poly (vinyl butyral) film

Hi, this is not my area of expertise but I am currently working with PVB (7.5g Pioloform BM18, dissolved in 100mls 1-butanol, 24hrs @ 50
degrees C) . I make up various concentrations of chloral hydrate in thymol blue dye. Then add 3mls of this solution to around 20mls PVB mixture. The problem is that I don't understand the interactions between these compounds and how well they mix together. After mixing for a few hours they are poured on 15cm x 15cm horizontal glass plates. Upon drying over 2 days there is a wave effect noticable on the surface and not smooth as I would like. I also think the chloral hydrate/ dye is not properly dispersed throughout the film once dried. Any info on how these compounds may intereact and how I can produce a smooth thin layer film with dye and chloral hydrate dispersed throughout PVB matrix would be appreciated.
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If you are not aware of this article: Journal of Photochemistry and Photobiology A: Chemistry Volume 137, Issue 1 , 24 October 2000, Pages 37-43 Thymol-blue dyed poly(vinyl butyral) films for monitoring ultraviolet radiation
John Aspen Research, - www.aspenresearch.com "Turning Questions into Answers"
Opinions expressed herein are my own and may not represent those of my employer.
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Have you made a smooth film from PVB solution, using the same conditions and no chloral hydrate/thymol blue?
PVB is made by reacting the OH groups of polyvinyl alcohol with butyraldehyde, but a significant fraction of the OH groups are left un-reacted. Under acidic conditions, chloral is likely to react with some of the OH groups.
Thymol blue should have some solubility in 1-butanol. Is the chloral needed for a specific purpose or is just a solvent?
Ernie
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Hi Ernie and John, thanks for the info, much appreciated. I am using the protocol in the PVB paper John mentioned but there is no mention of this wave effect or much info on the drying of the film. I have set up a film with no Chloral hydrate as a control but not a PVB film only. I may try this to see what the film dries like. From my work varying Thymol blue(TB):chloral hydrate (CH) ratios I've noticed that increasing CH concentration makes the film more sticky upon drying and makes it difficult to peel. Increasing TB has the opposite effect. The specific purpose of CH is that it is responsible for colour change in the TB containing films. I'll set up films without TB or CH to see if wave effect is present but I think it will be there in a TB/PVB film with no CH.
Many thanks for your help,
Aoife.
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Hi, I set up a PVB film (no CH or TB) and same conditions but there was very noticable wave effect on the film surface. I poured it and left it to dry in the fume hood (which was switched on) as the drying film stinks. I think the air flow over the film might be causing this wave effect and not the TB or CH. I think I need to find a way to set up the film where air flow is not a problem and people won't complain of the stink! Any suggestions on what's the best way to dry the film in order to get a smooth surface?
Thanks, Aoife.
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