Enhanced microwave processing of epoxy nanocomposites using carbon black powders

The conversion of electromagnetic energy into heat depends largely on the dielectric properties of the material being treated. Therefore, the knowledge of dielectric properties of the test specimen is required in order to understand the extent of curing using microwaves. In this study, a detailed investigation is carried out by considering a number of carbon black (CB) samples having particulate sizes in the range of 15–65 nm. The dielectric properties of the synthesized CB/epoxy nanocomposites, before and after microwave curing, are measured using the advanced cavity perturbation method (CPM). It is observed that the CB/epoxy nanocomposite having smallest particulate size i.e., 15 nm attains the maximum value of dielectric constant (ε_r′) and loss tangent (tan δ) of 10.79 and 0.05, respectively. These results indicate that the epoxy reinforced with the CB having least particulate size would interact more effectively with microwaves, which are confirmed by the experimental data showing that the nanocomposite with smallest CB particle size of 15 nm requires the minimum curing time. The dielectric properties especially the loss factors of fully cured samples are found to decrease after curing indicating that the dielectric properties of post cured samples can provide an idea about the extent of curing. At last, thermal, mechanical and morphological analyses are also performed on all the microwave cured epoxy samples.