PYROLYSIS-THERMOGRAVIMETRIC ANALYSIS OF TIRES AND TYRE COMPONENTS

Three samples of tyre of known rubber composition were pyrolysed in a thermogravimetric analyser under nitrogen at heating rates from 5 to 80 K min(-1). In addition, the major rubber components of the tyres-styrene-butadiene rubber (SBR), natural rubber (NR) and polybutadiene rubber (BR)-were pyrolysed separately under the same conditions. The kinetic parameters were calculated. An increase in heating rate shifted thermal degradation to higher temperatures. The tyre samples showed two distinct areas of weight loss, representing a lower and a higher temperature of decomposition. The char yield from the tyres, 32-42 wt%, depended on tyre composition. The char yields from the pure rubber components were all <4 wt%, suggesting that the carbon black component of the tyre is the main source of char. SBR decomposed mainly at higher temperatures of pyrolysis, NR at lower temperatures, and BR at both higher and lower temperatures. The thermal decomposition of the tyres could be related to their composition. The mechanism of the thermal degradation of tyres and tyre rubber components is reviewed.