Rheology and kinetics are a pair of indispensable attributes in defining thermally reactive polymer coatings or paints. In this work, volatile organic compounds-free epoxy coating cure paths under heat were characterized via viscoelastic and kinetic behaviors with functional powder coating formulations as examples. As a result, when it comes to an application-oriented formulation, the essential meanings of the gel point, the minimal complex viscosity and the shear moduli from dynamic rheologicai curves, as well as the maximum cure reaction rate, and the peak temperature from differential scanning calorimetry (DSC) exothermic profiles were quantitatively interpreted with respect to dynamic viscosity, modulus, and the instant extent of cure. Events of vitrification and de-vitrification in a cure process are pertinently observable for high glass transition temperature epoxy formulations, unless a fast rate of heating is employed to a high enough temperature. Complete cure description provides strong insights into product development, allowing flow and cure properties to be balanced for maximum line performance, and is applicable to nearly all B-staged thermosetting systems of 100% solids such as conditioned prepregs, adhesives, and underfills besides epoxy-based liquid, e-coat, and powder primers or overcoats.
展开▼
