Use of polyvinyl alcohol and its gel boiling method

Polyvinyl alcohol polymer is a kind of water-soluble polymer obtained by hydrolysis of polyvinyl acetate instead of monomer polymerization. It is soluble in glycerol at 120 ~ L50 ℃, but becomes a jelly when it is cold to room temperature. Polyvinyl alcohol dissolution step: to dissolve polyvinyl alcohol, add the material into room temperature water under stirring, disperse evenly, and then heat up to accelerate dissolution.

The use of polyvinyl alcohol of each brand shows that the viscosity of PVA17-88 aqueous solution gradually increases with time at room temperature. However, when the concentration is 8%, the viscosity 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 silica than PVA17-88. 0.1% borax of the solution mass will make 5% pva17-99 aqueous solution gel, while the amount of borax that causes gel of the same concentration PVA17-88 aqueous solution needs 1%. Polyvinyl alcohol 1799b is mainly used to manufacture high viscosity polyvinyl butyral. It is widely used as a dispersant of sizing materials.

In addition, polyvinyl alcohol has various typical reactions of secondary hydroxyl compounds, such as esterification. Degraded in strong acid, softened or dissolved in weak acid and weak base. High concentration polyvinyl alcohol is incompatible with inorganic salts, especially sulfate and phosphate. Phosphate can precipitate 5% (w/v) polyvinyl alcohol. Borax can react with polyvinyl alcohol solution to form gel.

Polyvinyl alcohol is a good glue solution, which can replace most industrial glues. How to boil polyvinyl alcohol glue solution? First, prepare several polyvinyl alcohol, 1000 ml beaker, glass plate, electric stove, and a stainless steel basin (the caliber is between 30-40cm). After preparation, take 50-80 grams of polyvinyl alcohol and put it into the beaker. Add 900-1000 ml of normal temperature water to the beaker and stir it evenly with a glass rod. The water should not be too full. It is better to be 2-3cm away from the beaker mouth. If it is too full, it will overflow when heated for a while. Put the beaker into the stainless steel basin, add normal temperature water into the stainless steel basin, and it is advisable to submerge the beaker to a depth of 2/3 of the height. Put the stainless steel basin on the electric stove to heat and stir while heating. After the solid polyvinyl alcohol is completely dissolved, take out the beaker (be careful of scalding), and cool it to room temperature for standby. Be careful of electric leakage to avoid electric shock. Caution: Hot. Fully stir during heating to avoid pimples.