The properties:
1. The PVA solvent is water, but its water solubility is greatly affected by the degree of polymerization of influence, especially controlled by the alcoholysis degree. Complete alcoholysis PVA dissolved in the minimal water, when the degree of alcoholysis is under 88 %, and when the temperature is under 20 ℃, it almost completely dissolved, but with the rise of the alcoholsis degree, the solubility of it is reduce greatly.
2. The viscosity of high degree of alcoholysis of Polyvinyl Alcohol water solution change by the different placing conditions, and the storage temperature directly affect the viscosity. Experiments show that when the temperature is between 20 to 50 ℃, the viscosity decrease a lot, and when the temperature is at 50 ℃, the decrease of viscosity is smaller, and when the temperature is more than 80 ℃, the viscosity is stable. The viscosity of PVA solution increases with the increase of the concentration of PVA. The surface of PVA solution crusts easily under stationary state, the crust phenomenon on the coating is extremely unfavorable.
3. PVA film has excellent oxygen barrier properties in dry conditions, oxygen permeation coefficient of it is the lowest in all kinds of resin film. The existence of a large number of hydroxyl (OH) groups on the molecular chain of PVA, in a wet environment, these hydroxyl groups and water molecules form hydrogen bonds, leading to PVA aggregation structure changes, the barrier property of PVA greatly decreased. And with the rise of relative humidity the amount of oxygen through also increase significantly.
4. PVA film in water has the phenomenon of swelling and shedding, if the composite coating film exposed in the moist environment, the high oxygen barrier property will be lost.
The applications:
In China, we often call polyvinyl alcohol fiber as Whalen or Vinylon. Vinylon is seldom directly as garment fiber. The application of it can be in industry, agriculture, fishery, flying transport and medical aspects of expanding. Its main use is as following:
1. Fiber reinforced materials: it can be used as the reinforced material plastic and cement and ceramics and so on. Especially as a carcinogen substance-Asbestos Substitutes, great attention of asbestos board has been heavily promoted by the construction industry.
2. Fishing nets: using Vinylon fracture strength impact strength and corrosion resistance to sea water has excellent strengths of Vinylon, the fracture strength, manufacturing various types of fishing nets, fishing gear and fishing line.
3. Ropes: Vinylon rope is lightweight, wearable, not easy to kink, has good anti impact strength, good weatherability and corrosion resistance to sea water. It can be widely used in aquatic vehicles, aircraft, ships and transport and so on.
4. Canvas: Vinylon canvas strength is good, flying is light, it has good wear resistance and good weather resistance. It has many applications in the transportation, storage, construction, agriculture and forestry.
5. In addition, Vinylon can also be used in the production of packaging materials, nonwoven fiber material and geotextile and so on.