Premium
Citric acid–diethylenetriamine salts as latent curing agents for epoxy resins
Author(s) -
Galego N.,
Vazquez A.,
Riccardi C. C.,
Williams R. J. J.
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.1992.070450407
Subject(s) - diethylenetriamine , epoxy , curing (chemistry) , stoichiometry , bisphenol a , nuclear chemistry , endothermic process , thermal decomposition , citric acid , chemistry , polymer chemistry , thermosetting polymer , exothermic reaction , materials science , organic chemistry , adsorption
Citric acid (CA)–diethylenetriamine (DETA) salts (CADETA) were prepared by using a 4.5 : 1 molar ratio of DETA–CA and removing the DETA excess. The structure of CADETA was analyzed by 13 C‐NMR, IR, and DSC associated with weight loss. One‐step formulations consisted on dispersions of CADETA (variable amounts) in an epoxy resin based on diglycidylether of bisphenol A (DGEBA, EEW = 185.5 g/eq). The cure was followed in the pressure cell of a DSC ( N 2 at 2.5 MPa), to avoid volatilization of DETA in the temperature range where decomposition of CADETA and beginning of reaction took place ( T > 175°C). A very small heat of reaction was observed, (−Δ H ) ∼ 10 kJ/eq, resulting from the simultaneous endothermic salt decomposition and exothermic network formation. A stoichiometric formulation showed a T g = 180°C, i.e., some 60°C higher than the one observed for the usual DGEBA/DETA system.