We need to prepare 500-micron films from PVAc to evaluate the tensile strength. The existence of bubles in the film is not accepted due to stress concentrastion.
I assume that the bubble formation is due to the water evaporation. Have you tried to use a high solid PVAc? We warm up the glass windows (as carrier) before we apply the film, then the evaporation is more equal. In case you need a sample of a high solid PVAc (approx 60 %) just contact me via: [email protected].
In case you neiter want to heat the adhesive nor use a high solid adhesive as recommended by my friend Dirk Grundwald (hi Dirk): We thoroughly rubbed a spatula over the adhesive which was placed on glass. This eliminated all visible bubbles. Nevertheless, it seems to be impossible to eliminate very small bubbles (see article from Poivet et al.)
Poivet, S., Nallet, F., Gay, C., Teisseire, J. and Fabre, P. (2004). Force response of a viscous liquid in a probe-tack geometry: fingering versus cavitation. The European physical journal. E, Soft matter, 15, 97–116 (2004). doi:10.1140/epje/i2004-10040-2
Hello Hamidreza,
what about adding some amount of solvents in the system, which could lower the boiling temperature of water – earlier removal of excess water from volume, might be it could help to obtain film without the bubbles. At least it works for PF films, when the n-Butanol is added.
BR and good luck
Dirk Grunwald
Hello Dirk,
Thank you for your answer. We could not use high solid content resin because we have to mix it with nano-cellulose in a homogenizer(high rpm) but we will try to warm the substrate before applying the resin.
Dirk Lukowsky
Hi Dirk,
Thanks for the reply, yes it works but takes a long time to eliminate all visible bubbles from each film mechanically. We are looking for a fast method.
Vladimirs Biziks
Hello Vladimirs
Thank you for your answer. We will try it. If it does not change the composition of resin or does not cause an interaction, it is good.
I will inform you (all) If take new results.
Best Regards
Labriit Janka,
parasti maisot - viela tiek uzputota , SpeedMixer - iespeejams straadaa.??? Mana Doma bija , lai speeleejas ar skiidinaataajiem...paaugstinot vai pazeminot uudens izvaikoshanas temp. Drosh ka shajaa gadiijumaa vajadzeetu paaugstinaat uudens virshans temp., lai polimeers saak kondenseeties, bet uudens paarvietojas zu virsmas. kaut kaa taa
Tas drusku savādāks maisītājs.
The SpeedMixer DAC 150.1 FVZ-K works by spinning a high speed-mixing arm in one direction while the basket rotates in the opposite direction (thus, the name - Dual Asymmetric Centrifuge). This combination of forces in different planes enables incredibly fast mixing, and yet the precision construction of each machine gives it a balance that allows amazingly quiet operation.
Ar tādu SpeedMixer Miķelis dabūja savus cietos polimērus bez burbuļiem.
You can minimize size of bubbles if you put PVAC into to vacuum chamber. Let it bubble out, open and see the result.
Hello every one,
We finally found that the best way for elimination of bubbles is using anti-foam agents. Using very low content of it could not affect on strength and adhesion.
Best regards
Hi Hamidreza,
great the you found the way how to eliminate the bubbles in PVAc, you are correct, to avoid the foramation of bubbles (many bubbles - foam) or foaming you can use the anti-foaming agent.
I wish you many, many sucess and get fun from what you are doing.
BR
Vladimirs
Vladimirs Biziks
Dear Vladimirs,
Thank you very much and Good luck!
Hamidreza
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