Dielectric characterization of relaxation and curing behavior of oriental lacquer

Abstract

Dielectric analysis was used to investigate the effects of temperature and humidity on the curing behavior of oriental lacquer and to characterize the dielectric properties of the lacquer film. It was found that the oriental lacquer could not cure to its hardened state at relative humidity less than 50% in ambient temperature and that the cure time could be shortened tremendously by increasing the curing temperature. In order to study the dielectric properties of oriental lacquer film, two films were prepared at different curing temperatures. The glass transition and secondary relaxation temperatures of ordinary oriental lacquer film, room temperature cured purified lacquer, were observed at 45 and −40°C, respectively. The high temperature cured purified lacquer film showed a secondary relaxation at around −50°C. The relationship between thermodynamic properties and chemical structures was explored based on the analysis of the dielectric relaxation behavior using Cole–Cole plots and the dielectric relaxation intensity Δϵ. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1804–1810, 2000