2. Freeze-drying method: freeze-thaw PVA aqueous solution repeatedly at low temperature. After 3 or 4 cycles, PVA forms solid hydrogel under the condition of physical temperature change.
Polyvinyl alcohol: organic compound, white flake, flocculent or powdery solid, tasteless. Soluble in water (above 95℃), slightly soluble in dimethyl sulfoxide, insoluble in gasoline, kerosene and vegetable oil.
Extended data:
Characteristics of polyvinyl alcohol:
The physical properties of 1. are affected by chemical structure, alcoholysis degree and polymerization degree.
2. There are two chemical structures in 2.PVA molecule, namely 1, 3 and 1, 2 glycol structure, but the main structure is 1, 3 glycol structure, namely "head-tail" structure. The polymerization degree of polyvinyl alcohol can be divided into ultra-high polymerization degree (molecular weight 250,000-300,000), high polymerization degree (molecular weight17-220,000), medium polymerization degree (molecular weight12-15,000) and low polymerization degree [25,000-35,000].
3. Emulsion stabilizer for emulsion polymerization of polyvinyl acetate. Used for manufacturing water-soluble adhesives. Used as modifier of starch adhesive. It can also be used to prepare photosensitive adhesives and sealants resistant to benzene solvents. Also used as release agent, dispersant, etc. Store in a cool and dry warehouse. Moisture and fire prevention.
Baidu encyclopedia-polyvinyl alcohol