Preparation And Performance Of PVC Membrane With Micro Permeability

We need to prepare a kind of membrane materials called membrane with micro permeability whose coefficient of permeability is form10-8cm/s to10-6cm/s for the research and development project of Pisha sandstone modified damming.We selected the polyvinyl chloride (PVC) as the raw material of membrane and preparedthe PVC micro perm eability membrane that fulfill damming condition in this experiment.We discussed the influence of polymer concentration, additives, mixed solvent and gel-time on the water flux of the membranes. In the two-component system, the higher was the concentration of the polymer, the lower would be the water flux. The addition of water and ethanol made the water flux of the membrane increased and the addition of ethyl silicate made the water flux decreased. Within a certain range, the gel time was shorter, the pore size of membrane was smaller and the water was flux the lower.N, N-dimethyl formyl (DMF) and tetrahydrofuran (THF) were chosed to make mixed solvent. The results show that when the concentration of PVC was16%and the ratio of N, N-dimethyl formyl (DMF) and tetrahydrofuran (THF) was7:3, the water flux of the membrane was0.10L/(m2·h) and the permeability coefficient of the membrane was2.78×10-6cm/s. Also when the concentration of PVC was16%, the mass fraction of DMF was54%and the mass fraction of THF was30%, the water flux of the membrane was7.87×10-3L/(m2·h),and the permeability coefficient of the membrane was2.19×10-7cm/s. The permeability coefficient of these two kinds of membrane had met the water requirement of pisha sandstone.Then the physical properties and the mechanical properties of the membranes were tested and then we knew that the thickness of the former membrane was about0.200mm, the mass area ratio was about134.2g/m2,the tensile strength was about4.66KN/m, trapezoidal tearing strength was about33.34N, bursting strength was about846.6N and the thickness of the latter membrane was about0.204mm, the mass area ratio was about135.4g/m2,the tensile strength was about5.71KN/m, trapezoidal tearing strength was about34.42N, bursting strength was about853.4N. The strength of these two kinds of membrane conformed to the standards of the membrane which was used in project. These two kinds of membrane could be used in pisha sandstone dam project to make pisha sandstone wet appropriately.