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Method for making semi-permeable polymer membranes

  • US 5,275,766 A
  • Filed: 10/30/1992
  • Issued: 01/04/1994
  • Est. Priority Date: 10/30/1992
  • Status: Expired due to Term
First Claim
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1. A method for making a semi-permeable microporous polymer sheet having an intercommunicating pore structure which comprises the steps of blending a batch mixture of a thermoplastic polymer and a finely divided leachable glass to form a two-phase glass-polymer blend material, extruding the glass-polymer blend material through a die to form a sheet having a sheet surface and comprising a continuous polymer network and an intercommunicating glass phase, and thereafter leaching the intercommunicating glass phase from the sheet without disruption of the polymer network, wherein:

  • prior to or subsequent to leaching, the sheet surface is exposed to a plasma of an energy at least sufficient to etch thermoplastic polymer from the sheet surface, for a time at least sufficient to increase the area of leachable glass or intercommunicating pore structure exposed at the sheet surface, thus to provide a microporous polymer sheet having an intercommunicating pore structure.

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