Pretreated cellulose fiber for enhancing fire resistance of flexible polyurethane foam composites with reinforced properties.

To promote environmentally sustainable behavior, it is meaningful to develop a simple preparation method of polyurethane foam (PUF) with excellent performance and degradability. Herein, PUF composites were economically and conveniently synthesized by mixed foaming of polyurethane prepolymer and cellulose nanocrystals (CNCs). After the hydrolysis of dissolving pulp fibers with formic acid (FA), hydrophobic ester groups were introduced in CNCs, thereby increasing the surface hydrophobicity of PUF composites. CNCs acted as a reinforcement agent capable can replace 10% up to 60% prepolymer for foaming, the modified PUF exhibiting gradient morphology structure and enhanced specific mechanical and thermal properties. When the CNCs replacement ratio was 50%, the maximum compressive stress was 1103.19 kPa, which is 21-fold that of the original foam. Remarkably, the addition of CNCs enhanced thermal insulation performance of the prepared foam, which of thermal conductivity decreased from 0.0780 W/mK to 0.0549 W/mK. The upgraded polyurethane foam composites promise to open exciting new windows on producing fire resistance PUF with enhanced performance. [Display omitted] • PUF composites were fabricated by polyurethane prepolymer and CNCs. • Maximum compressive stress reached 1103.19 kPa at 50% replacement rate of CNCs. • Thermal conductivity of foams decreased from 0.0780 W/mK to 0.0549 W/mK. • Sustainable and economically feasible method for producing fire resistance PUF. [ABSTRACT FROM AUTHOR]