Influence of curing mode on formation of epoxy composite structure in the presence of carbon nanotubes

The influence of curing modes on thermomechanical characteristics of epoxy nanocomposite ED-20/4-4 diaminodiphenylsulfone/carboxylated carbon nanotubes (CNTs) is studied. It is shown that the conditions of insufficiently high temperatures of curing in the epoxy compositions modified by functionalized CNTs (FCNTs) lead to greater degree of conversion and higher glass transition point. With the rise of curing temperature or application of a two-step mode of curing, the glass transition point in the compositions modified by FCNTs becomes lower than in the initial samples. The probable cause of the observed effect can be retardation of epoxy oligomer branching in the near-surface layer of FCNTs and, as a result, formation of more regular networks of cross-linked chemical bonds in the presence of FCNTs.