Talk:Polyvinyl alcohol

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Other uses[edit]

PVA is an adhesive. It is used as postage stamp gum. 87.65.147.110 (talk) 00:15, 16 December 2011 (UTC).

PVA is also used as a spray on mold release in some types of plastics fabrication, especially glass reinforced polyester or epoxy resin. Its water soluble and biodegradeable properties make it easy to completely remove from the molds and fabricated parts simply by washing with water.

PVA is widely used as binder to improved the green strength and pressability in soft ferrite materials. PVA together with plasticizer has an great impact to develop green strength in intricate part made with soft ferrite material.e.g. MnZn Ferrite, NiZn Ferrite

PVA is used in the biomedical research field as a salt bridge (when saturated with a supporting electrolyte) in microscale electrochemical applications. It is also used as a supporting medium for cryomicrotomy sectioning of tissue for histological study.

There are two types of "school glue" sold in retail stores. One type is white (which may be either polyvinyl acetate or a blend of polyvinyl acetate + polyvinyl alcohol). The other type (Example: 3M Scotch 'Clear Glue with 2-Way Applicator') is clear and colorless. Is the clear one an aqueous solution of polyvinyl alcohol? If not, then what is that stuff? I'm curious.--Zymatik 15:33, 25 June 2007 (UTC)

Fishing[edit]

I removed this line from the fishing section:

PVOH is odorless and nontoxic, but can undergo pyrolysis at high temperatures. There are varieties approved by the FDA for direct food contact.

The first part (about odor & toxicity) I put in the Properties section. The second part about the FDA doesn't make sense - what "varieties" are being referred to? This should be corrected/clarified and put back. Dhollm 10:07, 25 April 2007 (UTC)

Flash point[edit]

The flash point should be much higher (at the pyrolysis temerature) or nonexistant. The flash point article mentions only liquids, and I doubt a piece of plastic gives off enough vapors at 80 decrees to be combustible. 217.19.29.156 (talk) 20:18, 31 January 2010 (UTC)

Other uses[edit]

I have recently discovered that this material is being used as a flushable dog poop bag. I am puzzled about its supposed 'degradability', though. In one section of the article it says 'degradable' and in another 'bio-degradable.' These are 2 separate qualities. Can someone clarify? Grandma Roses (talk) 15:00, 17 July 2011 (UTC)

The definition of "degradation" is rather simple: a material is degradable if it goes through a standard sieve after a determined number of years in a landfill. But, PVA is degradable, even though poorly. --vuo (talk) 00:00, 22 September 2012 (UTC)

How realistic is the inclusion of a Melting point and boiling point for PVA?[edit]

How can we define a melting point and boiling point (or decomposition point) for a polymeric material, without specifying molecular weight range? According to Melting point and heat of fusion of poly(vinyl alcohol, by Robert K. Tubbs, (DOI: 10.1002/pol.1965.100031213), Journal of Polymer Science Part A: General Papers, Volume 3, Issue 12, pages 4181–4189, December 1965, this value is 228 C. This is according to the abstract, as I don't have access to the paper itself. According to http://www.fao.org/fileadmin/templates/agns/pdf/jecfa/cta/61/PVA.pdf, the melting point is 180-190 C, but also defines the molecular weight range. MakerBot lists the melting point as 160-170 C (http://wiki.makerbot.com/pva) with no definition of molecular weight range. I think the inclusion of a boiling point and melting point is probably a bad idea without further explanation.JSR (talk) 13:09, 21 September 2012 (UTC). Melting point of PVA varies a lot depending on the level of Hydrolysis.

The value of 228 C will refer to a fully-hydrolysed PVA (near 100% pure PolyVinyl Alcohol). Commercial grades of PVA vary in hydrolysis from near 100% downwards to below 70% in some cases. These grades a technically PVA/PVAc (PolyVinyl Acetate) co-polymers, although they are still sold and referred to as PVA's. As the PVAc content increases the melt temperature decreases. Furthermore the Makerbot types will either be plasticised, reducing melting point further or are more complex co-polymers such as PVA/Ethylene which are usually more thermoplastic and have lower melting points.81.136.250.24 (talk) 15:40, 16 April 2014 (UTC)