It softens and decomposes at 200℃. Due to the presence of various acetyl group residues in the product, it has different viscosities and properties. It is soluble in water but insoluble in petroleum solvents. Polyvinyl alcohol is a white granular water-soluble synthetic resin. Its chemical name is Polyvinyl alcohol, abbreviated as PVA. The main properties of polyvinyl alcohol are determined by the alcohol degree and polymerization degree of the molecules that constitute the resin. The properties are as follows: ① Water solubility: It is easily soluble in water and insoluble in almost all organic solvents. The dissolution rate increases with the increase of water temperature. ② Viscosity of the aqueous solution: The viscosity of the polyvinyl alcohol aqueous solution is lower than that of other water-soluble polymers. It varies according to the polymerization degree, concentration and temperature. ③ Film-forming property: The aqueous solution of polyvinyl alcohol is easy to form a film. The film has physical properties such as tensile strength and wear resistance, which are superior to other synthetic resins. ④ Hygroscopicity: The hygroscopicity of polyvinyl alcohol is lower than that of other water-soluble polymers, and it is less affected by humidity. ⑤ Resistance to chemicals and oil: It is basically unaffected in weak acids and weak bases. In addition, it also has excellent oil resistance.
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