Co-pyrolysis characteristics and flammability of polylactic acid and acrylonitrile-butadiene-styrene plastic blend using TG, temperature-dependent FTIR, Py-GC/MS and cone calorimeter analyses

The plastic blend (PLA-ABS) of polylactic acid (PLA) and acrylonitrile-butadiene-styrene (ABS) is a promising material with great toughness and environmental-friendly potentials. Nevertheless, little research has focused on PLA-ABS co-pyrolysis and combustion. This work explores the pyrolysis characteristics and flammability of PLA-ABS blend with a mass ratio of 1:1. The thermogravimetric analysis shows that during the co-pyrolysis of PLA-ABS the individual pyrolysis of PLA and ABS is much faster than the corresponding pyrolysis rate of PLA and ABS alone. The FTIR analyses of solid residues indicate that PLA and ABS do not react chemically in the solid phase, hence the volatile products of co-pyrolysis are similar to those of pure materials. Through Py-GC/MS experiments, characteristic products of ABS induced by PLA-ABS co-pyrolysis at 330 °C were identified where the original ABS has not started to pyrolyze. This finding concludes that the co-pyrolysis enhances the depolymerization of components, leading to the characteristic products appearing at a lower temperature. Finally, the cone calorimeter experiments show that the PLA-ABS blend produces the highest peak heat release rate during combustion which is 93%–182% and 5%–15% higher than that of PLA and ABS, respectively. The cone calorimeter results further confirm the enhanced depolymerizations induced by co-pyrolysis.