A polyolefin multilayer microporous membrane includes at least first microporous layers which form both surface layers of the membrane and at least a second microporous layer disposed between the both surface layers, wherein static friction coefficient of one of the surface layers of the polyolefin multilayer microporous membrane against another surface layer in a longitudinal direction (MD) is 1.1 or less, and wherein pore density calculated from an average pore radius measured by mercury porosimetry method and porosity, according to Formula (1) is 4 or more:
Pore density=(P/A.sup.3)×10.sup.4  (1)
wherein A represents the average pore radius (nm) measured by mercury porosimetry method and P represents the porosity (%).

The invention provides a method of forming a membrane between a first volume of polar medium and a second volume of polar medium. In some embodiments, the method involves providing a first volume including polar medium and a second volume including polar medium which are separated from one another by an apolar medium, in which at least one of the first and second volumes has a layer including amphipathic molecules.

The invention provides a method of forming a membrane between a first volume of polar medium and a second volume of polar medium. In some embodiments, the method involves providing a first volume including polar medium and a second volume including polar medium which are separated from one another by an apolar medium, in which at least one of the first and second volumes has a layer including amphipathic molecules.

Provided herein are tubular membrane filter elements, tangential flow filtration systems comprising such filter elements and methods of using such filter elements and filtration systems.

The invention provides mixed matrix membranes (MMMs) for olefin/paraffin separation and methodes of making and using the same. The MMMs comprise a continuous polymer matrix with metal doped zeolite nano-particles. A separation technology based upon the composite membranes is effective for propylene and other olefin separation from olefin/paraffin mixtures, and the separation is more energy-efficient than the conventional cryogenic technique.

The invention provides mixed matrix membranes (MMMs) for olefin/paraffin separation and methodes of making and using the same. The MMMs comprise a continuous polymer matrix with metal doped zeolite nano-particles. A separation technology based upon the composite membranes is effective for propylene and other olefin separation from olefin/paraffin mixtures, and the separation is more energy-efficient than the conventional cryogenic technique.

A porous membrane is made from a poly(phenylene ether) copolymer containing 10 to 40 mole percent repeat units derived from 2-methyl-6-phenylphenol and 60 to 90 mole percent repeat units derived from 2,6-dimethylphenol; and a block copolymer containing backbone or pendant blocks of poly(C.sub.2-4 alkylene oxide). The porous membrane is made by dissolving the poly(phenylene ether) copolymer in a water-miscible polar aprotic solvent to form a membrane-forming composition; and phase-inverting the membrane forming-composition in a first non-solvent composition to form the porous membrane. A method of making a hollow fiber by coextrusion through a spinneret having an annulus and a bore, includes coextruding the membrane-forming composition through the annulus, and a first non-solvent composition through the bore, into a second non-solvent composition to form the hollow fiber.

A porous membrane is made from a poly(phenylene ether) copolymer containing 10 to 40 mole percent repeat units derived from 2-methyl-6-phenylphenol and 60 to 90 mole percent repeat units derived from 2,6-dimethylphenol; and a block copolymer containing backbone or pendant blocks of poly(C.sub.2-4 alkylene oxide). The porous membrane is made by dissolving the poly(phenylene ether) copolymer in a water-miscible polar aprotic solvent to form a membrane-forming composition; and phase-inverting the membrane forming-composition in a first non-solvent composition to form the porous membrane. A method of making a hollow fiber by coextrusion through a spinneret having an annulus and a bore, includes coextruding the membrane-forming composition through the annulus, and a first non-solvent composition through the bore, into a second non-solvent composition to form the hollow fiber.

The present invention discloses a centrifuge filtration tube comprising a centrifuge tube (2) and a centrifuge tube (1) housed in the centrifuge tube (2). One or more constant-volume vents (7) and multiple pores (4) are provided on a sidewall of the centrifuge tube (1). The one or more constant-volume vents (7) are located above the pores (4). The pores (4) are covered with a filtering membrane (3). The disclosed centrifuge filtration tube has the advantages of being simple, easy to use, highly efficient, and inexpensive, which can save large amounts of labor and time in analyses of large number of samples.

The present invention discloses a centrifuge filtration tube comprising a centrifuge tube (2) and a centrifuge tube (1) housed in the centrifuge tube (2). One or more constant-volume vents (7) and multiple pores (4) are provided on a sidewall of the centrifuge tube (1). The one or more constant-volume vents (7) are located above the pores (4). The pores (4) are covered with a filtering membrane (3). The disclosed centrifuge filtration tube has the advantages of being simple, easy to use, highly efficient, and inexpensive, which can save large amounts of labor and time in analyses of large number of samples.