CPC B01D 53/228 (2013.01) [B01D 67/0025 (2013.01); B01D 69/02 (2013.01); B01D 69/088 (2013.01); B01D 71/262 (2022.08); B01D 71/76 (2013.01); B01D 67/0083 (2013.01); B01D 2256/10 (2013.01); B01D 2256/245 (2013.01); B01D 2257/104 (2013.01); B01D 2257/504 (2013.01); B01D 2325/023 (2013.01); B01D 2325/027 (2013.01); B01D 2325/04 (2013.01)] | 20 Claims |
1. An asymmetric hollow fiber membrane comprising:
a porous substrate having a plurality of pores, wherein the porous substrate includes a first semi-crystalline thermoplastic polyolefin copolymer derived by polymerizing at most 3 wt. % of linear or branched alpha olefin monomers with from at least 97 wt. % of 4-methyl-1-pentene monomer; and
a skin layer overlaying the porous substrate, wherein the skin layer includes a second semi-crystalline thermoplastic polyolefin copolymer derived by polymerizing at least 2 wt. % of linear or branched alpha olefin monomers, with at most 98 wt. % of 4-methyl-1-pentene monomer, optionally wherein the linear or branched alpha olefin monomers are selected from the group consisting of ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, isobutylene, vinylcyclohexane, 3-ethyl-1-pentene, 1,3-methyl-1-pentene, cyclobutene, cyclopentane, 2-norbornene, 3-methyl-2-norbornene, 5-methyl-2-norbornene, tetracyclododecene, methyltetracyclododecene, dimethyltetracyclododecene 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-eicosene, or a combination thereof;
wherein the amount of 4-methyl-1-pentene monomer used in the first semi-crystalline thermoplastic polyolefin copolymer differs from the amount of 4-methyl-1-pentene monomer used in the second semi-crystalline thermoplastic polyolefin copolymer by at least 1 wt. %.
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