New epoxy resins. II. The preparation, characterization, and curing of epoxy resins and their copolymers

Abstract

SynopsisA polymer having high aromaticity andor cyclic ring structures in the chain backbone usually gives high heat resistance and flame resistance. Five glycidyl ether-type epoxy resins are prepared from bisphenol A (DGEBA), 9.9-bis(4-hydroxypheny1)fluorene (DGEBF), 3,6-dihydroxyspiro-[fluorene-9,9'-xanthane] (DGEFX), lO,lO-bis(4-hydroxyphenyl)anthrone (DGEA), and 9,9,10,10-tetrakk(4-hydroxyphenyl)anthracene (TGETA) in order to study structure-thermal stability-flame r e s i s p c e property relationships. In this study, trimethoxyboroxine (TMB) and diaminodiphenylsulfone (DDS) are employed as the curing agents. The char yield at 7 0 0 O C under a nitrogen atmosphere and the glass transition temperature (Tg) for the uncured resins decrease according to the sequence TCETA > DGEFX > DGEA > DGEBF > DGEBA. The Tg values for these cured epoxy resins are OCEBA < DGEBF < DGEFX < DGEA. A T, for the TGETA is not obtainable but would be expected to be the highest. The char yields a t 700°C of these cured epoxy resins have the same trend as the uncured resins. DGEBF, DGEFX, DGEA. and TGETA added to the DGEBA system show increases in the char yield, T,, and oxygen index with increasing concentration of these novel epoxy resins.

Thermal decomposition, combustion and flame‐retardancy of epoxy resins—a review of the recent literature

“…Lin and Pearce47 and Chen et al 48 showed that the OI of epoxy resins correlates with the charring performance. Le Bras et al 35 found correlations between OI and peak of heat release rate and ignition times measured in cone calorimetry.…”

“…Epoxy resins cured by phenol formaldehyde resin are to some degree inherently flame‐retardant because of the significant charring tendency of the phenolic component. The char yield can be increased by using special epoxy monomers containing highly aromatic bisphenols (eg phenolphthalein, bisphenol‐fluorenone,41, 47, 50 bisphenol‐anthrone and tetraphenol‐anthracene48) or those containing double bonds able to undergo the Diels–Alder reaction (eg mono‐, di‐ or trihydroxystyrylpyridine) 42. These monomers were cured either alone or in combination with regular grade epoxy monomers (eg the commercial diglycidyl ether of bisphenol A (DGEBA)), resulting in a higher crosslink density and showing an increase of OI from 20 for DGEBA to almost 40 for highly aromatic monomers.…”

Crystal structure, curing kinetics, and thermal properties of bisphenol fluorene epoxy resin

“…Synthesis of DGEBF had been reported previously,13–15 we improved the method and got DGEBF monomer with high epoxy value.…”

“…Therefore, with the addition of fluorene group to the backbone of polymers, the improved polymers are considered worthy of further study in terms of their properties 9–12. The introduction of fluorene group into epoxy resins has been reported and studied during past few years 13–17. Korshak et al and Chen et al synthesized diglycidyl ether of 9,9‐bis(4‐hydroxyphenyl) fluorene (DGEBF) and studied the effect of chemical structure on the curing and thermal properties of the cured resins 13, 14.…”

“…The introduction of fluorene group into epoxy resins has been reported and studied during past few years 13–17. Korshak et al and Chen et al synthesized diglycidyl ether of 9,9‐bis(4‐hydroxyphenyl) fluorene (DGEBF) and studied the effect of chemical structure on the curing and thermal properties of the cured resins 13, 14. They found that polymers with a fluorene between the two phenyl groups show a better thermal property.…”