Preparation, Characterization, and Application of Zinc Borate as a Fire Retardant Agent for Poly(acrylonitrile)

Nowadays, fire retardants are very important. These materials are added to flammable items to increase their resistance to flammability. Zinc borates are an important class of the fire retardants, which have been prepared in this paper using two different precursors. In the first method, tris(ethylenediamine) zinc(II) tetraphenyl borate complex, [Zn(en)3](BPh4)2, was prepared by reaction of ZnCl2 with en ligand in the presence of NaBPh4 in water solvent. The prepared Zn(II) complex was calcined at 650 ºC to obtain zinc borate. In the second method, a mixture of H3BO3/ZnO with a mole ratio of 6:2 was reacted under the hydrothermal operation at 200 ºC, and zinc borate was obtained. The prepared zinc borates were characterized by different methods including FT-IR, XRD, SEM, and TGA. In addition, the application of the prepared zinc borates as a fire retardant was investigated for poly(acrylonitrile) (PAN) polymer. The results show that the addition of zinc borate to PAN increased its resistance to flammability and the combustion process immediately terminated when the sample removed from the flame. Therefore, the prepared zinc borates are good candidates for use as fire retardants in polymers.