Microwave Joining of Polymers

Some products have a very complex structure to be molded as a single piece; this creates a hindrance for the manufacturers to let them mold single component products using polymers. Thus, in manufacturing of many plastic-based products into final products, assembly of subcomponents plays an important role. Presently, the most efficient joining method for plastics is welding. Compared to conventional heating techniques, microwave heating has many advantages due to the ability to heat the material directly through interaction of electromagnetic radiation. Therefore, microwaves can be seen as a direct means of forming and welding since it can rapidly melt thermoplastics in a highly localised way. In this study, considering multiwalled carbon nanotubes (MWCNTs) as a good microwave absorber, it is used as a susceptor for the microwave welding of high-density polyethylene (HDPE) and further results are analysed to carry out in-depth study of microwave welding. The dispersion created by ethanol and multiwalled carbon nanotubes in an ultrasonic bath, is dropped on a targeted area on the dumbbell-shaped sample and then dried in an oven for 30 min at 45?C for further microwave irradiation of 800W in a domestic microwave oven. Then with the help of tensile testing, the strength of the weld is tested and scanning electron microscopy (SEM) is used to analyse the cross section of the welded joint. In the study of the effect of MWCNT concentration and microwave heating duration, it is found that as the heating duration increases from 2 s to 8 s, the joint strength increases but decreased when the duration is further increased to 10 s. When duration of 10 s is used, the SEM images captured void formation at the joint interface which resulted in lowering of joint strength. The effect of the MWCNT concentration in the dispersion shows increased joint strength when the concentration is increased from 0.25 wt% to 0.75 wt% but decreased in the presence of 1.00 wt% concentration.