Premium
Polymer networks derived from the anhydride curing of tetraepoxides
Author(s) -
Corcuera M. A.,
Mondragon I.,
Riccardi C. C.,
Williams R. J. J.
Publication year - 1997
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/(sici)1097-4628(19970404)64:1<157::aid-app14>3.0.co;2-1
Subject(s) - epoxy , differential scanning calorimetry , fourier transform infrared spectroscopy , stoichiometry , curing (chemistry) , chemistry , acetic anhydride , monomer , polymer chemistry , acid anhydride , polymer , nuclear chemistry , materials science , catalysis , organic chemistry , chemical engineering , physics , engineering , thermodynamics
Abstract The cure of a technical‐grade TGDDM ( N,N,N′N′ ‐tetraglycidyl‐4,4′‐diaminodiphenylmethane) with two different anhydride hardeners (hexahydrophthalic anhydride [HHPA] and tetrahydrophthalic anhydride [THPA]) is reported. The reaction was followed by differential scanning calorimetry (DSC), in situ infrared spectroscopy (FTIR), and viscosity measurements at constant temperature. Onset values of the glass transition temperatures of fully reacted networks under stoichiometric conditions were 206°C with HHPA and 184°C with THPA. THPA was more reactive than was HHPA but it was necessary to heat the mixture above its melting point to generate a homogeneous solution (HHPA remained in solution at room temperature). A first‐order kinetics was observed after an induction period necessary to establish a pseudo‐steady‐state concentration of OH and COOH groups. A catalytic effect of the KBr used in the FTIR measurements was found, in agreement with other authors. Formulations containing an epoxy excess exhibited a higher reactivity due to the increase in the hydroxyl concentration introduced by the epoxy monomer. An increase in the heat of reaction expressed per anhydride equivalent was ascribed to the presence of the epoxy homopolymerization as a side reaction. It was estimated that about 38% of excess epoxy groups over the anhydride groups are homopolymerized in the case of HHPA and 17% in the case of THPA. Full conversions of both epoxy and anhydride groups are obtained for formulations with stoichiometric ratios, r (anhydride/epoxy groups) = 0.72 in the case of HHPA and 0.85 in the case of THPA. These values are in the range where the maximum glass transition temperature has been reported for epoxy‐anhydride formulations. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 157–166, 1997