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The cure reactions, network structure, and mechanical response of diaminodiphenyl sulfone‐cured tetraglycidyl 4,4′diaminodiphenyl methane epoxies
Author(s) -
Morgan Roger J.,
Mones Eleno T.
Publication year - 1987
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.1987.070330401
Subject(s) - epoxide , sulfone , fourier transform infrared spectroscopy , chemistry , polymer chemistry , ether , amine gas treating , catalysis , reaction mechanism , materials science , organic chemistry , chemical engineering , engineering
Abstract The cure reactions, chemical structure, and network topography of diaminodiphenyl sulfone (DDS)‐cured tetraglycidyl 4,4′diaminodiphenyl methane (TGDDM) epoxies are reported. Systematic Fourier transform infrared (FTIR) spectroscopy studies of the cure and degradation reactions of TGDDM‐DDS epoxies in the 100–300°C temperature range as a function of DDS and boron trifluoride monoethylamine, BF 3 : NH 2 C 2 H 5 catalyst concentrations are presented. FTIR studies indicate TGDDM epoxide homopolymerizes in the 175–250°C range via epoxide‐hydroxyl (E‐OH) chain extension reactions. The hydroxyl groups are initially present as α‐glycol impurities or are formed by epoxide isomerization and/or oxidation. Three principal cure reactions occur at 177°C for TGDDM‐DDS epoxies, namely primary amine‐epoxide (PA‐E), secondary amine‐epoxide (SA‐E) and E‐OH reaction with the PA‐E reaction being an order of magnitude faster than the other two cure reactions. The PA‐E reaction dominates the early stages of cure and, hence, composite processing conditions. The three cure reactions are catalyzed to similar extents by BF 3 : NH 2 C 2 H 5 . FTIR and molecular modeling studies indicate that the E‐OH and SA‐E reactions can occur intermolecularly to form crosslinks or intramolecularly to form non‐cross‐linked internal rings. The complex degradation reactions of TGDDM‐DDS epoxies in the 177–300°C range are reported. The principal degradation reactions involve (1) dehydration and/or oxidation to form ether crosslinks and (2) decomposition of the EOH cure reaction products to form propenal. Based on a knowledge of the cure reactions, together with molecular modeling, the chemical structure and network topography of TGDDM‐DDS epoxies are reported.