The “wanwei” brand polyvinyl alcohol (PVA) series products produced by Anhui wanwei high tech materials Co., Ltd. are made by using advanced technology and process. First, vinyl acetate produced by calcium carbide acetylene method is used as raw material; second, vinyl acetate is produced from biological alcohol, methanol is used as raw material, azodiisobutyronitrile is used as initiator, and is made through polymerization, alcoholysis and other processes.
The appearance is white flake, granular or powdery solid (low alkali alcoholysis process) or white flocculent solid (high alkali alcoholysis process). Specific gravity: 1.23-1.31g/cm3, sheet PVA filling specific gravity: 0.42-0.52g/cm3, flocculent PVA filling specific gravity: 0.20-0.27g/cm3.
The structural formula of PVA is – [CH2CH (OH)] n -, where n represents the average degree of polymerization. The basic properties of PVA are determined by its average degree of polymerization and alcoholysis, but there are more than 10 kinds of irregular structures in PVA molecules, which also have a great impact on its properties.
(1) Water solubility: PVA molecule is very soluble in water because it contains a large number of hydroxyl groups. Its solubility increases with the increase of water temperature. It only expands in cold water (low alcoholysis products can be slowly dissolved in normal temperature water), and can be completely dissolved in hot water. Its aqueous solution has good film-forming and adhesion.
(2) Thermal stability: this series of products soften when heated, and there is no significant change below 40 ℃. When heated for a long time above 160 ℃, they will gradually color, decompose above 220 ℃, and produce water, acetic acid, acetaldehyde and butyraldehyde.
(3) Chemical resistance: this series of products are hardly affected by weak acid, weak alkali or organic solvent, and have high oil resistance.
(4) Storage stability: this series of products have good stability and will not become moldy, deteriorate or hygroscopic after long-term storage in natural dry state.
(5) PVA is a kind of high molecular polymer with secondary hydroxyl group. The secondary hydroxyl group in PVA molecular formula has high activity and can be carried out
Low molecular alcohol is similar to typical chemical reactions, such as esterification, etherification, acetalization, etc. it also reacts with many inorganic and organic compounds. It is non-toxic to humans and animals and can be degraded naturally. It is called green product.
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It is mainly used as medicine film, external medicine base material, water soluble film, high count, high density sizing material, photosensitive film for flat screen printing, paper making, emulsion, etc.
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