Thermal degradation and oxidation of polystyrene studied by factor-jump thermogravimetry |
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Authors: | Brian Dickens |
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Institution: | Center for Materials Science, National Bureau of Standards, Washington, DC 20234, USA |
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Abstract: | Factor-jump thermogravimetry has been used to study the activation energy of polystyrene degrading in a vacuum, in N2 flowing at 4 mm/s and in mixtures. The results show the activation energy to be 44·9 ± 0·2 kcal/mole (188 ± 0·8 kJ/mole) for degradation above 350°C in vacuum or in flowing N2. This agrees well with work reported in 1949 by Jellinek7 but with few results reported subsequently.The apparent activation energy for polystyrene losing weight above 280°C in an atmosphere of abundant O2 is 21·5 ± 0·2 kcal/mole (90·2 ± 0·8 kJ/mole). In all cases where O2 was deliberately introduced (partial pressures >4 mm Hg), the sample degraded to a black tar and the activation energy was ≤30 kcal/mole, depending on the amount of oxygen present and on the thermal history of the sample. |
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