Disclosed are a method of manufacturing a polyethylene membrane comprising: stretching a polyethylene film in a first direction during a first stretching; attaching a plurality of rods on side edges of the polyethylene film; attaching a tape on the polyethylene film; stretching the polyethylene film having the rods attached thereto in a second direction during a second stretching; and annealing the polyethylene film after the second stretching. The second direction can be a transverse direction of the first direction, and the first stretching and the second stretching can be performed at the same (or higher) temperature and the same stretching speed as each other.

A preparation method of separation membrane is provided. First, a polyimide composition including a dissolvable polyimide, a crosslinking agent, and a solvent is provided. The dissolvable polyimide is represented by formula 1: ##STR00001## wherein B is a tetravalent organic group derived from a tetracarboxylic dianhydride containing aromatic group, A is a divalent organic group derived from a diamine containing aromatic group, A is a divalent organic group derived from a diamine containing aromatic group and carboxylic acid group, and 0.1X0.9. The crosslinking agent is an aziridine crosslinking agent, an isocyanate crosslinking agent, an epoxy crosslinking agent, a diamine crosslinking agent, or a triamine crosslinking agent. A crosslinking process is performed on the polyimide composition. The polyimide composition which has been subjected to the crosslinking process is coated on a substrate to form a polyimide membrane. A dry phase inversion process is performed on the polyimide membrane.

Provided is a gas separation membrane containing polysaccharides and being characterized by having a crystallinity of 17% or lower, the crystallinity being represented by equation (1) below: (1) Crystallinity (%)=[I.sub.c/(I.sub.c+I.sub.a)]100 (In equation (1), I.sub.c is the sum of the integrals of the scattering intensities of crystalline peaks obtained from X-ray diffraction analysis of the gas separation membrane, and I.sub.a is the sum of the integrals of the scattering intensities of the amorphous halo).

The present invention provides a method for preparing a porous membrane of a fluorine-based resin having an improved shrinkage while maintaining excellent filtration efficiency and air permeability.

The present invention relates to the technical field of filtering materials and provides a reverse osmosis membrane support material. The support material is obtained by hot pressing treatment of a surface layer, a middle layer and a bottom layer which are sequentially disposed from top to bottom. The surface layer and the bottom layer are each a spunbond non-woven fabric layer made of thermoplastic polymer spunbonded fibers, and the middle layer is a polymer nanofiber membrane. In accordance with the invention, the comprehensive mechanical strength of the reverse osmosis membrane support material is improved, and the overall anti-leakage performance is enhanced. A spunbond technology and a nanofiber preparation technology are combined organically, and the method is simple and controllable. The support material can be produced in batches.

The invention relates to a method for preparing a MeAPO-18 supported membrane comprising a MeAPO-18 crystal layer on a porous support, wherein the obtained MeAPO-18 supported membrane as a lamellar crystal morphology. The invention is also directed to the said membranes and to their use.

Disclosed herein are asymmetric thin-film composite membranes and methods of making and using the same. Also included herein are asymmetric thin-film composite membranes for preventing and/or reducing microfouling or macrofouling. Additionally included herein are asymmetric thin-film composite membranes for preventing and/or reducing biofilm.

A method of making a hollow fiber carbon molecular sieve is comprised of heating a hollow polymer fiber to a carbonization temperature in an atmosphere that is non-oxidizing to form a hollow fiber carbon molecular sieve, wherein during at least a portion of the heating a tensile force is applied to the hollow polymer fiber. The method may improve the separation of gases similar in size such a propylene from propane.

A hydrophilic graphitic material is provided that may be formed by heating a graphitic material to a temperature between about 150 C. to about 1400 C. for an extended period of time under an inert atmosphere. Annealing CNT film at 500 to 1400 removes amorphous carbon to produce purified CNT film. The purified CNT film can be further densified with the treatment of alkylphosphonic acid or alkyldiphophonic acid and heating to produce a hydrophilic, densified CNT film which is mechanically robust and does not adhere to other solid surfaces. These films can be used as filtration membranes with superior membrane fouling resistance among other uses.

A preparation method of separation membrane is provided. First, a polyimide composition including a dissolvable polyimide, a crosslinking agent and a solvent is provided. The dissolvable polyimide is represented by formula 1:

##STR00001##

wherein B is a tetravalent organic group derived from a tetracarboxylic dianhydride containing aromatic group, A is a divalent organic group derived from a diamine containing aromatic group, A is a divalent organic group derived from a diamine containing aromatic group and carboxylic acid group, and 0.1X0.9. The crosslinking agent is an aziridine crosslinking agent, an isocyanate crosslinking agent, an epoxy crosslinking agent, a diamine crosslinking agent, or a triamine crosslinking agent. A crosslinking process is performed on the polyimide composition. The polyimide composition which has been subjected to the crosslinking process is coated on a substrate to form a polyimide membrane. A wet phase inversion process is performed on the polyimide membrane.