Preparation And Performances Of PAV/Mg-Al Double Hydroxides Nano-Composite

Polymers and layered double hydroxides nanocomposites because of its performance in mechanical properties, flame retardancy, thermal stability, and optical performance, etc., to make up for the deficiencies of conventional polymer materials, become a hotspot composite. In this paper, solution blending method and delamination-adsorption preparation of the polyvinyl alcohol/Mg-Al double hydroxides nanocomposite were studied. The composites prepared by the two methods on mechanical properties, flame retardancy and thermal stability were studied and compared. The experimental results show that, the overall performance of composite materials has greatly improved and improved due to the addition of the Mg-Al double hydroxides. The main contents are as follows:1. Preparation of Mg-Al double hydroxide nanomaterials was the use of the co-precipitation method, with the new dropwise.The initial Mg/Al ratio, the pH value of the reaction system and effectiton of Aging crystals on the crystallinity were also discussed. The X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and thermogravimetry (TG) was used to characterize the final product. The results showed that, When the initial Mg/Al ratio is1:1, the crystalline form of the product is not complete, and the degree of crystallinity is poor. However, magnesia double hydroxides nanomaterials can be obtained when the Mg/Al ratio of2to4:1. Products will be accompanied by Mg (OH)2generated in the reaction system pH10.5. When the pH is higher than10.5, with the pH value of the reaction system increases, the better the degree of crystallinity. Aging crystalline conducive to the improvement of product crystallinity. Finally prepared magnesia double hydroxides nano material is thermally stable when below240℃, the laminate structure was also very clear. However, the generation of the infrared absorption peak was caused by the Free water, interlayer between the hydroxyl group and the layer of CO32" and hydrogen bonding.2. Preparation of polyvinyl alcohol/Mg-Al double hydroxides nanocomposites by solution blending, The effecation of magnesia double metal hydroxide added amount, reaction time and the concentration of the aqueous polyvinyl alcohol solution on the synthetic polyvinyl nanocomposites Aluminum Magnesium double metal hydroxide dispersion were investigated. The results showed that, When the added amount of Mg-Al double hydroxides was less than8.5%, Mg-Al double hydroxide can more uniformly dispersed. Extending the reaction time is conducive to the effect of the increase of the dispersion of the Mg-Al double hydroxide, The ideal response time is greater than6h. The lower the concentration of the polyvinylalcohol can get a more uniform thin film of the dispersion.3. Preparation of polyvinyl alcohol/Mg-Al double hydroxides nanocomposites by delamination-adsorption method. The effecation of content of the magnesia double hydroxides on dispersion was investigated, and comparison with solution blending method. The results showed that, The dispersion of Mg-Al double hydroxides in the composite material which prepared by peeling-adsorption method was better than the composite material prepared by the solution blending method, But the reaction system is more complex than the solution blending.4. The mechanical properties, flame retardant properties and thermal stability of polyvinyl alcohol/Mg-Al double hydroxides nanocomposites were studied, and compared the two methods. The results showed that, Magnesium aluminum double hydroxide is added to improve the mechanical properties of the composite, the flame retardant properties were significantly improved and the thermal stability was also improved significantly. Tensile of Composites which synthesized by solution blending and layer away-assay strength than pure polyethylene increased by33.16%and66.84%, respectively. Limiting oxygen index increased62.94%and77.16%, respectively. The initial decomposition temperature can be increased by14.8℃and16.1℃. Temperature of50%weight loss can be increased to38.3℃and40.1℃. Overall performance of polyvinyl alcohol/Mg-Al double hydroxides nanocomposites which synthesized by delamination-assay method superior solution blending.