Preparation of phytic acid‐based green intumescent flame retardant and its application in PLA nonwovens

Abstract As a bio‐based and biodegradable textile, poly (lactic acid) (PLA) nonwovens are an important supplement for nature cotton, flax, and silk. This work concentrated on improving the flame retardancy of PLA nonwovens by introducing a novel eco‐friendly flame retardant (TPA), which was synthesized from phytic acid and tris(hydroxymethyl)methyl aminomethane. The structure, composition, and properties of TPA were fully characterized, and the results showed that TPA owned excellent thermal expansion performance. The flame retardancy of PLA nonwovens was efficiently improved by the presence of TPA. For PLA/23%TPA sample, the molten droplet was inhibited and the damaged area was decreased by 71.8%. The LOI value was increased from 18.0% of control PLA to 26.5%, and the peak heat release rate (pHRR) and total heat release rate (THR) were decreased by 30.2% and 29.0%, respectively. Besides, TG analysis confirmed a great char‐forming capability of the treated fabrics with the residue amount increasing from 1.8 to 11.6 wt% at 800°C. TPA released vapor, phosphorus radicals into the gas phase, and also promoted to form a compact char barrier in the condensed phase, which enhanced the carbonization and flame retardancy of PLA nonwovens. To our best knowledge, our work is one of the few studies focused on the flame retardancy of bio‐based PLA nonwovens.