A new flame retardant nanocoating has been constructed by the alternate adsorption of polyelectrolyte amino-functionalized multiwall carbon nanotube (MWNT-NH2) and ammonium polyphosphate (APP) onto flexible and porous ramie fabric. Scanning electron microscopy indicates that the adsorbed carbon nanotube coating is a randomly oriented and overlapped network structure, which is a promising candidate for flame retardancy applications. Attenuated total reflection Fourier transform infrared spectroscopy and energy-dispersive X-ray analysis confirm that the APP is successfully incorporated into the multilayers sequentially. Assessment of the thermal and flammability properties for the pristine and nanocoated ramie fabrics shows that the thermal stability, flame retardancy and residual char are enhanced as the concentration of MWNT-NH2 suspension and number of deposition cycles increases. The enhancements are mostly attributed to the barrier effect of intumescent network structure, which is composed of MWNT-NH2 and the absorbed APP.

We describe the preparation and characterization of a green and renewable polyelectrolyte complex (PEC) containing phosphorus, nitrogen and carbon elements, based on the ionic complexation between chitosan and phytic acid. Introduction of this PEC to ethylene−vinyl acetate copolymer (EVA) leads to an improvement of the flame retardancy. As for the EVA/PEC composites with 20.0 wt % of PEC (EVA/20PEC), the char residue at 600°C is 12 wt % higher than that of the pristine EVA under nitrogen atmosphere. Compared to the pristine EVA, the peak heat release rate and total heat release of EVA/20PEC show 249 W g −1 and 5.6 kJ g −1 decreases, respectively. The char residue of EVA/20PEC is full and compact, demonstrating excellent intumescent effect. Introduction of this PEC also contributes to a slight increase of the Young's modulus while maintains the excellent ductility. This work provides a new approach for the development of environmentally friendly intumescent flame retardant system.

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Self-extinguishing multilayer coatings consisting of polyelectrolyte polyethylenimine (PEI) and ammonium polyphosphate (APP) have been constructed by the layer-by-layer assembly technique onto flexible and porous ramie fabric. Attenuated total reflection Fourier transform infrared spectroscopy and energy-dispersive X-ray analysis directly confirmed that PEI and APP were successfully incorporated onto the surface of ramie fabric sequentially. Assessment of the thermal and flammability properties for the coated ramie fabrics showed that the char residue at temperatures ranging from 400 to 600 °C during thermogravimetric analysis (TGA) and the self-extinguishing ability during vertical flame test were significantly enhanced as compared with the pristine sample, which showed strong dependency on the number of deposited layers, especially on the concentration collocation of both polyelectrolytes. This work provided a simple but effective method for the controlled formation of self-extinguishing intumescent coating on ramie fabric and can be applied to other cellulose systems.

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In this paper, the thermal stability and fire retardant behavior of epoxy resin (ER) composites filled with graphene nanosheets (GNS) and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) were investigated.

A new polyelectrolyte complex (PEC), containing phosphorus, nitrogen and carbon elements, has been prepared from positively charged polyethylenimine (PEI) and negatively charged phytic acid (PA). The PEC shows good performance in improving the thermo-oxidative stability and flame retardancy of pristine polypropylene (PP). When the content of PEC is 20 wt%, the char residues at 600 C for the PP/ PEC composites (PP/20PEC) are 10 wt% higher than those of pristine PP under an air atmosphere. Meanwhile, the peak heat release rate and total heat release of PP/20PEC are 314 W g À1 and 7.7 kJ g À1 lower than those of pristine PP, respectively. In comparison, PEI or PA is less effective than PEC in improving the thermo-oxidative stability and flame retardancy of pristine PP. Furthermore, the char residues of PP/20PEC are more full and compact, the surfaces of which are covered with a perfect intumescent layer. This work proposes a new guideline for designing and fabricating an intumescent flame retardant system.

Graphene nanosheets and layered double hydroxides showed a synergistic effect on improving the flame retardancy of epoxy resin.