Study On The Preparation,Modification And Application Of Borate-pillared Hydrotalcites

Hydrotalcite, hydrotalcite-like compounds and intercalated hydrotalcite are collectively referred to as hydrotalcite (LDHs) intercalated materials.Early, the LDHs such as zinc-aluminium-borate LDHs, magnesium-aluminium-borate LDHs and zinc-aluminium-carbonate LDHs, magnesium-aluminium-carbonate LDHs etc are synthesized successfuly. And these LDHs have already been proved that their flame retardancy efficiency are good.And on the basis of previous research work, this paper firstly use calcium nitrate tetrahydrate, aluminum nitrate nanohydrate, sodium hydroxide and boric acid or borax as raw material, through exploring the best synthesis method, the optimum synthesis conditions to successfully synthesise borate-pillared hydrotalcite, and then using surface modification agent and coupling agent to modified it;Finally the modified borate-pillared hydrotalcite is added to EVA, and test the burning oxygen index of composite to explore flame retardant efficiency of borate-pillared hydrotalcite.Specific content is as follows:(1)With calcium nitrate tetrahydrate, aluminum nitrate nanohydrate, sodium hydroxide and boric acid or borax as raw material, firstly adopts the common method-coprecipitation as synthesis method, solutions of boric acid and sodium hydroxide solution were added simultaneously to the mixed salt solution ofnitrate tetrahydrate and aluminum nitrate nanohydrate at room temperature, and then the formation product-milky white slurry was placed in the oil bath which temperature is 65℃ for crystallization, crystallization time is 10 h, after crystallization the slurry was placed in room temperature for 13h.To explore the optimum synthesis method and conditions, change the crystallization temperature and time respectively to synthesize products, and products of different reaction conditions were characterized by XRD, FT-IR, through the analysis found that this method can get borate-pillared hydrotalcites, but there will be a lot of by-products generated at the same time, and the product phase is not very good.Then,using ion exchange method to synthesized borate-pillared hydrotalcites, through the analysis of the FT-IR and XRD characterization results of synthetic product, found that using this method can get more pure borate-pillared hydrotalcites, so ion exchange method is the optimum synthesis method.(2) Using the product which synthesized by the optimum methods and synthesis conditions as the raw material, using stearic acid to modified its surface, adding silane coupling agent for the further surface modification, to improve its compatibility with polymer molecules;Modified products were characterized by XRD, FT-IR, suspension property, activation index test, and when the adding amount of coupling agent was 1% NDZ-311, the activation index can up to 97.86%.The modified powder was added to EVA matrix, and getted the borate-pillared hydrotalcites/EVA composites. The mechanics performance test and the oxygen index test showed that the modification borate-pillared hydrotalcites by 1% NDZ-311 blending with EVA at the ratio of 2:5, the blending composite average tensile strength is 9.68MPa, on average, the elongation at break is 663.3%;Oxygen index is 27.8%;...