Polyvinyl alcohol cannot be produced directly by polymerization of the monomer, because the monomeric vinyl alcohol (enol) relocates and stabilizes
immediately under proton excursion to the acetaldehyde (ethanal).
Technically the polyvinyl acetate dissolved in methanol is transformed into polyvinyl alcohol by hydrolysis (alcoholysis). Caustic soda is used as a
The technical application properties depend particularly from the molar mass and from the part of the acetyl groups available in the macromolecule (degree
Polyvinyl alcohol is a crystalline polymer which is branched out insignificantly due to his processing method. The melting point and glass transitions
temperature depends on the hydrolysis degree and the molar mass also still from the distribution of the acetyl groups (statistical or in blocks) the tacticity and the water content of the polymer.
The films made of polyvinyl alcohol are rice-firm and viscous-elastic. They are oil and heat-resistant. As plasticizers can be used polyols, as for example
glycerol and ethylene glycol.
With decreasing degree of polymerization and degree of hydrolysis the solving-rate in water increases. Polyvinyl alcohol can be dissolved by strewing in
water and stirring at 90Â°C.
In dissolved form polyvinyl alcohol must be conserved. The viscosity depends on the molar mass, the degree of hydrolysis, the concentration and the
Through sulphates polyvinyl alcohol solutions can be felled. Boric acid can be set in as thickeners.
Through processing with chromates polyvinyl alcohol becomes insoluble in water.