S. H. Jiang, Z. Gui, Y. Q. Shi, K. Q. Zhou, B. H. Yuan, C. L. Bao, S. M. Lo and Y. Hu (2014) Bismuth subcarbonate nanoplates for thermal stability, fire retardancy and smoke suppression applications in polymers: A new strategy. Journal/Polymer Degradation And Stability 107 1-9. [In English]
Web link: http://dx.doi.org/10.1016/j.polymdegradstab.2014.04.027
Keywords: (BiO)(2)CO3 center dot xH(2)O nanoplates; Catalytic charring effect; Thermal decomposition; Thermal stability; Flame retardancy; Smoke; suppression; LAYERED DOUBLE HYDROXIDE; REDUCED FLAMMABILITY; FLAME RETARDANCY; NANOCOMPOSITES; DECOMPOSITION; DEGRADATION; MORPHOLOGY; TOXICITY; ANTIMONY; IMPACT

Abstract: Bismuth subcarbonate ((BiO)(2)CO3 center dot xH(2)O) nanoplate, a bismuth-containing layered nanomaterial, is successfully applied in improving fire safety properties of polymers for the first time. The introduction of (BiO)(2)CO3 center dot xH(2)O (<= 6.2 wt%) into poly(methyl methacrylate) (PMMA) matrix by in situ polymerization method enhances the thermal stability, flame retardancy and smoke suppression properties remarkably including increased onset degradation temperature (T-0.1, by 58 degrees C) and mid-point degradation temperature (T-0.5, by 24 degrees C), and decreased peak heat release rate, total heat release, toxic volatile organic products (VOP) and smoke density. Morphological studies of PMMA/(BiO)(2)CO3 center dot xH(2)O nanoplate composites by Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) suggest that (BiO)(2)CO3 center dot xH(2)O nanoplates are well dispersed in the PMMA matrix. Thermal decomposition behaviors investigated by Thermogravimetric analysis (TGA) and char analysis studied by Fourier transform infrared spectra (FTIR) demonstrate the catalytic charring effect of (BiO)(2)CO3 center dot xH(2)O to PMMA matrix. Due to the char formation during degradation, the toxic VOP amount and smoke evolution from PMMA combustion are reduced. Meanwhile, thermal decomposition of (BiO)(2)CO3 center dot xH(2)O can release carbon dioxide (CO2) and water, which was evidenced by thermogravimetric analysis/infrared spectrometry (TGA-IR) results. The (BiO)(2)CO3 center dot xH(2)O nanoplates combines several flame-retardant strategies including the char formation, dilution effect of CO2 and water, and physical barrier effect, and thus enhance the thermal stability, flame retardancy and smoke suppression of PMMA/(BiO)(2)CO3 center dot xH(2)O composites simultaneously. (C) 2014 Published by Elsevier Ltd.