Flame retardant and mechanical properties of expandable graphite/polyurethane foam composites containing iron phosphonate dopamine‐coated cellulose

Abstract

AbstractAdditive‐type flame retardants used in polyurethane foams (PUFs) have low compatibility with the matrix and have a large particle size which reduces the mechanical strength. To overcome this, cellulose‐based additive‐type flame retardants were prepared. Microcrystalline cellulose (MCC) was grinded to a suitable size to be applying as a reinforcement for urethane foam. The ground MCC was coated with the mussel‐derived adhesive protein, dopamine, and formed the iron phosphonate coordination network on the surface. It was confirmed that the modification proceeded well by structural analysis by Fourier‐transform infrared spectrometer and morphology analysis by scanning electron microscope. In the synthesis of PUF, expandable graphite (EG) was added to obtain high flame retardancy. The PUF mixed with 3 wt% of ground MCC‐based flame retardant and 12 wt% of EG (GCF3) was found to have an excellent limiting oxygen index (LOI) of 25.3%, while the LOI of pure PUF was 19.3%. In particular, the compressive strength of GCF3 was remarkably enhanced (21 wt%) compared with the PUF containing 15 wt% of EG. This study produced a new additive‐type flame retardant to improve mechanical strength. This provides a simple and comprehensive solution for PUF applications requiring high flame retardancy and mechanical strength.