An investigation into welding of engineering thermoplastics using focused microwave energy

Microwaves have been used for many years in industrial heating applications because of their ability to heat materials volumetrically. The dielectric properties of a material determine its ability to absorb microwave radiation. In this paper, the dielectric properties of engineering thermoplastic materials, which include ultra high molecular weight polyethylene (UHMW PE), polycarbonate (PC) and acrylonitrile-butadiene-styrene (ABS) polymers under room temperature conditions have been explored. In addition to this, a new novel process for joining such polymers using microwave energy is presented. Basically, the thermoplastics joining process is carried out in two separate stages, the first stage consisting of directly inducing microwave energy to the specimen joint interface, whilst the second state comprise of applying primers in the form of epoxy-based resin to promote the joining of the materials by means of microwave energy. Tensile tests were conducted to determine the bond strength achieved at the specimen joint interface. In addition, microscopic examinations of the fractured joints were performed in order to analyze the overall bond quality. Finally, a comparison was drawn between the heating time required, the bond strength and quality of joint achieved at the interface. Concluding remarks underline the potential capability in terms of speed, joint strength and versatility for this high-energy-rate process.