Polyvinyl alcohol PVA 1788 sheet; odorless, soluble in water at 60-80°C. Its aqueous solution has good adhesion, film-forming and emulsifying properties; it is resistant to most organic solvents such as oils, lubricants and hydrocarbons; it has chemical properties such as esterification, etherification and acetalization of long-chain polyols.
1. Film-forming property: PVA 1788 is easy to form a film, and its film has excellent mechanical properties. The tensile strength of the film increases with the increase of the degree of polymerization and the degree of alcoholysis.
2. Adhesion: PVA 1788 has good adhesion to hydrophilic cellulose. In general, the higher the degree of polymerization and alcoholysis, the stronger the bond strength.
3. Thermal stability: When the PVA 1788 sheet is heated to about 100 ℃, the appearance changes gradually. The partially alcoholyzed PVA begins to melt at around 190°C and decomposes at 200°C. Complete alcoholysis of PVA begins to melt at about 230°C, and decomposes at 240°C. Thermal cracking experiments show that the lower the degree of polymerization, the faster the weight loss; the higher the degree of alcoholysis, the shorter the decomposition time.