| 摘要 |
The subject of this invention is a novel polymeric composition useful in membrane technology such as microfiltration, nanofiltration, ultrafiltration, reverse osmosis and gas separation. The composition is formed by taking a known condensation polymer such as polyether sulfone, polysulfone or a polyarylether sulfone and modifying it to change the molecular weight distribution. The useful polymers of the invention will have an unmodified number average molecular weight of about 63,000 or less and weight fraction of molecules with a molecular weight of 50,000 or less in the range of 30 to 35%. Utilizing fractional precipitation or other known techniques for concentrating a high molecular weight fraction of a polymer the polymers are modified to have a number average molecular weight of a least 59,000 or a weight fraction of molecules with a molecular weight of 50,000 or less of not more than 19%. Superior resistance to cracking and other forms of membrane degradation results from using the polymer compositions of the present invention in filtration applications.
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