Chemical Properties
Abbreviation: PVDF, a polymer compound made of polyvinyl alcohol and formaldehyde. Slightly straw yellow solid. Thermoplastic. Density 1.2. Density 1.2, softening point about 190℃. Thermal deformation temperature 65～75℃. Water absorption about 1%. Soluble in acetone, chlorinated hydrocarbons, acetic acid, phenols. Mainly used in the manufacture of wear-resistant high-strength enameled wire coating and metal, wood, rubber, glass adhesive between laminated plastics, as the intermediate layer of laminated plastics and the manufacture of high impact strength, compression modulus of elasticity of foam.
Uses
It is used in the anomalous sorption and pervaporation of aqueous organic mixtures by poly(vinyl acetal) membranes. Poly(vinyl formal) is mainly used in three general applications wire coatings, surface coatings and adhesives. The first and extensive application of poly(vinyl formal) is in the manufacture of a tough, adhesive and heat resistant wire enamel.
Preparation
Poly(vinyl formal) was developed by General Electric as a wire coating and the early process involved direct reaction of a mixture of poly(vinyl acetate), glacial acetic acid, formalin and concentrated sulfuric acid at 70°C. After the desired degree of polymerization is obtained, ammonium hydroxide is added to bring the pH to about 9-10. The reaction mixture is poured into water to precipitate the poly(vinyl formal). Poly(vinyl formais) have also been used as fibers.
