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Monomer sequence length distributions of hard segments of linear segmented poly(urethane–urea)s 1: chromatographic study
Author(s) -
Hanahata Hiroyuki,
Kamide Kenji
Publication year - 1995
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/pi.1995.210380310
Subject(s) - prepolymer , monomer , sequence (biology) , polymer , polymerization , polymer chemistry , reactivity (psychology) , materials science , urea , ethylenediamine , chemistry , polyurethane , organic chemistry , composite material , medicine , biochemistry , alternative medicine , pathology
An attempt was made to determine, by the chromatographic method, monomer sequence length distributions of the hard segments in segmented poly(urethane–urea)s (PURs) synthesised in a two‐step process: (1) a prepolymer formation reaction of an excess of methylenebis(4‐phenylisocyanate) (MDI) with poly(tetramethyleneoxide) (PTMO) and (2) a polymerisation reaction of the prepolymer containing unreacted MDI with ethylenediamine, giving PUR. The monomer sequence length of the hard segment was found to become longer and its distribution to broaden as the initial concentration ratio of MDI to PTMO increased. This result is attributable to an increase of the concentration ratio of the unreacted MDI to the prepolymer, leading to gelation of the polymer solution. By comparing the chromatographic results with the theoretical data calculated in the simple case of the equal reactivity of the reactants in the prepolymerisation and polymerisation reactions, respectively, the existence of unequal reactivities of the reactants in both reactions, is predicted.