Kinetic response of thermosetting adhesive systems to heat: physio-chemical versus mechanical responses

The kinetic response of four thermosetting adhesive systems (UF and UF-m, each with two molar ratios) to heat has ben explored. In preliminary studies, gelation time and Differential Scanning Calorimetry (DSC) measurements were made and activation energy values derived for the latter using Kissinger's method. The results are compared with isothermal bond strength development data collected using the ABES (Automated Bonding Evaluation System) approach. In this, miniature bonds are formed under highly controlled conditions at a variety of preselected isothermal temperatures and pressing times and immediately thereafter destructively tested in shear mode. Reactivity indices have been determined by analyzing regressed isothermal bond strength development rates from the ABES tests and these values are compared with gelation and DSC values. In addition, the ABES technique has been modified to enable the adhesion kinetics of miniature resinated fiber discs to be explored in shear mode, and preliminary results are presented.