Dehydration, Water Vapor Adsorption and Desorption Behavior of Zn[B3O3(OH)(5)] center dot H2O and Zn[B3O4(OH)(3)]

The dehydration behaviors of two different hydrated zinc borate species, Zn[B3O3(OH)(5)] center dot H2O and Zn[B3O4(OH)(3)], which are industrially important flame retardants, were studied by thermal gravimetric(TG) analysis and in situ diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. Dehydration onset temperatures of Zn[B3O3(OH)(5)] center dot H2O and Zn[B3O4(OH)(3)] were 129 and 320 degrees C, respectively, at a 10 degrees C/min ramp rate. A very small amount of boric acid was volatilized in addition to water vapor when both samples were heated at 250 degrees C. A significant amount of water vapor was adsorbed by Zn[B3O3(OH)(5)] center dot H2O from air at 25 degrees C. However, Zn[B3O4(OH)(3)] adsorbed a very small amount of water under the same conditions. Both zinc borates did not have a tendency to cake during storage.