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Spin probe study of semi‐interpenetrating polymer networks based on polyurethane and polymethacrylate functional prepolymers
Author(s) -
Čulin Jelena,
Veksli Zorica,
Anžlovar Alojz,
Žigon Majda
Publication year - 2003
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.1202
Subject(s) - polyurethane , electron paramagnetic resonance , polymer , materials science , polymer chemistry , volume fraction , copolymer , functional group , glass transition , spin probe , chemistry , chemical engineering , composite material , nuclear magnetic resonance , physics , engineering
The motional transition and heterogeneity of semi‐interpenetrating networks (SIPNs) based on polyurethane (PU) with carboxylic groups and methacrylic copolymer (PM) with tertiary amine groups were studied by the electron spin resonance (ESR) spin probe method. The concentration of functional groups in both prepolymers varied from 0 to 0.45 mmol g −1 . Spin‐probed SIPNs show that the temperature‐dependent spectra are sensitive to polymer interactions imposed by functional groups. These interactions determine the free volume distribution in the matrix and temperature at which motional transition takes place. The fraction of free volume increases with functional group concentration and reaches its maximum at 0.25 mmol g −1 . Further increases in the functional group concentration reduce the free volume. The results of the networks with strong interactions are discussed in terms of the interference of the plasticizing effect of the PU component and the formation of possible cluster cross‐links, which restricts segmental motions. Copyright © 2003 Society of Chemical Industry