THERMAL-DEGRADATION OF THE LACQUER FILM B Y PYROLYSIS-GAS CHROMATOGRAPHY MASS-SPECTROMETRY

Sap of the lacquer tree dries into a brilliant and tough film. It is a latex composed of urushiol, water, plant gum, water-insoluble glycopr otein, and laccase. Thermal degradation of the lacquer film was studie d by pyrolysis-gas chromatography-mass spectrometry (PY-GC-MS) using t wo- and single-stage pyrolysis techniques. Urushiol, plant gum and wat er-insoluble glycoprotein which were isolated from the lacquer sap was used to study the pyrolytic behavior of lacquer film by single-stage pyrolysis under best optimum pyrolysis condition. The characteristic p eak appearing on the pyrograms were identified using a mass spectromet er which was directly attached to the gas chromatography. On the basis of the observed pyrograms, the degradation and polymerization mechani sms of the lacquer film were discussed. Consequently, it was evidenced that the formation of lacquer film proceeds through the side chain-si de chain C-C coupling and nucleus-side chain C-O coupling besides phen ol coupling and nucleus-side chain C-C coupling.