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 Ϫ40°C, respectively. The high temperature cured purified lacquer film showed a secondary relaxation at around Ϫ50°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 ⌬⑀.

Curing behaviors of Korean Dendropanax lacquer determined by chemical and physical measures

“…In recent years, natural lacquers such as a cashew nut shell liquid (CNSL) lacquer and oriental ( Rhus vernicifera ) lacquer have attracted considerable interest because of the excellent protective and decorative properties. These have been used as surface coatings for wood, porcelain, metalware, and so forth 2–13. Over the past 45 years, synthetic lacquers have competed with natural lacquers.…”

“…Oriental lacquer is made from the sap of lacquer trees, Rhus vernicifera , primarily in Korea, Japan, and China. A number of studies have been made on the chemistry, curing behavior, film properties, and viscoelastic and surface morphological properties 7–13. More recently, many patents or studies related to the applications of CNSL and oriental lacquers have been published 2–13…”