Increase the temperature to 90-100 deg C and heat for 2 hours that would give clear and transparent solution of PVA.

90  deg C water; stirring; 2h. 

Dear all,

beside the aforementioned suggestions, better to use a heavy magnetic stirring bar with ring (at the middle) or a mechanical stirrer. Reduce the concentration or start dissolving with low concentration till you reach your 10%. However, 90 and 100 °C are too high, so besides the inevitable mechanical degradation of thick solution, thermal degradation may also occurs at these temperatures. Regards

You have to use a mechanical stirrer and if you want to avoid water evaporation and keep the initial concentration of PVA, you have to employ a reactor provided with a condenser. With respect to the temperature, you have to heat the system. The  temperature usually used is 90 °C or 100 °C. You can try to employ a temperature lower than 90 °C, but it can take long time to dissolve the PVA.

To avoid degradation it is better to use first low temp., a then heat it over night at 50-60 C and then if neccessary go to  higher. temp.

Helena

Depending on the mol wt of the PVA, the higher mol wt PVA could have very low solubility in water. I usually dissolve PVA at room temperature first using mechanical stirrer at high speed, around 80-90% of PVA powder will dissolve in water in around 30 mins, then the pva solution is continue to stir at lower speed at 70C in water bath for 1 hour. the PVA that I used is partially hydrolyzed PVA, molecular weight between 26,300 – 30,000. i dissolve the same PVA concentration, 10% of PVA.

The polyvinyl alcohol powder will need to be dissolved in water and that takes some heating (80-90°C)

The most effecive way to dissolve PVAl is to use autoclave. To prevent aggregation one should keep the solution in elevated temperature (at least 40 C).

If you are starting with a highly hydrolysed pva say 98-99%, you may wet it first by stirring in cold water for about 30 minutes then raise the temperature to 95 degrees Celsius, it should dissolve in about 30 minutes. If you do not stir continuously, you are likely to form a hydrogel but even that can be dissolved if you raise the temperature to about 150 degree Celcius.

Please find attached files. These articles might be helpful.

100 degree C for 60-80 min is on stirring condition is enough for proper solubilization 

PVA is polymer synthesized from Polyvinyl acetate. The degree of hydrolysis is important parameter for its solubility.

Thank you very much. But as I know so far, it is better to avoid from evaporation at 100 degree, I need to control the amount of water included due to the certain density calculation and so on. I tried not to exceed 90-95 degrees basically. I just cannot be sure about its homogeneity during the stirring. It is Sigma 363146, 99+% hydrolyzed one.

It depends on moleculra weight - it means time and temperature. From my experience with very high Mw it results that first I am applying room temp. for 24 hours- the sample swells very much, Then I am increasing temp. to around 50-60C and I am waiting, observing carefully the time of making good solution. Very often on the bottom there is left very small amount of unsoluble sample - some times it is even to see it.. Then if you need the data for calculation -  you should filter it and weight. I would advice to filter the solution even if you almost do not see anything as unsoluble part is very transparent .Check molecular weight and may be ask the producer. I was working with Moviol. Good luck

Helena Janik, Gdansk University of Technology, PL

Good luck.

i tried all the above recommendations but PVA did not dissolve at all , do you know if there is any certain chemical can be add to increase the dissolvability

Hi,Luma

I just happened to the issue when I was doing insitu hybrid .If you are using the magnetic stirrer on the "85 °C" machine ,the actual temperature maybe just 60°C or less.sevaral days ago I just tried to put the 10% PVA（10ug PVA in the 100ml dd H2O dissolving in the glass bottle ) into the  80°C oven for 4h,it was dissolved.hope it will help some.

Hi Luma

It is better to characterize the PVA first and match your pattern with the known system of PVA in literature

thanks Guofu Zhu     you were right after I raise the temperature to above 110C the PVA dissolved in water many thanks pro

http://www.silverson.com/us/resource-library/application-reports/preparation-of-polyvinyl-alcohol-pva-solutions/

Thanks for above the comments. Anyone had safety issues handling granula PVA.

Thank-you so much for the information to all.

Put it in the refrigerator.

Yes, it works. People don't believe me until I show them.

It's basic polymer chemistry and thermodynamics.

Just today I prepared 5%w/w solutions of PVA 31K, PVP 10K and 360K, Pluronic 6K and 2K, and polysorbate 80 this way. All were fully dissolved in three hours.

Put the solution without stirrer? John Francis Miller

Yes - just take it out and shake occasionally. Higher molecular weight material will take longer and require more occasional shaking.

The solubility of PVA depends on Molecular weight. So can can manipulate the temp. and concentration to dissolve it but you have to be sometimes very patient.

Regards Helena Janik. Gdansk University of Technology.

In our laboratory we simply use a Vorwerk Thermomix device. As easy as cooking! Efficient mixer. You can increase the desired temperature for a while. The concentration of PVA solutions will depend on their molecular weight and level of hydrolysis.

Suppose If we dissolve some protein drug in PVA how to analyze its time of releasing the protein. I am searching for a media which melts the PVA and dissolves the protein drug for timely release of protein analysis. Can any one suggest some such that the media shouldn't degrade the protein present and at the same should dissolve PVA matrix.

i just raise temperature up to 90-95C

First, heat the water up to 80°C. When the water is heated up, put the PVA slowly (don't put all the powder altogether). Keep the solution heated until it's done. It should not take much time if you do it this way. Make sure the water is not evaporating, otherwise, you will have the wrong concentration.

For whom it may be useful: I was dealing with the same problem and here is what I did a few hours ago and it worked. I first stirred the PVA grains with cold water at room temperature for 30 min. Then I put most of the water aside and placed the beaker containing rest of the PVA and water mixture inside a 90°C bath and started stirring at 400 rpm. I kept stirring for 15 min and already all the grains were gone and only a viscous mixture full of bubbles. I added the rest of the water slowly in small amounts and after 1 hour of stirring I had a nice clear mixture. The "water" actually contained 40% ethylene glycol, but it should work with plain water as well.