A porous hollow fiber membrane having a particle cutoff within the range of 1 to 10 .mu.m and a pure water permeate flow equal to or higher than 30,000 L/m.sup.2 /hr/100 kPa. This porous hollow fiber membrane can be prepared by a method including, while a spinning dope containing a base polymer as a material for forming the porous hollow fiber membrane, an additive used for facilitating a phase separation of the spinning dope, a solvent compatible with both the base polymer and the additive and a mass of microparticles insoluble to the compatible solvent and uniformly dispersed in a liquid medium and having an average particle size within the range of 1 to 20 .mu.m, and a coagulating liquid for forming the hollow fiber membrane is used, a step of forming the hollow fiber membrane according to a dry-wet spinning method or a wet spinning method, and a step of extracting and removing the microparticles by immersing the hollow fiber membrane, which has been spun, into an extracting solution effective to dissolve the microparticles, but ineffective to dissolve the base polymer.
A porous polyethylene hollow fiber membrane having a pore-size gradient across the inner and outer surfaces thereof is prepared by introducing, during the cooling step of a melt-spun polyethylene hollow fiber, a nitrogen flow and a solvent having a boiling point in the range of 30 to 80.degree. C. to the inner and outer surfaces of the melt-spun hollow fiber, respectively.
Polymer-ceramic mixed matrix compositions contain one or more organic polymers and a nano-sized dispersion of inorganic metal oxide particles which are dispersed throughout the composition. Materials have use in making membranes that act as transfer agents.
The present disclosure relates to improved efficient and effective systems and methods of manufacturing hydrophilic polyethersulfone (PES) membrane suitable for commercial applications and the resultant hydrophilic polyethersulfone (PES) membrane suitable for commercial applications produced thereby and includes methods of manufacturing hydrophilic polyethersulfone (PES) membrane comprising the acts of: providing hydrophobic PES membrane; prewetting the hydrophobic PES membrane in a sufficient amount of a liquid having a sufficiently low surface tension; exposing the wet hydrophobic PES membrane to a sufficient amount of an aqueous solution of oxidizer; and after the exposing act, heating the hydrophobic PES membrane for a sufficient time at a sufficient temperature and methods of manufacturing hydrophilic polyethersulfone (PES) membrane comprising the acts of: providing gel PES membrane; exposing the gel PES membrane to a sufficient amount of an aqueous solution of oxidizer; and after the exposing act, heating the hydrophobic PES membrane for a sufficient time at a sufficient temperature and the resulting products.
This invention provides a process for making microporous membranes from a polymer solution and the membranes therefrom. A thermal assist, such as heating of the polymer solution can be effected subsequent to shaping the solution, such as by forming a film, tube or hollow fiber of the solution under conditions that do not cause phase separation. In a preferred embodiment, the formed solution is briefly heated to generate a temperature gradient through the body of the formed solution. The polymer in solution then is precipitated to form a microporous structure. The formation of a wide variety of symmetric and asymmetric structures can be obtained using this process. Higher temperatures and/or longer heating times effected during the heating step result in larger pore sizes and different pore gradients in the final membrane product.
