Polyvinyl alcohol (PVA) is an important chemical raw material, used to make polyvinyl acetal, gasoline-resistant pipes and vinylon synthetic fibers, fabric treatment agents, emulsifiers, paper coatings, adhesives, glues, etc.
Different grades
Polyvinyl alcohol is obtained by hydrolysis of polyvinyl acetate, but not directly by polymerization of vinyl alcohol. Because vinyl alcohol is extremely unstable, it is impossible to have free vinyl alcohol monomers.
Different degree of polymerization
There are generally three kinds of alcoholysis degree, namely 78%, 88%, and 98%. Completely hydrolyzed polyvinyl alcohol is obtained by hydrolyzing polyvinyl acetate with a degree of hydrolysis of 98% to 100%. The degree of hydrolysis of partially hydrolyzed polyvinyl alcohol is generally 87% to 89%. To keep things simple, the numbers for polymerization are usually listed first, followed by the percentage of hydrolysis. So, PVA-1788 (Poval 217) means it has a polymerization degree of 1700 and a hydrolysis degree of 88%.
Different water solubility
PVA-1788 is well soluble in water and can be quickly dissolved in cold water or in boiling water. The viscosity of PVA-2488 (Mowiol 47-88) is 1.5-2 times that of 1788 (different manufacturers' grades). The dissolution process of 2488 is longer than that of 1788, and its tensile force after dissolution is greater than that of 1788.
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