Study On Paint Remover Of Enameled Wire And Its Microscopic Mass Transfer In Polyester

To relieve the contradiction of the rapidly increasing demand and seriously shortage of copper, it is of great practical significance to finish the research and development of a paint remover, which is high efficiency and low toxicity, applicable to a wide range of enameled wire and at the same time suitable for modern automated production. According to dissolution characteristics of polymer and the selection principles of the solvent, also taking the insulating paint materials of the enameled wire into account, an appropriate paint remover was explored. It can be found from the experiment that the mixture of dichloromethane and activator is an ideal paint remover, since it can remove all kinds of enameled wire paint in 30 minutes. At the same time, the optimum using conditions of the paint remover were figured out through a series of single factor experiments, and they are as follows:The volume ratio of dichloromethane and activator is 5:1, the temperature is 313.15 K and the enameled wire length is 2-3 cm. The copper got from the enameled wire is of high quality with a bright color. The copper was detected by the X-ray photoelectron spectroscopy and it can be found that there was a very little chlorine element on it, which can be ignored. From this test it can also be found that the copper can be easily cleaned just with pure water. The copper ion content in the used paint remover was measured by atomic absorption spectrometry, and the results showed that the copper was hardly to be corroded by the paint remover during the paint removing process. The recycling performance of the paint remover was proved to be very good after recycled several times.Actually, to remove the paint on the enameled wire, the solvent must wet the paint surface and penetrate by diffusion, swell the film, lift off the paint by breakage of the adhesive bonds between the film and the substrate. Hence the diffusion data of a solvent is an important symbol to evaluate its paint remove ability. Based on the Van Deemter model of chromatographic process, the infinite dilution diffusion coefficients of dichloromethane, chloroform, and carbon tetrachloride in polyethylene terephthalate (PET) have been measured over a wide range of temperatures from 373.15 K to 413.15 K by inverse gas chromatography (IGC). The relationships between the infinite dilution diffusion coefficients and molecular size of solvent, as well as temperature were investigated. The results were as follows. Firstly, at a certain temperature, the infinite dilution diffusion coefficient increase with the decreasing of chlorine atoms number in the chlorinated methane, which means the increasing molecular size of solvent is a disadvantage for the diffusion process of solvent molecule in PET. Secondly, the increasing of temperature can accelerate the diffusion of solvent in PET, which follows Arrhenius relationship.Meanwhile, the infinite dilution diffusion coefficients of chlorinated methane in PET were compared with the theoretical predictions by Vrentas-Duda free volume theory. The results indicated that, due to the strong molecular interactions in the PET-chlorinated methane systems, it is unacceptable to neglect the diffusivity energy term, which can be got using the solubility parameters of polymer and the solvents, in the Vrentas-Duda predictive equation as usually did. The empirical method used to estimate the jumping unit volume of polymer in the traditional predictive method is not applicable to PET. These process methods will result in poor predictions for PET/chlorinated methane systems. The good agreement between the experimental data and the predictions results considering the energy term indicates that it is reasonable to take it into account for PET/chlorinated methane systems and use the semi-predictive method to determine the parameter (?). In addition, once the diffusivity activation energy and the parameter (?) were obtained from part of the determined diffusion coefficient, the free volume theory can be used to predict the infinite dilution diffusion parameters at different temperatures well for those systems with strong molecular interactions. Besides, it should be noted that the diffusivity activation energy item plays an important role in the prediction of the diffusion data for those systems with a strong molecular interaction, and more attention needs to be paid to the contribution of the diffusivity energy to the mass transfer process.