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Hydrolysis and other phenomena affecting structure and performance of polyamide 6 membrane
Author(s) -
Yao C. W.,
Burford R. P.,
Fane A. G.,
Fell C. J. D.,
McDonogh R. M.
Publication year - 1987
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.1987.070340706
Subject(s) - polyamide , membrane , protonation , hydrolysis , viscometer , dissolution , polymer , polymer chemistry , chemistry , chemical engineering , flux (metallurgy) , materials science , viscosity , organic chemistry , ion , composite material , biochemistry , engineering
The rate of hydrolysis of polyamide 6 in membrane casting solution containing strong mineral acid has been studied by determining changes in molecular weight, as estimated from dilute solution viscometry measurements. Hydrolysis is shown to be first order with a long half‐life of about 250 days. A two‐step dissolution process for polyamide 6 is proposed. The effect of extended dope maturation time upon polyamide 6 membrane preparation and performance has been examined. At short maturation times where protonation of polymer chain is occurring, flux is relatively low. A major increase in flux occurs after about 10 h, when protonation appear complete and hydrolysis has begun. Hydrolysis reduces polymer chain entanglement, and so quite different mechanisms for membrane formation exist as dope maturation time proceeds. With chains less than the critical entanglement length, nodular top layer membranes and alveolar walls lead to high water flux. However, such membranes are quite fragile.