Enabling contactless rapid on-demand debonding and rebonding using hysteresis heating of ferrimagnetic nanoparticles. (15th November 2021) - Cheng, Xinying
Graphical abstract: Highlights: Adding ferrimagnetic nanoparticles (Fe3 O4 ) to a thermoplastic adhesive, poly(ethylene-methacrylic acid) (EMAA), enables rapid self-heating without negatively affecting the lap shear strength. A fast-heating rate of 0.4 °C/s can be achieved in EMAA containing 20 wt% Fe3 O4 by a 2-kW electromagnetic field generator. The lap-shear strength of Fe3 O4 -modified adhesive increases with the weight percentage of nanoparticles up to 5 wt%, followed by a slight decrease of around 10% when the nanoparticle concentration reaches 20 wt%. Computational modelling reveals that magnetic hysteresis loss heating by ferrimagnetic nanoparticles can achieve higher temperature than resistive heating of conductive fillers of the same weight. Abstract: Rapid and contactless on-demand debonding and rebonding of high-strength joints is a promising solution for quick attachment, repairs, disassembly, and recycling of structural systems. Herein we show that rapid and contactless on-demand debonding and rebonding can be achieved by incorporating ferrimagnetic iron oxide nanoparticles (Fe3 O4 ) into poly(ethylene-methacrylic acid) (EMAA). When subjected to an external alternating magnetic field, the ferrimagnetic nanoparticles generate localized heat which melt the EMMAA, resulting in quick (<1 min) debonding and rebonding. The strength of the adhesive bond matches that achieved by conventional oven heating, exceeding the highest value reported for reversible adhesives in the literature. The results also show that, for the first time, the ferrimagnetic nanoparticles are effective in retaining 100% of the original bond strength for up to five cycles of repeated debonding and rebonding. Analytical and computational models have been developed to characterize the effects of key design parameters, such as Fe3 O4 mass loading and magnetic flux on the heating performance and bond strength. The model correlates well with experimental results and reveals that magnetic hysteresis loss is more efficient than eddy current generated by conductive fillers for heating the adhesive. The high-strength EMAA/Fe3 O4 adhesive is a very promising solution for contactless, on-demand, repeated adhesion applications to complex geometries and in hard-to-access locations.