Fast polymerization at low temperature of an infrared radiation cured epoxy-amine adhesive

TL;DR

This study demonstrates that infrared radiation can rapidly cure epoxy-amine adhesives at low temperatures within minutes, potentially enabling a cold, on-demand curing process without catalysts or accelerators.

Contribution

It reveals the role of non-thermal effects in infrared curing, showing how infrared radiation accelerates polymerization by reducing energy barriers in epoxy-amine reactions.

Findings

Infrared curing achieves rapid polymerization in minutes at low temperature.

Non-thermal effects contribute to accelerated curing via infrared radiation absorption.

Curing process does not require initiators, catalysts, or accelerators.

Abstract

In the industry, the cure time of two-component adhesives is very important for a cost-effective manufacturing. Too fast, it does not favor the application of the product and the control of bonded joints. Too slow, it leads to long process times and too high process costs. The best compromises are two-component adhesives that cure slowly at room temperature and can reach full polymerization in minutes, on demand. In this paper, the curing behavior of a model poly-epoxide adhesive (a stoichiometric mixture of a pure epoxy and amine) polymerized with infrared radiation will be studied. The kinetic follow-up of this polymerization will be carried out by thermal analysis (determination of the residual heat peak by Differential Scanning Calorimetry-DSC). This study paves the way to a cold and universal cure-on-demand process, which means achieved in few minutes at low temperature without any initiators, catalysts or accelerators. Basically, infrared curing can be possible thanks to an increase in temperature (called thermal effect). But it has been shown that a "non-thermal effect" could also be involved in accelerating kinetics with infrared. This increase due to a non-thermal effect, suggested as a function of the infrared radiative flux, has been shown to be possible thanks to the absorption of infrared radiation, leading to a reduction in the energy barrier of the primary epoxy/amine reaction.