Modification of ramie fabric with a metal-ion-doped flame-retardant coating

Transition-metal-ion-doped flame-retardant coatings were constructed on the surface of ramie fabrics by a layer-by-layer (LbL) assembly technique to investigate possible cooperative actions that could improve the fabric's flame-retardant efficiency. We found that these functional coatings, consisting of poly(vinylphosphonic acid) (the anionic layer) and branched polyethylenimine/cupric or zinc ions (the cationic layer), improved the fire retardancy of the ramie fabrics remarkably. Attenuated total reflectance-Fourier transform infrared (FTIR) spectroscopy and energy dispersive X-ray spectroscopy demonstrated the successful LbL assembly process and the incorporation of metal ions into the coating. Thermogravimetric analysis coupled with FTIR spectrometry, vertical flame testing, and microscale combustion calorimetry confirmed the improved thermal stability and reduced flammability of the coated ramie fabrics. All of the results show that the metal-ion-doped flame-retardant coatings not only dramatically increased the residues but also retained the original weave structure and fiber morphology of ramie fabrics well. The enhanced flame-retardant efficiency may have been caused by the lower decomposition temperature of the flame-retardant coating, as promoted by cupric and zinc ions, and as a result, may have helped the flame-retardant activity to take place earlier. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013