Polyvinyl alcohol is the abbreviation of a water-soluble polymer obtained by hydrolysis of polyvinyl acetate without polymerization of monomers. It is soluble in glycerol at 120～150℃, but becomes jelly when cooled to room temperature. In the dissolving step of polyvinyl alcohol, for dissolving polyvinyl alcohol, the material should be added to room temperature water under stirring, and then heated up to accelerate the dissolution.
The use of each grade of polyvinyl alcohol shows that the viscosity of PVA17-88 aqueous solution increases gradually with time at room temperature. But the viscosity when the concentration is 8% is absolutely stable, polyvinyl alcohol 17-92 is referred to as PVA17-92 for short, PvA17-99 solution is more sensitive to the gel caused by borax than PVA17-88, and the solution quality is 0.1% borax It will make 5% PVA17-99 aqueous solution gel, and the amount of borax that causes the same concentration of PVA17-88 aqueous solution to gel needs to be 1%. Polyvinyl alcohol 1799B is mainly used in the manufacture of high viscosity polyvinyl butyral. Widely used as a dispersant for sizing materials.
In addition, polyvinyl alcohol has various reactions typical of secondary hydroxyl compounds, such as esterification. Degraded in strong acid, softened or dissolved in weak acid and weak base, high concentration of polyvinyl alcohol is incompatible with inorganic salts, especially with sulfate and phosphate, phosphate can make 5% (W/V) polyvinyl alcohol precipitation. Borax can form a gel with polyvinyl alcohol solution.
Polyvinyl alcohol is a good glue and can replace most industrial glues. How to boil polyvinyl alcohol glue? First, prepare some polyvinyl alcohol, a 1000 ml beaker, a glass plate, an electric stove, and a stainless steel basin (a diameter of 30-40cm is appropriate). After preparation, take 50-80 grams of polyvinyl alcohol into a beaker. Add 900-1000 ml of room temperature water to the beaker and stir well with a glass rod. The water should not be too full, preferably 2-3cm away from the mouth of the beaker. If it is too full, it will overflow when heated. Put the beaker into the stainless steel basin, add water at room temperature to the stainless steel basin, and submerge the depth of 2/3 of the height of the beaker. Heat the stainless steel bowl on the electric stove, stirring as it heats. After the solid polyvinyl alcohol is completely dissolved, take out the beaker (be careful of scalding) and cool it to room temperature for later use. Be careful of leakage to avoid electric shock. Be careful of burns. Stir well during heating to avoid lumps.