Mesoscopic Heterogeneity in Curing Process of An Epoxy Reaction System

To confer desirable mechanical properties onto an epoxy resin, it is necessary to understand and control a spatial heterogeneity induced in it upon the curing process. In this study, the spatial heterogeneity in a mixture of hydrogenated bisphenol-A diglycidyl ether and 1,4-cyclohexanebis(methylamine) with a molar ratio of 2:1 was examined at a given temperature as a function of time by a particle tracking technique, in which local physical properties can be examined on the basis of the thermal motion of a probe particle. Polystyrene particles with diameters of 200, 120 and 50 nm were used as a probe, leading to observations with different length scales. We could successfully track the time evolution of spatial heterogeneity in the system during the curing reaction and combine the bulk mechanical properties of the resultant resin.