Flame-retardant coating by the layer-by-layer assembly of poly(vinylphosphonic acid) and polyethylenimine for ramie fabric
writer：Wang LL, Zhang T, Yan HQ, Peng M*, Fang ZP, Li Y, Wang H.
keywords：Layer-by-layer assembly; Poly(vinylphosphonic acid); Flame retardant; Ramie fabric
source：期刊
specific source：Chinese J Polym Sci, 2013.4,32(3): 305-314
Issue time：2014年
A novel intumescent flame retardant coating, consisting of poly(vinylphosphonic acid) (PVPA) as the acid source and branched polyethylenimine (BPEI) as the blowing agent, was constructed on the surface of ramie fabric by layer-by-layer (LbL) assembly to remarkably improve the flame retardancy of ramie. The PVPA/BPEI coating on the surface of individual fibers of ramie fabric pyrolyzes to form protective char layer upon heating/burning and improves the flame retardancy of ramie. Thermogravimetric analysis reveals that the PVPA/BPEI-coated ramie fabrics left as much as 25.8 wt% residue at 600 oC, while the control (uncoated) fabric left less than 1.4 wt% residue. Vertical flame test shows that all PVPA/BPEI-coated fabrics have shorter after-flame time, and the residues well preserved the original weave structure and fiber morphology, whereas, the uncoated fabric left only ashes. Microscale combustion calorimetry shows that the PVPA/BPEI coatings greatly reduce the total heat release by as much as 66% and the heat release capacity by 76%, relative to those of the uncoated fabric.