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Curing behavior of epoxy resin having hydroxymethyl group and different molecular weight distribution
Author(s) -
Ohtsuka K.,
Hasegawa K.,
Fukuda A.,
Uede K.
Publication year - 1992
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.1992.070440906
Subject(s) - epoxy , curing (chemistry) , hydroxymethyl , materials science , glass transition , differential scanning calorimetry , molar mass distribution , composite material , activation energy , polymer chemistry , chemistry , polymer , organic chemistry , physics , thermodynamics
o ‐Cresol novolac‐type epoxy resins having hydroxymethyl group were synthesized. These epoxy resins were cured with a mixture of 4,4′‐diaminodiphenylmethane and m ‐phenylenediamine (molar ratio, 6:4) as a hardener. Effects of molecular weight distribution of epoxy resins on curing behavior were studied. Curing behavior of epoxy resins with hardener were examined by differential scanning calorimetery (DSC), and cure reaction parameters were obtained. Viscoelastic properties of the cured epoxy resins were studied by dynamic mechanical analyzer. It was found that the lower the average molecular weight of the epoxy resin, that is, the higher the concentration of hydroxymethyl group, the shorter the onset time of exothermal reaction, the higher the rate constant ( k ), and the lower the activation energy ( E a ) were. It was also found that glass transition temperature ( T g ) of fully cured epoxy resins was higher than those of fully cured general novolac‐type epoxy resins.