부산대학교 도서관

Recently, evolved gas analysis-mass spectrometry (EGA-MS) usable in air atmosphere was developed by adding a gas inlet to supply helium gas flow to dilute the air flow through the pyrolyzer. When using a quadrupole mass detector for the EGA-MS system, however, it is sometimes difficult to differentiate the thermooxidative products from thermolysis ones because they often provide the fragment ions with the same nominal m/z value. In this work, the EGA-MS system was modified with the use of a high-resolution time-of-flight mass spectrometer. By using the modified system, polypropylene (PP) was subjected to high-resolution EGA-MS in air atmosphere. In the high-resolution mass spectrum of the evolved gas of PP, the most intense fragment ion of the thermooxidative product, CH3CO+ at m/z 43.018 was clearly separated from that of the thermolysis product, CH3CH2CH2+ at m/z 43.054. The extracted ion current EGA profiles of each fragment ion demonstrated that the thermooxidative reactions of PP prevailed over the thermolysis ones under the EGA conditions in air atmosphere. Furthermore, it was suggested that the contribution of the thermooxidative reactions increased with an increase in the air flow rate during EGA.