Anhydride curing of epoxy resins via chain reaction

In contrast to common curing reactions, the anhydride curing of epoxies follows a living anionic chain growth. The resulting consequences of this mechanism, i.e. (1) DP n = a[M o ]/[I o ], (2) first‐order kinetics and (3) Poisson chain‐length distribution were tested with the phenyl glycidyl ether/phthalic acid anhydride system, using l‐methyl imidazole. Overall agreement was found and the observed deviations could be explained with a modified Poisson process. Conformational properties of the resins were measured by static and dynamic light scattering and by viscometry. These were compared with the quantities of a corresponding branched system prepared with a mixture of phenyl glycidyl ether and bisphenol‐A diglycidyl ether. Typical deviations to smaller dimensions were observed at high molar masses as a result of increasing branching.