. At the same concentration, the viscosity was higher for higher MW samples. The Cox-Merz rule was applicable for the lower molecular weight samples at higher concentrations whereas the high molecular weight sample deviated at concentrations greater than 1.0%, w/v. The mechanical spectra with variation of both MW and concentration were typical of entangled biopolymer solutions. AFM images revealed the formation of clusters or aggregates linked via individual polymer chains scattered heterogeneously throughout the system. The aggregate size increased with the molecular weight of the samples investigated and has been linked to the rheological behaviour of the samples.
研究了分子量不同的水性燕麦β-葡聚糖溶液的流变性质和微观结构。通过（13）C NMR 光谱和高效尺寸排阻色谱（HPSEC）分别对结构特征和分子量（MW）进行了表征。通过原子力显微镜（AFM）还检查了β-葡聚糖分散体的微观结构。β-葡聚糖含量在 78%至 86%（干重）之间的样品具有 142-2800×10（3）g/mol、1.7-7.2dl/g 和 0.25-1.10g/dl 的 MW、特性粘度([η])和临界浓度（c*）。流动和粘弹性行为高度依赖于 MW 和β-葡聚糖分散体的浓度。在高浓度下表现出假塑性行为，在低浓度下表现出牛顿行为。在相同的浓度下，MW 较高的样品具有较高的粘度。对于较低分子量的样品，Cox-Merz 规则在较高浓度下适用，而对于较高浓度（大于 1.0%，w/v）的高分子量样品则存在偏差。随着 MW 和浓度的变化，机械谱是典型的缠结生物聚合物溶液。AFM 图像显示了通过分散在整个系统中的单个聚合物链连接的簇或聚集体的形成。随着所研究样品的分子量的增加，聚集尺寸增加，并与样品的流变行为相关。
