INVESTIGATION OF NON-THERMAL EFFECTS PRODUCED BY ULTRASONIC HEATING ON CURING OF TWO-PART EPOXY ADHESIVE

摘要

Rapid curing of structural adhesives by ultrasonic heating has been demonstrated successfully in recent work. Therefore, it is important to examine whether ultrasound would induce non-thermal effects that accelerate the reaction rate of the adhesive. In this paper, Differential Scanning Calorimeter was used to carry out thermal analysis of the reaction kinetics of a two-part structural epoxy adhesive. A chemical model based on a four-parametric semi-empirical equation was developed to distinguish the non-thermal effects from ultrasonic vibration from the thermal effects resulting from ultrasonic heating. It was found that the non-thermal effects was more significant at the beginning of the curing process but it gradually diminished as the heating time was increased. The conversion of the epoxy adhesive produced by ultrasonic curing at 50 seconds was almost three times higher than that obtained by thermal heating.