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Thermodynamic characterization of interpenetrating polymer networks
Author(s) -
Privalko Valery P.,
Azarenkov Vassily P.,
Baibak Alexander V.,
Korskanov Valery V.,
Titov Georgy V.,
Frisch Harry L.,
Zhou Peiguang
Publication year - 1996
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.10494
Subject(s) - materials science , polymer , gibbs free energy , phase (matter) , homogeneous , thermodynamics , kinetic energy , glass transition , polymer chemistry , heat capacity , chemical engineering , composite material , organic chemistry , chemistry , physics , quantum mechanics , engineering
Crosslinked poly(methyl methacrylate) (PMMA‐c), poly(carbonate‐urethane) (PCU‐c), poly(vinyl pyridine) (PVP‐c), and full, simultaneous interpenetrating polymer networks (IPNs) based on the above polymers were characterized by precise heat capacity ( C p ) measurements in the temperature interval 4.2–450 K. The raw values of C p scaled with temperature ( T ) as C p ∼ T d with d = 2 and 5/3, as expected for a fracton‐like vibration regime, in the temperature intervals 8–10 and 10–30 K, respectively. A single glass transition temperature ( T g ) and two T g 's were observed for apparently homogeneous and microphase‐separated IPNs, respectively. Judged by the positive sign of the excess Gibbs free energy, the apparently single‐phase state of homogeneous IPNs is thermodynamically unstable; however, its kinetic stability is ensured by permanent topological constraints (network junctions) prohibiting the incipient phase separation.