不同分子量可德胶水悬浮液的粘弹性研究

采用动态粘弹性测量研究了不同分子量的生物大分子可德胶 (Curdlan)水悬浮液 (ASC)的流变学特性 .室温下观察到ASC具有弹性 (Solid like)行为 ,储能模量G′在测量范围内轻微依赖频率 ,而损耗模量G″和损耗角正切tanδ存在最小值 .ASC粘弹性随可德胶分子量和浓度的增加而增强 .ASC的流动特性符合Herschel Bulkley模型 ;其弹性行为可以通过渗流理论的标度弹性模型来描述 .网络结构是由于可德胶颗粒聚集或絮凝而形成的 ,当可德胶含量超过临界浓度cs=0 3 %时 ,弹性模量G′与可德胶浓度存在标度关系G′=Goεt,其中标度指数t=2 5 4.

VISCOELASTICITY OF AQUEOUS SUSPENSIONS OF CURDLAN WITH DIFFERENT MOLECULAR WEIGHTS

The rheological properties of aqueous suspension of curdlan (ASC) with different molecular weights were investigated with dynamic viscoelastic experiments.Solid-like behavior for ASC was observed at room temperature.The storage shear modulus G′ demonstrated a slight frequency dependence over the range measured,whereas the loss shear modulus G″ and loss tangent δ showed a shallow minimum.The viscoelasticity of ASC increased with increasing molecular weight and concentration of curdlan.The flow curves were approximated by the Herschel-Bulkley rheological model.The fact that ASC manifests an elastic behavior is attributed to the formation of percolating network established by the aggregation or flocculation of curdlan particles,which can be described by the scalar elasticity model of percolation theory.The shear modulus G′ showed a scaling relationship with the curdlan concentration in excess of a threshold concentration c s=0 3%,G′=G oε t,where the scaling exponent t=2 54.