Development of Properties During Cure of Epoxy and Acrylate Coating Materials

Abstract

The development of time-dependent properties with conversion during cure of step-wise reacting epoxy and chain-wise reacting acrylate coatings has been investigated. Using a torsional dynamic mechanical analyser, dynamic shear modulus and change in sample thickness was monitored simultaneously, thus giving information on both the physical properties and the progress of the reaction in one experiment. Isothermal cure below and above the ultimate glass transition temperature, i.e. with and without vitrification at the cure temperature, was compared. The epoxy and acrylates were found to behave similarly on cure above the ultimate glass transition temperature but to exhibit differences during vitrification on cure below this temperature. From the shrinkage and storage moduli, approximate values of the relaxation time and relaxation modulus as a function chemical conversion were calculated.