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Microstructure of HTPB‐based polyurethane membranes and explanation of their low O 2 /N 2 selectivity
Author(s) -
Ruaan RuohChyu,
Ma WenChung,
Chen ShihHsiung,
Lai JuinYih
Publication year - 2001
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1965
Subject(s) - selectivity , microstructure , membrane , solubility , polybutadiene , polyurethane , materials science , chemical engineering , oxygen , polymer chemistry , hydrogen , permeability (electromagnetism) , nitrogen , hydrogen bond , oxygen permeability , chemistry , polymer , organic chemistry , composite material , molecule , copolymer , biochemistry , engineering , catalysis
Polyurethane (PU) membranes usually have high gas permeability but low selectivity. It was supposed that an increase of the hard‐segment content in PU membranes would enhance the selectivity since the hard segment has a higher oxygen affinity and could reduce the chain mobility. However, an attempt to increase the O 2 /N 2 selectivity by increasing the hard‐segment content failed. It was found that increase of the hard‐segment content did increase the gas solubility but the solubility ratio of oxygen to nitrogen was not increased. Increase of the hard‐segment content also reduced the permeabilities of both oxygen and nitrogen, but no improvement of the O 2 /N 2 diffusivity ratio was observed. The microstructure of polybutadiene‐containing PU was examined by DSC and FTIR measurements. It was found that hydrogen bonding between hard segments was the cause of the failure of selectivity improvement. Avoiding the formation of hydrogen bonds between the hard segments is the key for a successful improvement of the O 2 /N 2 selectivity of the PU membranes. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1307–1314, 2001