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Separation membranes and process for preparing the same

  • US 4,948,400 A
  • Filed: 06/28/1989
  • Issued: 08/14/1990
  • Est. Priority Date: 06/30/1988
  • Status: Expired due to Term
First Claim
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1. Polyimide-based separation membranes made from polyimides having repeating units of the general formulas (A) and (B) ##STR12## wherein Ar1 and Ar3 are tetravalent aromatic radicals containing at least one aromatic ring, Ar2 is a divalent aromatic radical containig at least one aromatic ring, R1 and R2 are divalent organic radicals, R3 to R6 are monovalent hydrocarbon radicals, and n is an integer from 1 to 50 with the mole ratio of (A) to (B) falling in the range of 5/95 to 95/5.

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