动态膜渗透压法测量中的气球效应和液体粘附效应

Balloon and Liquid Adhesion Effect in Dynamic Membrane Osmometry Determination

用动态方法测量了半透膜对溶剂的透过速率及高聚物溶液的渗透压。膜在较大静压差的作用下所发生的弹性形变和液体在毛细管管壁上的粘附影响测量的复现性,导致了H～dH/dt关系偏离直线,使上升线与下降线不对称。

The influences of the balloon effect, i. e. the elastic deformation of the semipermeable membrane and the adhesion of liquids on the capillary, wall, on the measurement of solvent permeation rate and osmotic pressure of polymer solution were investigated by dynamic method theoretically and experimentally. The balloon effect leads to the departure from linearity of the plot of permeation rate of solvent against the hydrbstatic pressure difference. This effect could be described quantitatively by a deformation factor which is closely related with swelling ratio of the membrane in the solvent. The adhesion of liquids on the capillary wall influences the reproducibility of measurements and is the main reason for the occurrence of the unsymmetry of ascending and descending lines.