Cure of epoxy resins with cyanoacetamides

Abstract

Cyanoacetamides are a novel class of curing agents for epoxy resins. Since reaction products of epoxy compounds with cyanoacetamides have not yet been described, we investigated the reaction of phenyl‐glycidylether (PGE) and N‐isobutylcyanoacetamide (NICA) under the conditions of the epoxy cure (120–150°C). Twenty‐two fractions of the reaction product have been separated by preparative TLC and characterized by FD and MS mass spectroscopy. The structures of 10 reaction product have been elucidated by MS, NMR, and IR techniques. They belong to the classes of cyclic urethanes, spiro‐dilactones, cyclo‐oxa‐1‐hepten‐4‐one‐2, pyrimidones, aminocrotononitrile, and tertiary amine. This complex model reaction mixture does not enable us to propose a curing mechanism. However practical cure of Bisphenol A diglycidylether (BADGE) yields clear and tough solids with a glass transition temperature up to 200°C, good mechanical strength, and high adhesion to metal surface. Cyanoacetamides are latent hardeners requiring a curing initiator. Since N‐4‐chlorophenyl‐N′‐dimethylurea is a latent initiator, liquid, homogeneous, storage stable “one shot” systems can be formulated which harden quickly above 120°C. Heat aging properties of cured specimens are reported. A series of novel liquid, resinous, and crystalline cyanoacetamides and their potential as curing agent are described.

Adhesives Based on Poly(glycidyl methacrylate‐co‐butyl acrylate) with Controlled Structure: Curing Behavior and Adhesion Properties on Metal Substrates

“…On the contrary, it is soluble in liquid epoxy resins and in a wider range of solvents than DICY, which represents a great advantage, being able to be used in adhesives, powder coatings, and laminates. Regarding the curing of epoxy resins using cyanoacetamides, Renner et al [ 41 ] have investigated the products resulting from this reaction, determining cyclic urethanes, spirodilactones, cyclo‐oxa‐1‐hepten‐4‐one, pyrimidones, aminocrotonitrile, and tertiary amine. Far from presenting a mechanism capable of explaining the formation of this catalog of products, these authors point to the presence of a T g during the curing of a DGEBA at approximately 200 °C, in addition to a high adhesion to metal surfaces.…”

“…Far from presenting a mechanism capable of explaining the formation of this catalog of products, these authors point to the presence of a T g during the curing of a DGEBA at approximately 200 °C, in addition to a high adhesion to metal surfaces. [ 41 ]…”

“…Far from presenting a mechanism capable of explaining the formation of this catalog of products, these authors point to the presence of a T g during the curing of a DGEBA at approximately 200 °C, in addition to a high adhesion to metal surfaces. [41] With this background, the curing dynamic study of the GMA-BA copolymer and 2-CA by DSC is displayed in Figure 3a. This DSC-gram shows a T g0 of our system at 45 °C, and then two endothermic peaks, the first one with low intensity at 86 °C, and the second one at a higher temperature close to 109 °C.…”