Just heating and magnetic stirring @90deg. also won't help much in dissolving, even keeping for more than 12 hours.
I have found many references, where they dissolve PVA at this temperature (even higher).
The difficulty is because, its 99+% hydrolyzed and molecular weight is high, i.e, 130,000.
Poly(vinyl alcohol) exhibits lower critical solution temperature (LCST). For those polymers that exhibits LCST, the material is soluble in solvents below LCST temperature rather than the above for usual solubility characteristics of the majority of materials such as sugar in water which dissolves more in hot water. Thus, you can add the polymer in cold water rather than hot water. In hot water, the polymer softens but lamps instead of dissolving. Expectedly, the solubility characteristics depends on the content of the alcohol in the side chain. As poly(vinyl alcohol) cannot be synthesized by simply polymerizing vinyl alcohol due to the tautomer formation, they usually first polymerize blocked monomer, and upon polymer formation, they unblock the side chains. Thus, the degree of unblocking strongly influences the solubility characteristics. You should first check what kind of poly(vinyl alcohol) you have.
I have test in before and I think you can dissolve PVA with high Mw (145000) and degree of hydrolysis (+99%) by adding step by step PVA to hot water (95 degree of centigrade) on magnetic stirrer (450 rpm). First start dissolving, by adding 5%wt PVA to water that heats up and after dissolving this amount, little by little add more amount of PVA. Continuing this procedure for dissolving up to 20%wt PVA, is taking just 2.5 hour.
Sonam Zangpo Bhutia
Add it slowly in cold water under mixing. Heated to 90 degrees Celsius for 30 minutes under mixing. Cool the solution, weigh it and add any water lost during heating. This procedure dissolves all the grades of PVA. More informations here: udated link
https://www.researchgate.net/publication/342785932_Novel_polyvinyl_alcohol_nanofiltration_membrane_modified_with_dopamine_coated_anatase_TiO2_core_shell_nanoparticles
I was also facing problem in my research. Thank you Faiz Khalid!
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