Epoxy oligomer

TetrabromobisphenolA. TBBPA is the largest volume reactive flame retardant. Its primary use is in epoxy resins (see Epoxyresins) where it is reacted with the bis-glycidyl ether of bisphenol A to produce an epoxy resin having 20—25% bromine. This brominated resin is typically sold as a 80% solution in a solvent. TBBPA is also used in the production of epoxy oligomers which are used as additive flame retardants. 

Brominated Phenols. Tribromophenol [75-80-9] and dibromophenol [615-58-7] are both prepared through bromination of phenol. These are not actually used as reactive flame retardants, but rather as starting materials for other flame retardants such as BTBPE [37853-59-1] and epoxy oligomers. 

Rozengerk,v. A. Linetics, Thermodynamics and Mechanism of Reactions of Epoxy Oligomers with Amines. Vol. 75, pp. 113 — 166. 

Chain Extendable Urethane Modified Epoxy Oligomer. The chain extendable urethane modified oligomers were prepared by combining equimolar amounts of epoxy-diol adduct and half-blocked diisocyanates, and heating the resulting mixture at 80°C for 4-6 hours until the isocyanate Infrared band disappeared. 

Figures la and lb show the OH and NH infrared bands of the oligomer as a function of temperature in uncatalyzed and catalyzed formulations. The uncatalyzed urethane modified epoxy oligomer shows only small changes in the OH/NH absorbance ratio at temperatures below 165°C only about a 60% conversion of the blocked isocyanate was observed. In contrast, sample of the oligomer catalyzed with 0.5% dlbutyl tin dilaurate shows nearly complete chain extension at temperatures as low as 130°C.

Kinetics, Thermodynamics and Mechanism of Reactions of Epoxy Oligomers with Amines... 

In this review, modem interpretations of the kinetics, thermodynamics and mechanisms of curing of epoxy oligomers with primary, secondary, and tertiary amines and their mixtures, as well as the structure of the resulting polymers are discussed. The effect of the structure of the reagents on their reactivity is analyzed. Kinetic peculiarities of the deep stages of the curing process are emphasized Problems to be solved in the future are formulated. 

A great number of investigations has been devoted to the chemistry of epoxy, compounds and clarification of the mechanism of curing of epoxy oligomers with various hardeners, summarized in monographs 1,12,19-23) and reviews24-251, which have become, however, somewhat obsolete. 

In curing of epoxy oligomers with primary and secondary amines, the following main reactions take place1 ... 

The epoxy-oligomer curing with amines has an autocatalytic character due to the accumulation of hydroxyl groups during the reaction [cf. Scheme (1)]. 

So, the curing mechanism of epoxy oligomers with amines is rather complicated apd, to a first approximation, may be described by Scheme (8) taking into consideration all the donor-acceptor interactions of the starting reagents with the reaction products and with each other... 

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