Reversible crosslinking in epoxy resins. II. New approaches

Epoxy resins of varying epoxy equivalent weight were crosslinked with 4,4*‐dithiodianiline (DTDA) at a 2/1 mole ratio. Resin of equivalent weight 190 (Epon 828) was cured with DTDA at mole ratios varying from 2/1 to 1.25/1. Properties of cured resins were evaluated and their reduction was investigated. Under the conditions used, reduction to the point of complete solubilization was possible providing crosslink density did not exceed a threshold value tentatively established as M c = 400 −; 500. Recurring of reduced resins was accomplished by oxidation and by reaction of thiol groups with polyfunctional reagents, including bismaleimides and polyepoxides.