Microwave Heating of Multi-Layered Composites for Bonding

A detailed theoretical analysis has been carried out to study selective heating of multilayered dielectric composite under microwave heating by solving an unsteady energy equation with an electric field and frequency dependent heat source term. The source term is computed from simplified Maxwell’s equations under plane wave assumption. Analytical solution obtained from this study is used to understand the effect of layer thickness on temperature distribution in a thin layer of poly-aniline sandwiched between two polymer (PMMA) substrates. It is found that dielectric properties, sample thickness and processing time have significant influence on the microwave heating pattern. The highly dielectric poly-aniline absorbed more microwave power than that of PMMA and attained temperature above the melting point of PMMA in less than 2 minutes. These results show that localized melting of PMMA can be achieved using household microwave. This analytical investigation on multi-layered composites will provide a significant insight to understand and overcome the challenges of selective heating and localized bonding technique.