Membrane
UBE's polyimide membrane is produced by the condensation polymerizationof biphenyltetracarboxylic dianhydride and aromatic diamines. Itschemical formula is:

Ar shows divalent aromatic radical
The polyimide membanes are a type of hollow fiber with an asymmetricstructure as illustrated.

The dense layer serves to separate a gas mixture and is designedto be ultrathin in order to obtain a practical permeation rate.The microporous support of the membrane only reinforces the surfacedense layer and hardly affects gas separation. The hollow fibermembrane is uniformly manufactured in one-step process from thepolyimide dope and is wholly made of the same material.

Gas Separation by Membrane
Viewing polymeric materials magnified enough to be seen molecularlevel, it can be observed that there exists the space between molecules,along which gases can pass through. Accordingly, when gases, foundin both high and low partial pressure side, are existent separatedwith a pinhole-free polymer membrane, gases move from the high partialpressure side to the low partial pressure side due to the differentialpressure.

Our own gas separation-oriented membranes have permeability ofvarious gases as shown in the example data.

Compared with other gases, H20, H2, He and C02 enjoy a high permeability,which is why we can expect efficient separation of such permeablegases from mixed gases.

Module Configuration
UBE's polyimide membranes are all hollow fibers and the fiber bundleis compactly packed in a pressure vessel. A concept for UBE GASSEPARATOR; the membrane module for a separation of H2 or He, isshown. When a feed gas mixture is introduced into the Separatorkeeping the pressure of the permeate side lower than that of thefeed gas side, the permeable components in the feed gas pass throughthe membrane from the outer side to the inside of the hollow fiber.