抄録
Historically, a lot of disaters by fire have destroyed lives and properties. And fire detection system especially in the early stage has been explored. Monitoring the smog concentration and the temperature in the room are the typical method for fire detection. Nowadays influence upon the environment by the thermal decomposition products of fire becomes more important because of dioxin, PCB (polychlorobiphenyl) and their toxicity. Also new chemical species have been found in the thermal decomposition products by the development of the analytical instruments, for example, gas chromatography mass spectrometry and odor sensor. Pyrolysis mechanism of cellulose and its roasted odor were studied by odor sensor, GC-MS and TG-MS. The roasted odor was generated from 170°C when cellulose was heated and pyrolized. Odor sensor made of tin oxide semiconductor thin film detected the odor products at 170°C, which was almost the same temperature that a human nose could detect. The human and the artificial nose could be understood to sense the same evolved gas among the decomposition products. We analyzed the decomposition products of cellulose and found levoglucosan as a main product around 300-400°C by GC-MS under He condition. TG-MS study was carried out under air condition and levoglucosan was detected. Levoglucosan (mp 182°C, bp 280°C) was estimated to sublimate over the temperature of 200°C. When cellulose pyrolized, the chemical weak bonding of -O- was scissored randomly. Finally this scission stopped when it created the monomer unit of cellulose, that is levoglucosan. Considering these facts we concluded the roasted odor by the decomposition of cellulose must be levoglucosan.
