The Synthesis And Characterize Of Zinc And Boron Composite Oxides

Flame retardants are an important kind of industrial production additives, their amount is the second largest in the world, which is after the plasticizer. Today, with the increasing of the consciousness of safety and environmental protection, flame retardant additives are demanded to be more efficient and environment-friendly in the future. As a kind of highly efficient and environment-friendly flame retardant additives, zinc and boron composite oxides are known as fire retardant synergist, anti-drip agent, smoke and afterglow suppressant, char promoter and antibacterial agent. Also, they are low cost and non-toxic. Hence, zinc and boron composite oxides can be widely used in many materials to improve their flame retardant performances, these materials include epoxy resin, polyethylene, ethylene-vinyl acetate copolymer, polybutylece terephthalate, polyamide, polyphenylene oxide, unsaturated polyester, acrylate etc.In this paper, the researches of the industrial synthetical methods, the adjustment of composition and ratios of raw materials, the control of particle sizes and morphologies of zinc and boron composite oxides were carried out systematically. The detailed works are listed as follows:1. Six kinds of zinc and boron composite oxides,2ZnO·3B2O3·7H2O,2ZnO·3B2O3·3.5H2O, 2ZnO·2B2O3·3H2O,4ZnO·B2O3·H2O,2ZnO·3B2O3 and 4ZnO·B2O3, were synthesized, using ZnSO4·7H2O、ZnO、H3BO3、Na2B4O7·10H2O、NH4HB4O7·3H2O、NaOH、H2SO4 and NH3·H2O as raw materials. The synthetical routes were designed, which were suitable for industrial production. The samples were characterized by chemical titration, X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and particle size distribution. The yields were also calculated.2. Zinc and boron composite oxides were synthesized on control with different morphologies and particle size distributions. The morpholgies of obtained 2ZnO·3B2O3·7H2O samples were tetragonal-dipyramidal, square sheet and irregular shaped. Their particle size distributions were very uniform. The 2ZnO·3B2O3·7H2O sample obtained by NH3·H2O, ZnSO4·7H2O and H3BO3 as raw materials was single crystal. Seven kinds of 2ZnO·3B2O3·3.5H2O samples were synthesized with different particle size distributions, their morphologies were ruleless-, prismy-, sheet-, pinpoint-and clubbed-shapes. From the point of synthetic methods and reagents and their combined orders, the possible growth and formation mechanisms of diverse 2ZnO·3B2O3·3.5H2O were discussed.Micro/nano single crystals of 2ZnO·2B2O3·3H2O were successfully synthesized on a large-scale. These 2ZnO·2B2O3·3H2O micro/nano single crystals were well monodisperse with the particle size of about 500nm and their morphologies were rhombohedral. The effect of char promotion in the use of synergistic mixture of the 2ZnO·2B2O3·3H2O micro/nano single crystals together with ammonium polyphosphate in polypropylene has also been studied.4ZnO·B2O3·H2O nano-crystalline rods were successfully prepared on a large scale via a one-step method without template. The nano-crystalline rods well dispersed with 70～200 nm in width,6～7μm in length and 20 nm in thickness, and display aspect ratios up to 50～100. With the reaction times increasing, these nano-crystalline rods gradually reunited to form micro-spheres.Anhydrous zinc and boron composite oxides,2ZnO·3B2O3 and 4ZnO·B2O3, were synthesized on a large-scale without any additives respectively. The morphology of 2ZnO·3B2O3 was tetragonal-dipyramidal, and 4ZnO·B2O3 was micro-spheres or nano-rods. The influence of different calcined temperatures on the control of morphology was also studied. The morphologies of 2ZnO·3B2O3 and 4ZnO·B2O3 samples were mainly controlled by which of their precursors.3. Under different reaction temperatures and times, zinc and boron composite oxides with diverse morphologies and different particle size distributions were successfully synthesized by adjust the compositions and ratios of raw materials. The study demonstrated that synthetical methods, including synthetical routes, compositions and ratios of raw materials, were crucial to the morphologies control of zinc and boron composite oxides. The formation mechanisms of zinc and boron composite oxides with different morphologies were briefly discussed.4. The selected synthetical methods were facile with high yields and recycled by-products, which were environment-friendly and accepted for green chemical synthesis.