Lignin a sustainable and renewable flame retardant for abs

Lignin is an abundant polyphenol biopolymeric material. Due to its aromatic structure, it develops a char upon fire and it is then a potential candidate to become an efficient flame retardant (FR) in polymeric materials. In this work, lignin was used as flame retardant in acrylonitrile-butadiene-styrene (ABS). Phosphorus is one of the basic constituent of flame retardant and phosphorylation of lignin was carried out to improve its fire-retardant efficiency. The functionalization of kraft lignin (LIG) were done using phosphorus oxide by a simple and industrially feasible process to yield phosphorylated lignin (P-LIG). When incorporated at 30 wt.% in ABS, ABS/LIG and ABS/P-LIG exhibit a significant reduction of the peak of Heat Release Rate (pHRR) measured by cone calorimetry compared to neat ABS. It is shown that P-LIG promotes char formation. The char is cohesive and acts as a protective layer.