摘要 |
<p>Pores that are smaller than or larger than a predetermined range of pore sizes in a porous membrane barrier are blocked with a controlled porosity blocking agent. The pores are first filled with a liquid so as to remove any air therein and then subjected to a transmembrane gas blow at a pressure which will clear the larger pores of the liquid. The larger gas filled pores or the smaller liquid filled pores are then blocked by a blocking agent using a polymer-forming chemical reaction, a precipitate-forming chemical reaction or the physical deposition of solids.</p> |