Abstract:

Membranes which contain impermeable flakes or lamellae can show permeabilities much lower than conventional membranes. The variation of membrane permeability with flake volume fraction φ,flake aspect ratio α and slit aspect ratio δ is studied in this paper,and a new diffusion model in the barrier membranes is suggested:D ₀/D=1/δ+α²φ²/(1-φ).This model is verified by the diffusion experiments of varying flake volume fraction φ and varying aspect ratio α . It can be concluded that the diffusion is greatly retarded by two factors: the tight slits between the flakes,and the tortuous wiggles to get around the flakes. The 1/δ is the effect of the slits which decreases the cross-sectional area through which diffusion can occur,while the α²φ²/(1-φ) is the effect of the wiggles which both decrease the cross-sectional area and increase the length for diffusion through the barrier membrane.

摘要： 建立了溶剂分子透过聚合物层状共混物的扩散模型 ,给出了溶剂分子相对有效扩散系数D₀ /D与分散相体积分数、不可透薄片形状参数α以及薄片接头缺口参数δ之间的关系式 .经采用不同值及α值共混物得到的实验数据证明 ,该模型与实验结果吻合良好.