Abstract: In air atmosphere, the mass loss of ABS resin at four different heating rates was investigated using TGA. The kinetics of thermal degradation was described using Flynn-Wall-Ozawa and Kissinger methods. It showed that there were two degradation stages; the first stage between 350 and 450 ℃ was the rapid degradation with activation energy (Ea) about 200 kJ/mol; the cross-linking reaction coupled with the degradation. When the mass loss in the range of 80 %~90 %, char formation was observed with Ea increasing to 262.81 kJ/mol. The second stage was the oxidation of carbon with Ea decreasing to 130 kJ/mol, so the carbon had a poor thermal stability. The reaction order of ABS thermal degradation was found to be 0.946, so the mechanism of ABS thermal degradation was controlled by the processes of random nuclear formation and growth. The thermal degradation occurred in the bulk rather than surface of ABS, so the gas of thermal degradation could not be burnt completely and lead to black smoke and dripping.

Key words: acrylonitrile-butadiene-styrene copolymer, cross-linking, charring, thermal degradation kinetics, degradation mechanism, activation energy