Hi, take only 2-5% PVA and add slowly into 100 ml DI water with magnetic stirring. After initial stirring for 10-15 min, stir the solution with heating with T = 80 oC. If PVA still not dissolved in DI water, add 1 ml nitric acid slowly (a drop by drop) into the stirring solution. Hopefully, you will get completely dissolved and transparent solution.

Thank you Ramachandran for your kind suggestion. That really worked. I put 80 C on the hot plate previously. However, the temp of the solution was lesser than that. Today, I increased the temp around 100 and it dissolved. However, I will have to dissolve around 18% PVA. Till now, I have dissolved 10% PVA ( MW: 31000-50000) and 5% PVA ( MW: 60000-75000). Hope that works. Thank you very much for your help again.

To dissolve 99% hydrolyzed medium MW PVA, slowly add it to cool water, then heat the mixture to 90–95°C with vigorous stirring for several hours. Increasing temperature and gradual dispersion help overcome its strong hydrogen bonding and crystallinity.