Susceptor Assisted Microwave Processing of Polymers for Adhesive Production

Abstract

Microwave activated adhesives were manufactured, at laboratory scale, with micro-nanosized fillers embedded in traditional thermoplastic matrix. These metal-based susceptors are highly loss materials (e.g.: iron and aluminium micro/nano-powders), which rapidly heat-up by means of the microwaves/radio frequency irradiation. The heat is then transferred to the matrix through conventional heat transfer. This is a very effective technology to create reversible adhesives suitable for many applications in various industries including the automotive and the aerospace industry. Susceptor technology is a good way to replace traditional hot-melt adhesives. Hot-melt adhesives are thermoplastic bonding materials applied as melts that achieve a solid state and resultant strength on cooling. These thermoplastics of 100% solid materials melt in the temperature range from 65 °C to 180 °C. Theoretically, any thermoplastic can be a hot-melt adhesive, however, preferred materials are usually solid up to 79.4 °C or higher. Metal particles are suitable for susceptor materials that create hysteresis heating-based Curie temperature control for polymer processing. The electrical properties of the reinforcement are mainly used for matrix melting by induction heating. Induction heating has several features, including high efficiency and economic benefits and environmental benefits. In this study we investigated a formulation of MW/activated adhesives made of LDPE mixed with aluminium micro-particles. An optimization of the best materials concentration and dimensions was carried out according with the electro-magnetic performances evaluated.