Preparation and thermodynamic characterization of 2CaO·B2O3·H2O nanomaterials with enhanced flame retardant properties

Calcium borate 2CaO·B2O3·H2O nanoflake and nanobelt have been prepared under hydrothermal conditions, which were characterized by the XRD (X-ray diffraction), FT-IR (Fourier transform infrared spectroscopy), TGA (thermogravimetric analysis), SEM (scanning electron microscope) and TEM (transmission electron microscope). Their thermodynamic parameters were also obtained by calorimetry method through an appropriate thermochemical cycle, showing that their thermal stabilities decreased gradually with the decrease of 2CaO·B2O3·H2O sizes. The flame retardant properties of the prepared 2CaO·B2O3·H2O nanomaterials were investigated by a non-isothermal decomposition kinetic method and limited oxygen index method. With the decrease of TG mass loss, the decrease of heat release for DSC, the increase of LOI values, and the increase of apparent activation energy Ea, the flame retardant properties of prepared 2CaO·B2O3·H2O samples are increased gradually from non-nanostructure to nanobelts then to nanoflakes, which may be ascribed to their sizes being decreased accordingly. The possible flame retarding mechanism has been proposed. It can be predicted that 2CaO·B2O3·H2O nanoflakes could serve as a potential flame retardant.