PVA 99 - Polyvinyl Alcohol

About This Product

Polyvinyl alcohol with a degree of hydrolysis near 99 percent, CAS number 9002-89-5, is supplied as a white granule or powder. It is produced in the same way as the 88 percent grade but with hydrolysis taken almost to completion. Removing nearly all the acetate groups leaves a regular chain of hydroxyls that hydrogen-bond strongly to one another, so the polymer develops substantial crystallinity. The consequences run in both directions. It will not dissolve in cold water and must be heated to around 90 degrees Celsius to go into solution, which rules it out for water-soluble film and cold-mix applications. In exchange, films cast from it are stronger, tougher, less permeable to oxygen and markedly more resistant to oils, greases and organic solvents than films from the partially hydrolysed grade, because a solvent cannot penetrate the crystalline regions. That makes it the grade for barrier coatings, for release films used in composite moulding where solvent and resin contact is constant, for textile warp sizing that must survive weaving, and for polarising film in LCD manufacture. It is used in barrier and release films, textile warp sizing, paper coating, polarising film, adhesives and as a mould release. Bio Green Chem supplies PVA 99 to specification on degree of hydrolysis, viscosity, ash, volatiles, pH and particle size.