Zinc stearate is a white powder, insoluble in water, soluble in heat It contains organic solvents such as ethanol, benzene, toluene, and turpentine; it decomposes into stearic acid and corresponding salts when exposed to acids; it is a fire hazard under dry conditions, with an auto-ignition point of 900°C; it is hygroscopic. It is understood that zinc stearate is mainly used as a lubricant and release agent for styrene resin, phenolic resin, and amine resin. At the same time, it also has the functions of vulcanization activator and softener in rubber.
The determination method of zinc stearate contentis as follows:
Accurately weigh about 1g of this product, add 50ml of 0.05mo1/L sulfuric acid solution, and boil for at least 10 minutes until the oil layer is clear. If necessary, add water to the initial volume.
Let cool, filter, and wash the filter and beaker with water until the washing liquid is no longer acidic to blue litmus paper; combine the filtrate and washing liquid, add ammonia-gasified ammonium buffer (take gasified ammonium 6.75g, add water to dissolve, add 57ml of concentrated ammonia solution, add water to dilute to 100ml) 15ml and a little chrome black T indicator, heat to 40°C, titrate with disodium ethylenediaminetetraacetate titrant (0.05mol/L) until the solution appears pure blue.
Each 1ml of disodium ethylenediaminetetraacetate titrant (0.05mol/L) is equivalent to 4.069mg of ZnO.
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