Preparation And Modification Of Electroplated Acetate Cellulose Porous Membrane

Electrospun cellulose acetate (CA) porous membrane has a lot of advantages, such as high hydrophilicity, good biocompatibility, high porosity, high surface to volume ratio, nontoxicity and environmental friendliness, which made it has great potential for application in water treatment, bioengineering, pharmaceutical and food industrie, and it has attracted a great deal of attention in science. However, the drawbacks such as poor tensile properties, structural instability, large pore size and a wide distribution of pore size have hindered its development and application. In this paper, we aimed at preparing CA porous membrane with good properties, so the electrospinning process of CA was studied, and it was improved by adding poly (vinylidene fluoride) (PVDF) and solvent vapour-treatment.Firstly, CA solution with different ratios of mixed solvent and concentration were prepared, then electrospinning under certain conditions to investigate the electrospinning parameters of CA, such as electrospinning voltage, electrospinning temperature, electrospinning velocity. The results showed that a solution of 19 wt% (mass fraction) CA in acetone/DMAc (volume ratio of 2/1) is more suitable to prepare electrospun CA porous membrane, and the optimized electrospinning conditions as following:15℃ of environmental temperature,12 kV of voltage,0.00075 mm/s of flow rates,20 cm of receiving distance,0.40 mm of needle diameter. Moreover, studies on properties showed that the CA porous membranes with different morphology have different crystallization characteristics, the tensile properties of CA porous membrane with beaded structure is the best, but the hydrophilicity of these porous membranes have little difference.Secondly, the properties of CA porous membrane was modified by electrospinning with mixed solution or double solutions. The electrospinning parameters of CA/PVDF porous membrane with mixed solution were investigated, and the optimized electrospinning conditions as following:16 wt% of CA/PVDF (9:1) concentration,2/1 (V/V) of acetone/DMAc,15℃ of environmental temperature,12 kV of voltage,0.00075 mm/s of flow rates,20 cm of receiving distance,0.40 mm of needle diameter. Furthermore, CA/PVDF porous membrane was prepared via electrospinning with CA solution and PVDF solution at the same time, and received the electropun nanofibers with a same receiver. The results showed that:both the two ways could improve the tensile properties of CA porous membrane, what’s more, the diameter and distribution of modified nanofibers were more uniform.Polyester (PET) nonwoven fabric was selected as the supporting layer, and CA/PVDF porous membrane was prepared with mixed solution, then the stability and pore-structure of CA/PVDF porous membrane were modified via solvent vapour-treatment. When modified the properties of prous membrane, the solvent vapour pressure was controlled by adjusting the ratios of mixed solvent, and changed the post-processing time, as a result, the crosslinking rate and degree of nanofibers were controlled, CA/PVDF porous membranes with different structure and pore size were successfully prepared. The mean pore size of the membranes were 80-1100 nm, their pure water flux were 120-7000 L/m2h, the rejection were 86-99%, the hydrophilicity and pollution resistibility of them were improved too.