Polyvinyl alcohol (PVA) film
DATE：2019/6/26 9:45:34 / READ： / SOURCE：This station
Polyvinyl alcohol (PVA) film
Overview
Compared with other films, PVA films have significant differences in physicochemical properties, especially because of their excellent gas barrier properties, transparency, gloss, non-chargeability, toughness, organic solvent resistance, and water solubility. It can meet various performance requirements of various industries for film, and is widely used in packaging, demoulding, optics, water solubility and so on.
The industrial production of polyvinyl alcohol is generally obtained by polymerizing vinyl acetate into polyvinyl acetate and then alcoholating polyvinyl acetate.
The physicochemical properties of polyvinyl alcohol are significantly different depending on the degree of saponification and degree of polymerization. The solubility of PVA in water depends entirely on the degree of alcoholysis and degree of polymerization, especially the degree of alcoholysis. PVA is roughly divided into the following four types:
1 completely saponified alcoholysis PVA (simple polymer);
2 part alcoholysis PVA (PVA and polyvinyl acetate mixture);
3 ethylene-vinyl alcohol copolymer (PVA and ethylene copolymer);
4 modified PVA (copolymerized with other substances).
Vinyl alcohol is a polymer containing many hydrophilic hydroxyl groups. Due to the presence of hydroxyl groups, intermolecular and intramolecular hydroxyl groups are easily acetoxy groups. Although hydrophobic, they can cause adjacent hydroxyl groups to be intermolecular or intramolecular. The tendency to synthesize hydrogen bonds is weakened, and a certain amount of acetoxy groups are present to improve the solubility of PVA in water. Therefore, for PVA film for packaging, the selected plastic should be PVA with high alcoholysis, high crystallinity and poorly soluble in water; and water-soluble film should be low alcoholysis, low crystallinity and soluble. Water PVA.
Polyvinyl alcohol produced in China began to be mainly used for synthetic fibers, and subsequently developed for coatings and the like. With the special requirements of packaging for film barrier properties, transparency and water solubility, polyvinyl alcohol film was developed.
Overview
Compared with other films, PVA films have significant differences in physicochemical properties, especially because of their excellent gas barrier properties, transparency, gloss, non-chargeability, toughness, organic solvent resistance, and water solubility. It can meet various performance requirements of various industries for film, and is widely used in packaging, demoulding, optics, water solubility and so on.
The industrial production of polyvinyl alcohol is generally obtained by polymerizing vinyl acetate into polyvinyl acetate and then alcoholating polyvinyl acetate.
The physicochemical properties of polyvinyl alcohol are significantly different depending on the degree of saponification and degree of polymerization. The solubility of PVA in water depends entirely on the degree of alcoholysis and degree of polymerization, especially the degree of alcoholysis. PVA is roughly divided into the following four types:
1 completely saponified alcoholysis PVA (simple polymer);
2 part alcoholysis PVA (PVA and polyvinyl acetate mixture);
3 ethylene-vinyl alcohol copolymer (PVA and ethylene copolymer);
4 modified PVA (copolymerized with other substances).
Vinyl alcohol is a polymer containing many hydrophilic hydroxyl groups. Due to the presence of hydroxyl groups, intermolecular and intramolecular hydroxyl groups are easily acetoxy groups. Although hydrophobic, they can cause adjacent hydroxyl groups to be intermolecular or intramolecular. The tendency to synthesize hydrogen bonds is weakened, and a certain amount of acetoxy groups are present to improve the solubility of PVA in water. Therefore, for PVA film for packaging, the selected plastic should be PVA with high alcoholysis, high crystallinity and poorly soluble in water; and water-soluble film should be low alcoholysis, low crystallinity and soluble. Water PVA.
Polyvinyl alcohol produced in China began to be mainly used for synthetic fibers, and subsequently developed for coatings and the like. With the special requirements of packaging for film barrier properties, transparency and water solubility, polyvinyl alcohol film was developed.
Author：admin