Pyrolysis characteristics and kinetics study of four typical trolley case materials in passenger trains

Piled-up luggage is a non-negligible fire load in passenger trains. Four mainstream trolley case materials are selected in the study, and the main components are polypropylene (TC-PP), polycarbonate (TC-PC), acrylonitrile-butadiene-styrene (TC-ABS), and PC/ABS blend (TC-PC/ABS). The pyrolysis behaviors under an air atmosphere with four heating rates are tested using a thermogravimetric analyzer, and the behavior under nitrogen with a heating rate is further tested for comparison. Two model-free methods are used to obtain the activation energy (Ea), and the reaction mechanism of the target materials is characterized. Moreover, the pyrolysis products are analyzed coupled with an FTIR spectrometer. The thermogravimetric results show that the pyrolysis processes of the four materials in air and nitrogen atmospheres differed significantly. The Ea of TC-PP, TC-PC, TC-ABS, and TC-PC/ABS obtained by the KAS method are in the range of 82.1–294.4, 93.7–394.2, 156.5–419.3, and 152.1–313.6 kJ·mol−1, respectively. Meanwhile, the values obtained by the Friedman method are in the range of 80.7–722.1, 63.6–448.9, 195.3–821.2, and 131.9–371.9 kJ·mol−1, respectively. The SB model is introduced to better characterize the reaction mechanism rather than a single existing theoretical model. The FTIR results demonstrate that the main pyrolysis product of the four materials under air is CO2.