Layer-by-Layer Self-assembly of Organic-inorganic Hybrid Intumescent Flame Retardant on Cotton Fabrics

In this study, a novel organic-inorganic hybrid intumescent flame-retardant composed of nanosilica (SiO2) covered with polyethyleneimine (PEI) and phytic acid (PA) was coated on cotton fabrics by layer-by-layer (LbL) self-assembly to improve flame retardancy of cotton fabrics. FT-IR, SEM and EDX were used to characterize the deposition of SiO2-PEI/PA on the surface of cotton fabrics. The LbL assembly process had a minor effect on the tensile strength of cotton fabrics. With the synergistic effect of phosphorus, nitrogen and silicon, the coated cotton fabrics with only 7 bilayers exhibited excellent flame retardancy with an LOI value of 33.7 % and a char length of 7.5 cm. TG analysis results showed that cotton/(SiO2-PEI/PA)(7) had 40.7 % char residue at 600 degrees C, compared with 8 % char residue of uncoated cotton fabrics. Cone calorimetry test confirmed that cotton/(SiO2-PEI/PA)(7) displayed a major reduction in peak of heat release rate (pHRR) of 75 % and total heat release (THR) of 52 %.