Thermal degradation and flame retardancy properties of ABS/lignin: Effects of lignin content and reactive compatibilization

Effects of alkali lignin incorporation and in situ reactive compatibilization on the thermal stability and flame retardancy of ABS were investigated. Morphology observations show that lignin can form submicron dispersed phases in ABS matrix regardless of compatibilization. Thermal analyses show that lignin will cause a slight thermal instability of ABS due to its relatively lower thermal stability, and compatibilization reaction has little effluence on that. However, lignin can slow the degradation process and increase the char residue of ABS with increasing lignin loading, and the compatibilization does not markedly affect them. Cone calorimeter tests demonstrate that lignin can significantly reduce the heat release rate, and slow the combustion process of ABS, e.g., 20 wt% lignin causing a 32% reduction in peak heat release rate (PHRR). The compatibilization can further reduce the flammability of ABS due to the improved char layer. The char residue analyses indicate that the formation of protective char layer of lignin is primarily responsible for the enhanced flame retardancy.