Hollow fiber membranes having improved toughness and durability are prepared using a vinylidene fluoride polymer-containing component, such as Kynaro resins, having relatively low crystallinity. One aspect of the invention provides a membrane in the form of a fiber, wherein i) the fiber has a porous wall of a polymeric component enclosing a central hollow space extending the length of the fiber, ii) the polymeric component has a crystallinity as determined by wide angle x-ray diffraction of less than about 35%, iii) the polymeric component is comprised of at least one homopolymer or copolymer of vinylidene fluoride and iv) the membrane has an energy to break of at least about 0.5 J per square mm of membrane cross section.

A method suppresses membrane thickness variation and air resistance variation after a compression at 60° C. or 80° C. Stretching is performed at least twice in at least different axial directions before the extraction of the solvent, and at the same time, at least one of (i) and (ii) is satisfied. (i) The step (c) is a first stretching step of stretching the sheet-shaped product at least once in a sheet transport direction (MD direction) and at least once in a sheet width direction (TD direction) individually, and the MD stretching magnification and the TD stretching magnification in the step (c) satisfy (TD stretching magnification≥MD stretching magnification−2). (ii) The stretching temperature (T1) of a first axial stretching performed firstly in the step (c) and the maximal stretching temperature (T2) of a second stretching performed after the first axial stretching satisfy (T1−T2≥0).

A method of preparing a membrane comprising the steps of: a) mixing together a membrane-forming polymer, a water-soluble polyetheramine, and a solvent, said mixture containing no component which will react chemically with the polyetheramine; and b) casting said mixture to form the polymer into a solid membrane.

Membranes having first and second porous portions, wherein the first portion has a more open pore structure than the second portion, wherein the first porous portion includes channels prepared by removing introduced fibers, as well as methods of making and using the membranes, are disclosed.

Membranes comprising first and second microporous surfaces, and, a porous bulk between the surfaces, the bulk comprising first and second regions; the first region comprising a first set of pores having outer rims, and having controlled pore size, and a second set of pores connecting the outer rims of the first set of pores, the second set of pores having a controlled pore size, and a polymer matrix supporting the first set of pores; the second region comprising a third set of pores having outer rims, and having a controlled pore size, and a fourth set of pores connecting the outer rims of the third set of pores, the fourth set of pores having a controlled pore size, and a polymer matrix supporting the third set of pores; and methods of making and using the membranes, are disclosed.

The present invention provides an intrinsically anti-microbial hollow fiber membrane for filtration of liquids. The membrane comprises a plurality of porous hollow bilayer membrane fibers wherein the liquid enters from outside of the fiber, passing through the porous membrane into the lumen of the fiber and coming out from the hollow ending of the fiber, wherein this configuration provides a liquid outside-in arrangement and retains the filtrate outside. It means that membrane of the invention has built in characteristics to act against microbes in order to provide the use with a safe liquid free from microbes. The outer side or outer wall of the hollow fibers may be configured to become hydrophobic whereas inner side or inner wall of the hollow fiber membrane may be configured to become hydrophilic to enhance the water permeability to a great extent. The hollow fiber membrane may be configured to give it an intrinsic anti-microbial capability. A device containing above said membrane has also been disclosed.

The disclosed technology relates to hollow fiber membranes prepared from a dope solution containing a polymer of vinyl chloride, such as chlorinated polyvinyl chloride, and a thermoplastic polyurethane.

The present invention relates to a fibre for purification of liquids comprising a matrix of polymer with organosilane impregnated therein and a method for preparing the same. The fibre of the present invention is capable of providing at least 2 log reduction of viruses, bacteria and cysts and flux of 10 to 1000 litre per square meter per hour at 2 psig.

Provided is a nanofiltration composite membrane, comprising: a supporting layer comprising a polyethylene terephthalate, a polymeric porous layer formed on the supporting layer, the polymeric porous layer comprising a polysulfone and an amphiphilic polymer represented by the formula below:

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and an interfacial polymerization layer formed on the polymeric porous layer and the interfacial polymerization layer comprising polyamide which is synthesized by polymerizing piperazine with 1,3,5-benzenetricarbonyl trichloride; wherein, n1, n2, n3, x, and y are integers greater than 0, the molecular weight of the amphiphilic polymer ranges from 90,000 to 200,000, and a weight ratio of the polysulfone to the amphiphilic polymer ranges from 2 to 20. The nanofiltration composite membrane can increase the removal rate of divalent ions and separate substances of specific molecular weights in solutions.

The present invention provides a porous membrane for water treatment, comprising: a high molecular weight polyethylene, a water-soluble polymer and an antioxidant, the high molecular weight polyethylene having an average molecular weight of 1.0×10.sup.5 to 10.0×10.sup.6 and a density of 0.940 to 0.976 g/cm.sup.3; wherein, the weight of the water-soluble polymer is 5 to 50 parts, the weight of the antioxidant is 0.1 to 10 parts, based on 100 parts of the weight of the high molecular weight polyethylene. The porous membrane for water treatment prepared by the present invention has a thickness of 5 to 30 μm, a pore size of 10 to 100 nm, a porosity of 20 to 60%, and a surface contact angle of 30° to 95°. The porous membrane according to the present invention has good durability, simple preparation process, and relatively thin thickness, a uniform pore size distribution and small pore size, good hydrophilicity, as well as good filtration and adsorption effect.