Curing behaviors' characterization of strong and weak crosslinking systems by thermal and dynamic mechanical methods

Abstract

Curing processes of weak- and strong-crosslinking curing systems, e.g., epoxy asphalt and dicyandiamide cured epoxy resin systems, were studied by mechanical method of dynamic shear rheometer (DSR) and thermal method of differential scanning calorimetry (DSC), respectively. Results indicate that the two approaches are both sensitive to the whole curing process for strong-crosslinking system, whose curing exothermic process matches its mechanical properties' development. But for weak-crosslinking system, i.e., incompletely cured rubber-like one, whose mechanical properties' improvement lags behind its curing exothermic process, DSC is sensitive in initial stage of curing reaction, and DSR is sensitive after gel point. Furthermore, with Avrami equation, it is possible to control the curing processes for preparing products with needed mechanical properties by DSR. Therefore, although DSC method is classical, DSR and alike mechanical methods should be comprehensively evaluated in terms of involved curing systems at different curing stages as well as researchers' study purposes.