Abstract: A tubesheet is formed at the end of a module containing polymeric material for gas separation, by immersing the end of the module in an epoxy material, or its equivalent. A vacuum, or partial vacuum, applied at or near the opposite end of the module, tends to draw the epoxy material towards the source of the vacuum, and results in a tubesheet having a desired thickness, even though the epoxy material may have relatively high viscosity. The method produces effective tubesheets, while minimizing the degree to which the tubesheet covers the otherwise useful surface area of the polymeric material. The method thus produces gas-separation modules having enhanced productivity.

Abstract: An air dehydration membrane is made of a hydrophilic polymer having a permeability for water vapor which is greater than its permeability for air, and having low selectivity between oxygen and nitrogen. The membrane has a hydrophilic coating, which itself may be a polymer. The coating does not affect the selectivity of the coated membrane with respect to oxygen and nitrogen, but does increase selectivity of the membrane with respect to water vapor. A preferred material for the membrane is polysulfone. Preferred materials for the coating are poly vinyl alcohol and Triton X-100. The membrane is selected such that the dominant mechanism for gas flow through the membrane is Knudsen flow. The membranes are made at low cost, and can outperform existing commercial membranes in either volumetric productivity or product recovery.

Abstract: A surface modified gas separation membrane having improved permselective properties for separating a mixture of gases as compared to the unmodified membrane, is described. The gas separation membrane is made by a process comprising the steps of coating a surface unmodified gas separation membrane with a solution of a coating material, wherein the coating material is an organic material having at least one site of unsaturation; heating the coated gas separation membrane; and contacting the heated coated gas separation membrane with at least one oxidizing agent for a time effective to surface modify the gas separation membrane to produce the surface modified gas separation membrane having improved permselectivity.

Abstract: A method for preparing a surface modified gas separation membrane, wherein said membrane has improved permselective properties for separating a mixture of gases as compared to the unmodified membrane, is described. The method comprises coating a surface unmodified gas separation membrane with a solution of a coating material, wherein the coating material is an organic material having at least one site of unsaturation; heating the coated gas separation membrane; and contacting the heated coated gas separation membrane with at least one oxidizing agent for a time effective to surface modify the gas separation membrane to produce the surface modified gas separation membrane having improved permselectivity.

Abstract: Hollow fiber membrane modules are manufactured by weaving hollow fiber membranes into a web while the fibers still contain a residual amount of the organic liquids used in the extrusion of the fibers. The web once formed is then passed through a final solvent extraction stage, followed by drying and heating to fix the final form and permeation characteristics of the membranes, and finally rolling the web into a bundle which forms the interior of the module. The hollow fibers are woven as fill in the web.

Abstract: The invention is a semi-permeable hollow fiber gas separation membrane possessing a non-external discriminating region fabricated from hydrophobic polymeric materials possessing less than about 1 weight percent equilibrium water content at about 25.degree. C. The invention includes a process for making such membranes as well as a method of using such membranes.

Abstract: The invention is a process for the preparation of a POWADIR membrane comprising bisphenol-based polycarbonates wherein at least 25 percent by weight of the bisphenol moieties are tetrahalogenated wherein the halogen is Cl or Br, and the membrane prepared by such process.

Abstract: An improved process for recovery of ethylene from a polymerization process is described. A normally solid membrane is employed to recover an ethylene enriched gas stream from the polymerization vent gases. The ethylene enriched gas stream is recycled to the polymerization process.