Asymmetric hollow fiber membranes, membrane contactors, and related production and use methods. The asymmetric hollow fiber membranes include a porous substrate having a multiplicity of pores, the porous substrate including at least a first semi-crystalline thermoplastic polyolefin copolymer derived by polymerizing at most 3 wt. % of linear or branched alpha olefin monomers with at least 97 wt. % of 4-methyl-1-pentene monomer. The asymmetric hollow fiber membranes also include a skin layer overlaying the porous substrate, the skin layer including a second semi-crystalline thermoplastic polyolefin copolymer derived by polymerizing at least 2 wt. % of linear or branched alpha olefin monomers with at most 98 wt. % of 4-methyl-1-pentene monomer. The skin layer is less porous than the porous substrate and forms an outer surface of the asymmetric hollow fiber membrane, while the porous substrate forms an inner surface of the hollow fiber membrane. The skin layer is preferably nonporous.

A catalytic composite is formed of a catalytic layered assembly including a porous catalytic fluoropolymer film and one or more felt batts connected with the porous catalytic fluoropolymer film. At least one felt batt is positioned adjacent the upstream side of the porous catalytic fluoropolymer film to form the catalytic composite. The fluoropolymer film is perforated to allow for enhanced airflow therethrough while retaining the capability of catalyzing the reduction or removal of chemical species in fluid flowing through the catalytic composite.

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.

Hollow fiber membranes, membrane contactors, and related production and use methods. The membranes include a substrate having a multiplicity of pores and a skin layer overlaying the porous substrate. The porous substrate includes a first semi-crystalline thermoplastic polyolefin (co)polymer resin and a nucleating agent in an amount effective to achieve nucleation. The skin layer includes a second semi-crystalline thermoplastic polyolefin (co)polymer resin derived by polymerizing at most 98 wt. % of 4-methyl-1-pentene monomer with at least 2 wt. % of linear or branched alpha olefin monomers. Preferably, the first thermoplastic polyolefin (co)polymer is different from the second thermoplastic polyolefin (co)polymer. The skin layer is less porous than the porous substrate and forms an outer surface of the hollow fiber with the porous substrate forming an inner surface. The hollow fibers are formed by co-extruding the porous substrate resin and the skin layer resin through an annular die.

Described is a polyethylene membrane and in particular an ultra-high molecular weight polyethylene member that provides a high air permeability and is hydrophobic. The membranes have small pores and are suitable for sterilization by exposure to gamma radiation. The membranes can be made by methods that involve one or more of stretching the membrane and grafting hydrophobic monomers onto the membrane surface. A perfluorinated monomer, such as perfluoro-n-octyl acrylate, can be grafted to one or more surfaces of the membrane. The membrane have a high flow rate compared to unstretched or ungrafted membranes.

The present disclosure relates to a micro or nano porous membrane composed of a stretched membrane of a fluororesin membrane, wherein the fluororesin membrane contains sintered bodies of a plurality of core-shell particles containing fluororesins, wherein the core-shell particles include cores and shells covering outer surfaces of the cores, wherein an average particle size of the core-shell particles before being sintered is greater than or equal to 100 nm and less than or equal to 1,000 nm, wherein a ratio of a volume of the shells to a volume of the cores in the core-shell particles before being sintered is greater than or equal to 2/98 and less than or equal to 50/50, wherein a fluororesin of the cores is a tetrafluoroethylene-hexafluoropropylene copolymer, a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer or a combination thereof, and a fluororesin of the shells is polytetrafluoroethylene, and wherein a first heat of fusion of the fluororesins in the core-shell particles is less than or equal to 68 J/g.

A catalytic composite is formed of a catalytic layered assembly including a porous catalytic fluoropolymer film and one or more felt batts connected with the porous catalytic fluoropolymer film. At least one felt batt is positioned adjacent the upstream side of the porous catalytic fluoropolymer film to form the catalytic composite. The fluoropolymer film is perforated to allow for enhanced airflow therethrough while retaining the capability of catalyzing the reduction or removal of chemical species in fluid flowing through the catalytic composite.

A perfluorocarbon-free membrane composed of a non-perfluorocarbon material having a first side and a second side opposite of the first side. The perfluorocarbon-free membrane also includes a plurality of pores, each having an inlet and outlet and each passing through the non-perfluorocarbon material so that each pore provides fluidic communication between the first and second sides of the non-perfluorocarbon material. A portion of the non-perfluorocarbon material extends over the inlet and outlet of each the plurality of pores so that a cross-sectional area of the inlets and outlets in a direction of the extension of the non-perfluorocarbon material is smaller than a cross-sectional area of the respective pore in the direction of the extension of the non-perfluorocarbon material. The perfluorocarbon-free membrane does not include a hydrophobic perfluorocarbon coating.

The present disclosure provides a fluorine-based resin porous membrane exhibiting high mechanical strength and low heat shrinkage rate while having a fine pore size, and a method for preparing the same.

Described is a polyethylene membrane and in particular an ultra-high molecular weight polyethylene member that provides a high air permeability and is hydrophobic. The membranes have small pores and are suitable for sterilization by exposure to gamma radiation. The membranes can be made by methods that involve one or more of stretching the membrane and grafting hydrophobic monomers onto the membrane surface. A perfluorinated monomer, such as perfluoro-n-octyl acrylate, can be grafted to one or more surfaces of the membrane. The membrane have a high flow rate compared to unstretched or ungrafted membranes.