SynopsisThe common assumption in the literature is that amine complexes of Lewis acids (particularly boron trifluoride) cure epoxy resins by virtue of their dissociation to liberate the Lewis acid which then functions as the "true" catalyst. Evidence is presented to indicate that this picture of aminelewis acid complex curing may be incorrect. Another mechanism is proposed which is consistent with ( a ) lack of correlation between adduct stability and reactivity, ( b ) a similarity in reactivity of BF, adducts and the corresponding fluoroborate salts, ( e ) the relationship between reactivity of BF, and PFh adducts, ( d ) a correlation between reactivity and structure of the amine in the complex, and (e) the effect of the anion on reactivity of amine salts. The relative reactivity of the catalysts has been equated with the temperature at which gelation occurs on heating at a fairly constant rate.

No abstract

No abstract

A series of linear polyesters have been made by polymerization of dibasic acids with acetyl derivatives of p,p′‐diphenolic compounds. The diphenolic compounds were of either the dihydroxydiphenyl or the methylenebisphenol type with varying degrees of alkyl substitution. The crystallinity and first‐ and second‐order transition temperatures of the polymers are considered in terms of their chemical structures. The effects of symmetry and aromaticity are discussed.

No abstract