Using the Friedman method to study the thermal degradation kinetics of photonically cured electrically conductive adhesives

Abstract

In this study, the electrically conductive adhesives were fabricated using vinyl ester resin and micro silver flakes, and then a high-intensity pulsed light was introduced to cure the adhesives under an ambient atmosphere at room temperature. The thermal degradation kinetics of photonically cured products was studied using the Friedman method and deduced by assuming a variable activation energy (E). The value of E spanned from 110 to 233 kJ mol−1, which first increased, then decreased, and finally increased again as the thermal degradation proceeded. The kinetic equation of thermal degradation was obtained as dα/dt = e26.62(1 − α)2.22 α 1.85e(−E(α)/RT) with E(α) = 961.73α 3 − 1453.9α 2 + 669.79α + 79.859, α ∈ (0, 1), where α was the fractional extent conversion at a given time (or given temperature). The overall order of reaction was 4.07 and >1, demonstrating that the thermal degradation was complex. With the Friedman method, a comprehensive and in-depth understanding of the thermal degradation kinetics of photonically cured electrically conductive adhesives has been achieved.