Rationally designed lentinan outer layer to improve the comprehensive performance of flame-retardant cotton fabrics

As the most widely used natural fabric, cotton fabric is highly flammable with serious fire hazard concerns. The use of biomass materials to impart flame resistance to fabrics is always a hot topic of interest. In this work, a novel durable flame retardant cotton fabric (Cotton-APA/LNT) was fabricated by successively covalent bonding ammonium phytate (APA) and lentinan (LNT). The Cotton-APA/LNT fabric sample had a highly limiting oxygen index (LOI) value of 51.5 % and was self-extinguished in the vertical burning test (VBT) at 18.0 % weight gain. The peak heat release rate and total heat release values were decreased by 91.5 % and 46.0 %, respectively compared with those of the control cotton. Besides, after 50 laundering cycles (LCs), the fabric was still self-extinguished in the VBT with an LOI value of 34.2 %. APA fully strengthened the role of acid source by the presence of LNT. The constructed LNT outer layer showed comprehensive improvements in thermostability, flame retardancy, smoke suppression, durability, and breaking force. Specifically, the Cotton-APA/LNT sample had a higher LOI value (↑4.3 %), lower total heat release (↓23.8 %), lower total smoke production (↓29.1 %), higher thermostability (↑27 °C under air), better char formation ability (↑2.0 % under air), higher durability (self-extinguished in the VBT after 50 LCs), and higher breaking force (↑32.5 % in the warp direction and ↑33.9 % in the weft direction) compared with those of Cotton-APA sample. This work has proposed an advanced approach for fabricating eco-friendly durable fire-safety cotton fabrics.