A hollow fiber membrane and a method of preparing the same. The hollow fiber membrane has an inner surface and an outer surface, wherein the inner surface has a zebra-stripe pattern in which a dense portion and a porous portion are alternately formed in a longitudinal direction of the hollow fiber membrane.

Solution comprising a sulfone polymer, a water-soluble polymer and a N-acyl-morpholine of formula I wherein R.sup.1 is a hydrogen atom or a C1- to C3 alkyl group.

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Provided is a porous hollow fiber membrane made of a thermoplastic resin, wherein a membrane thickness is 0.050 mm or larger and 0.25 mm or smaller, and when a strength coefficient is defined as K=(compressive strength)/((membrane thickness)/(inside diameter/2)).sup.3, K=1.7 or more.

The present invention is directed towards a method for the preparation of macroporous or mesoporous polymer films in hollow fiber geometry. The method according to the present invention reliably produces macroporous or mesoporous homopolymer or copolymer films in hollow fiber geometry having an ordered porous structure. Preferably, the pores are isoporous. The method involves the purging or casting a polyol adjacent to a film forming polymer solution of at least one homopolymer or at least one copolymer in a suitable solvent while polyol diffuses in and then condenses out of the film forming solution before the solution is immersed into a coagulation bath. The methods also require the presence of a carrier solution or carrier substrate during spinning or casting. The method makes macroporous or mesoporous film formation possible with a single step processing method.

An method of making a porous asymmetric membrane involves dissolving a poly(phenylene ether), poly(phenylene ether) copolymer, polyethersulfone, polysulfone, polyphenylsulfone, polyimide, polyetherimide, polyvinylidene fluoride, or a combination thereof in a water-miscible polar aprotic solvent to provide a membrane-forming composition; and phase-inverting the membrane-forming composition in a first non-solvent composition composed of water, a water-miscible polar aprotic solvent, or a mixture thereof, and a polymer additive dissolved in the first non-solvent composition. The method can be a method of making a hollow fiber by coextrusion through a spinneret having an annulus and a bore, including coextruding the membrane-forming composition through the annulus, and the first non-solvent composition through the bore, into a second non-solvent composition composed of water, a water-miscible polar aprotic solvent, or a mixture thereof to form the hollow fiber.

Provided are: a porous polyether sulfone film having macrovoids and having excellent dimensional stability; and a production method therefor. Provided is a porous polyether sulfone film having a surface layer (a), a surface layer (b), and a macrovoid layer interposed between the surface layer (a) and the surface layer (b). The macrovoid layer has a partition wall joined to the surface layers (a) and (b) and a plurality of macrovoids surrounded by the partition wall and the surface layers (a) and (b). The surface layer (a) and the surface layer (b) have pores connected to the macrovoids.

Provided is a vinylidene fluoride porous hollow fiber membrane excellent in fouling resistance due to reduced organic substance absorbance, preferably having preferable pore structures to enable to have high permeability, high fractionation performance, and good process controllability. The membrane includes a vinylidene fluoride resin and 0.5 to 10% by weight of a hydrophilic resin, having a ratio Pi/Po of 2.5 to 50 where Pi and Po denote an average pore size on inner surface and an average pore size on outer surface, respectively, and having a pure water permeation rate satisfying the following formula:
(FLUX.sub.d/FLUX.sub.w)10040.0 wherein FLUX.sub.d represents a pure water permeation rate (L/m.sup.2/hr/98 kPa) of the hollow fiber membrane in a dry state, and FLUX.sub.w represents a pure water permeation rate (L/m.sup.2/hr/98 kPa) of the hollow fiber membrane in a wet state.

The present invention relates to a porous membrane, process for the manufacture thereof and uses thereof.

The present invention relates to a composite porous hollow-fiber membrane including a first layer and a second layer which each include a fluororesin-based polymer, in which the first layer has a columnar texture oriented in a longitudinal direction of the composite porous hollow-fiber membrane, the columnar texture has an average value v of a Raman orientation parameter calculated with the specific formula, and the second layer has a three-dimensional network texture and has an average surface-pore diameter of 5.0 nm to 5.0 m.

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.