Ni–Ca/D152, D152 had more extensive temperature range of water elimination from 100 C to 500 C when carbon- ized. The decarboxylation of D152 occurred primarily in the range of 335–500 C. The peaks of CO2 and CO were at 440 C and 470 C respectively. By comparing the curves of thermogravimetric analysis (Fig. 2) and differential ther- mal analysis (Fig. 3) of preoxygenated Ni–Ca/D152 and D152, it can be concluded that the pyrolysis of D152 was significantly accelerated by the catalysis of nickel and calcium.
Based on the above analyses, three stages of the thermal decomposition of Ni–Ca/D152 are determined: (1) around
15% of weight lost from 30 C to 380 C. This weight loss was basically resulted from de-water and decarboxylation; (2) a sharp weight loss took place from 380 C to 520 C due to the formation of a great amount of tar which con- densed and flowed out from the pyrolysis tube. These decomposition reactions were companied by a huge exo- thermal change in the same temperature range (Fig. 3); (3) a weight loss slightly proceeded in the heating from
520 C to 800 C. Elemental analysis showed that C/H
atomic ratios of the resin carbonized at 400 C was
1:1.04, carbonized at 500 C was 1:0.37 and carbonized at
600 C was 1:0.1, which strongly supported the conclusion
that the major decomposition and structure rearrangement
occurred in the stage (2).