Preparation and properties of sulfomethylated lignin-based highly flexible polyurethane foam

Polyurethane (PU) can be synthesized by replacing petrochemical polyols partially with lignin, thus improving the environmental benefit and the comprehensive performance of the foam. Herein, sulfomethylated Kraft lignin (SKL) is obtained by sulfonation of Kraft lignin (KL), and then it is used as filler to synthesize the sulfomethylated lignin-based flexible polyurethane foam (SLFPUF). The effects of SKL with different sulfonations on SLFPUF are explored. Thermogravimetric (TG) analysis shows that when the sulfonation is 0.286 mmol/g, the residual mass is 12.63 % that is higher (3.35 %) compared to the control group lignin-based flexible polyurethane foam (LFPUF), indicating better thermal stability. The support factor (SF) of SLFPUF-0.286 is 4.99, higher than that of LFPUF (1.89), showing good softness. The air flow of SLFPUF-0.286 is 756.9 Pa, lower than that of LFPUF (996.8 Pa), demonstrating good comfort. Moreover, the resiliency of SLFPUF-0.286 is 9.67 %, exhibiting a shape memory property, which has potential applications in the production of functional products with low resilience.