Cure Kinetics and Network Development of a Very High Tg Naphthalene-Based Epoxy Amine Network

A comparative study of the reaction mechanism, cure kinetics, and network development of two tetrafunctional epoxy resins cured with diamino diphenyl sulphone is presented here. Bis(2,7 diglycidylether naphthalenediol) methane (NNE), a highly aromatic and rigid epoxy resin consisting of glycidyl ether epoxide groups, is compared against tetraglycidyl diaminodiphenyl methane (TGDDM), a more flexible glycidyl amine based epoxy resin. A TGDDM/NNE blend is further prepared to explore the differences between glycidyl ether and glycidyl amine in high glass transition temperature networks. Near-infrared spectroscopy, differential scanning calorimetry, and dynamic mechanical thermal analysis are all used to understand the importance of the rigid bisnaphthalenediol motif and glycidyl ether functional groups with respect to the cure reaction and network transformations. The NNE cures more rapidly during the chemically controlled region, although vitrification and the onset of diffusion-controlled reactions begin earlier, ultimately resulting in lower epoxide conversions. Finally, time–temperature transformation diagrams are constructed to understand the relationship between gelation, vitrification, full cure, and degradation.