Effect of Microwave on Diffusion Behavior of Dye Molecules

For the purpose of applying microwave dielectric heating technique to textile processing, the effect of microwave irradiation on the diffusion behavior of the dye molecules was studied. The diffusion coefficient D of the acid dye (Orange II) in the nylon 6 film was measured under the constant temperature (80°C) by microwave dielectric heating. The diffusion distance of the dye in the films by the microwave heating became larger than the conductive heating. The diffusion coefficients by the microwave method (Dm) and conductive method (Dc), calculated from the Fichian diffusion profiles, were Dm = 2.3×10-9cm2/sec , Dc = 1.7×10-9cm2/sec, respectively. This means that the microwave irradiation gives the effect to increase the diffusion coefficient on the dyeing process. This effect by the microwave heating increased at high temperature which had a high microwave irradiation. It is presumed that the increase of the diffusion coefficient arise from the temperature change in the minute scales of the dye solution by the microwave heating, that is, the local heat generation would occur in the vicinity of the dye molecules which have absorbed the microwave energy.