Talk:Polyvinyl alcohol

Other uses

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

No, PVA adhesive is normally [[Polyvinyl acetate]]. Lkingscott (talk) 11:01, 11 September 2023 (UTC)

PVA is also used as a spray on mould 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 moulds 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 colourless. 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)

The line about the use in 3d-printing raises questions. Undoubtedly it is used as support material (see all the filament shops selling it for this express purpose). But it is not obvious from the way this sentence is formulated in what way this support works. PVA only solubizes slowly in water and has a lower softening point than a lot of other 3d-printing filaments. Also the note about lost wax casting at the end is not helpful, because it gives the impression that there is a casting process (which there is not when using it as a support in 3d-printing). Hakunamenta (talk) 09:27, 9 April 2019 (UTC)

I assume that the mention of the 3rd print is erroneous. Here, confusion with another substance, Polyvinylpyrrolidone (PVP), which is really used as an adhesive in 3D printing, is possible. — Preceding unsigned comment added by 93.73.222.36 (talk) 12:11, 30 November 2021 (UTC)

Fishing

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

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

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?

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)

Jargon, stilted language, not described....

The overall problem is that the article seems to make no attempt to describe this stuff to the typical reader, as per Wiki guidelines. Readers may feel insulted and ignored.

"Sea of Blue" overlinking such as "water."
Lazy linking such as "cire perdue" used rather than "lost wax casting." Lazy linking is easy, bad writing, and counter-productive to communication. People hate link rabbit holes. Stilted language is self-descriptive.

Jargon, such as: practical effect, polyvinyl acetate dispersions, modifier, PVA fiber, colloid, tautomer. Polite people and good writers never use jargon in mixed company. Links are compromise at best, an invitation to the Back Button.

Assumption of pre-knowledge, —such as this mystery statement: "Anglers also use string made of PVA for the purpose of making temporary attachments. For example, holding a length of line in a coil, that might otherwise tangle while the cast is made," Cool! What special property makes it useful for that? Please describe it (and other cool, related stuff).

The section "Structure and properties" is mis-named, since it only talks about chemical Structure and properties....a general fault of the whole article (double meaning intended). Wikipedia articles should first appeal to the general reader, not ignore her. Describe some commonly known products, if any, for example. Is it rubbery, brittle, does it burn....? It's used to make clothing, yet it's water soluble ...explain. (A list of facts is not an explanation nor a definition, and may be a poor description. ...it's like learning about a topic by studying a test/answer sheet.)

Also, "PVA." Poly(vinyl acetate) PVA, Vs. Polyvinyl alcohol?     Such as: "polyvinylacetate is converted to the PVA." Confusing.

See also: MOS:LEDE ..

The lead should be able to stand alone as a concise overview of the article. It should define the topic, establish context, explain why the subject is interesting or notable, and summarize the most important points—including any prominent controversies. The emphasis given to material in the lead should roughly reflect its importance to the topic, according to reliable, published sources, and the notability of the article's subject should usually be established in the first few sentences....

While consideration should be given to creating interest in reading more of the article, the lead should nevertheless not "tease" the reader by hinting at—but not explaining—important facts that will appear later in the article. The lead should contain no more than four paragraphs, must be carefully sourced as appropriate, and should be written in a clear, accessible style with a neutral point of view to invite a reading of the full article.

--2602:306:CFCE:1EE0:A1F4:1777:6939:15F3 (talk) 18:47, 19 October 2019 (UTC)Communication Effort

Laundry pods

Shouldn’t there be a discussion of laundry detergent pods here? They’re made from PVA and they have possible environmental issues. Roricka (talk) 13:36, 16 July 2022 (UTC)

PVA glue?

Under the "Uses" section there's a sentence talking about PVA glue however as far as I've ever come across (including a quick tertiary Google just now) PVA glues use of "PVA" are referencing polyvinyl acetate not polyvinyl alcohol. This isn't to say there's not some sort of temporary glue meant for breaking down in water that is polyvinyl alcohol based. I'm just not aware of it and I have a feeling that whoever wrote that was getting the two confused. AndrewS ATL (talk) 19:32, 26 June 2023 (UTC)

I removed the sentence about glue and added another describing the ambiguous use of the term PVA for both polyvinyl acetate and polyvinyl alcohol. I believe that the scientific community generally use PVOH rather than PVA, as PVA is normally used for Polyvinyl Acetate. Lkingscott (talk) 11:14, 11 September 2023 (UTC)