| Popis: |
Series of infrared spectra were recorded of chars produced by heating sucrose in vacuum at successively increasing temperatures, up to 750°C. Photothermal beam deflection spectroscopy was used. Some of the aliphatic components of the sucrose melt aromatize at a temperature as low as 200°C; the structures of the sugars are lost entirely in the 300–350°C region, and a variety of carbonylic structures are formed. The chars then change continuously in composition as the pyrolysis temperature is raised. The initially aliphatic mixture is progressively converted into a predominantly aromatic material, dehydroxylation proceeds, aliphatic groups are eliminated and/or converted into aromatic material, and the carbonylic species decrease. Also, the aromatics polymerize to form larger, polyaromatic structures. These trends continue until about 600°C. Above 600°C there is an abrupt increase in the polyaromatization, and a further decrease in functional groups. All IR-active groups are removed when 750°C is reached. |
