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| OtherNames = PVOH; Poly(Ethenol), Ethenol, homopolymer; PVA; Polyviol; Vinol; Alvyl; Alkotex; Covol; Gelvatol; Lemol; Mowiol |
| OtherNames = PVOH; Poly(Ethenol), Ethenol, homopolymer; PVA; Polyviol; Vinol; Alvyl; Alkotex; Covol; Gelvatol; Lemol; Mowiol; Kuraray Poval, Mowiflex, Alcotex, Elvanol, Gelvatol, Gohsenol, Lemol, Mowiol, Nelfilcon A, Polyviol und Rhodoviol |
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'''Polyvinyl alcohol''' ('''PVOH''', '''PVA''', or '''PVAl''') is a [[water]]-[[soluble]] [[synthetic polymer]] (not to be confused with [[polyvinyl acetate]], a popular wood glue). |
'''Polyvinyl alcohol''' ('''PVOH''', '''PVA''', or '''PVAl''') is a [[water]]-[[soluble]] [[synthetic polymer]] (not to be confused with [[polyvinyl acetate]], a popular wood glue). It has the idealized formula (CH<sub>2</sub>CH(OH)<sub>n</sub>. It is used in papermaking, textiles, and various coatings. It is white (colourless) and is sometimes supplied as beads or as solutions in water.<ref name=Ullmann/> |
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Unlike many [[vinyl]] polymers, PVA is not prepared by polymerization of the corresponding [[monomer]]. The monomer, [[ethenol|vinyl alcohol]] unstable with respect to [[acetaldehyde]]. PVA instead is prepared by first polymerizing [[vinyl acetate]], and the resulting polyvinylacetate is converted to the PVA.<ref name=Ullmann>Manfred L. Hallensleben "Polyvinyl Compounds, Others" in Ullmann's Encyclopedia of Industrial Chemistry, 2000, Wiley-VCH, Weinheim. {{DOI|10.1002/14356007.a21_743}}</ref> Other precursor polymers are sometimes used, with formate, chloroacetate groups instead of acetate. The conversion of the polyesters is usually conducted by base-catalysed transesterification with ethanol: |
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:(CH<sub>2</sub>CH(OAc)<sub>n</sub> + C<sub>2</sub>H<sub>5</sub>OH → (CH<sub>2</sub>CH(OH)<sub>n</sub> + C<sub>2</sub>H<sub>5</sub>OAc |
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⚫ | The properties of the polymer depend on the amount of residual ester groups. Worldwide consumption of polyvinyl alcohol was over one million metric tons in 2006.<ref name="sriconsulting.com"/> Larger producers include [[Kuraray]] (Japan and Europe) and Sekisui Specialty Chemicals (USA) but mainland China has installed a number of very large production facilities in the past decade and currently accounts for 45% of world capacity. |
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==Properties== |
==Properties== |
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Polyvinyl alcohol has excellent film forming, [[emulsion|emulsifying]] and [[adhesion|adhesive]] properties. It is also resistant to oil, grease and [[solvent]]s. It is odorless and nontoxic. It has high tensile strength and flexibility, as well as high oxygen and aroma barrier properties. However these properties are dependent on [[humidity]], in other words, with higher humidity more water is absorbed. The water, which acts as a plasticiser, will then reduce its tensile strength, but increase its elongation and tear strength. |
Polyvinyl alcohol has excellent film forming, [[emulsion|emulsifying]] and [[adhesion|adhesive]] properties. It is also resistant to oil, grease and [[solvent]]s. It is odorless and nontoxic. It has high tensile strength and flexibility, as well as high oxygen and aroma barrier properties. However these properties are dependent on [[humidity]], in other words, with higher humidity more water is absorbed. The water, which acts as a plasticiser, will then reduce its tensile strength, but increase its elongation and tear strength. |
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PVA is fully degradable and dissolves quickly. PVA has a melting point of 230°C and 180–190°C (356-374 degrees Fahrenheit) for the fully hydrolysed and partially hydrolysed grades, respectively. It decomposes rapidly above 200°C as it can undergo [[pyrolysis]] at high temperatures. |
PVA is fully degradable and dissolves quickly. PVA has a melting point of 230 °C and 180–190°C (356-374 degrees Fahrenheit) for the fully hydrolysed and partially hydrolysed grades, respectively. It decomposes rapidly above 200 °C as it can undergo [[pyrolysis]] at high temperatures. |
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PVA is an [[atactic]] material but exhibits [[crystal]]linity |
PVA is an [[atactic]] material but exhibits [[crystal]]linity. |
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PVA is close to incompressible. The [[Poisson's ratio]] |
PVA is close to incompressible. The [[Poisson's ratio]] is between 0.42 and 0.48.<ref name="Fromageau">[http://www.creatis.insa-lyon.fr/~phild/publis/From03IEEE_UFFC.pdf Characterization of PVA cryogel for intravascular ultrasound elasticity imaging], Fromageau, J.; Brusseau, E.; Vray, D.; Gimenez, G.; Delachartre, P.; IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, Volume: 50, Issue: 10. 2003, Page(s): 1318 - 1324.</ref> |
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==Uses== |
==Uses== |
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{{Cleanup|section|date=November 2010}} |
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Polyvinyl alcohol is the raw material to make other polymers like: |
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* Polyvinyl [[acetal]]s: Polyvinyl acetals are prepared by reacting [[aldehyde]]s with polyvinyl alcohol. [[Polyvinyl butyral]] (PVB) and polyvinyl formal (PVF) are examples of this family of polymers. They are prepared from polyvinyl alcohol by reaction with [[butyraldehyde]] and [[formaldehyde]], respectively. Preparation of polyvinyl butyral is the largest use for polyvinyl alcohol in the U.S. and Western Europe. |
* Polyvinyl [[acetal]]s: Polyvinyl acetals are prepared by reacting [[aldehyde]]s with polyvinyl alcohol. [[Polyvinyl butyral]] (PVB) and polyvinyl formal (PVF) are examples of this family of polymers. They are prepared from polyvinyl alcohol by reaction with [[butyraldehyde]] and [[formaldehyde]], respectively. Preparation of polyvinyl butyral is the largest use for polyvinyl alcohol in the U.S. and Western Europe. |
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# [[Carbon dioxide]] barrier in [[polyethylene terephthalate]] (PET) bottles |
# [[Carbon dioxide]] barrier in [[polyethylene terephthalate]] (PET) bottles |
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# As a film used in the [[Hydrographics (printing)|water transfer printing]] process |
# As a film used in the [[Hydrographics (printing)|water transfer printing]] process |
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# As a [[ |
# As a [[form release]] because materials such as [[epoxy]] do not stick to it |
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# Movie [[practical effect]] and children's play [[putty]] or slime when combined with [[borax]] |
# Movie [[practical effect]] and children's play [[putty]] or slime when combined with [[borax]] |
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# Used in eye drops and hard [[contact lens]] solution as a lubricant |
# Used in eye drops and hard [[contact lens]] solution as a lubricant |
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# PVA fiber, as reinforcement in concrete |
# PVA fiber, as reinforcement in concrete |
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# As a surfactant for the formation of polymer encapsulated nanobeads |
# As a surfactant for the formation of polymer encapsulated nanobeads |
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# Used in protective chemical-resistant gloves |
# Used in protective chemical-resistant gloves |
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# [[Imaging phantom|Carotid phantoms]] for use as synthetic vessels in [[Doppler echocardiography|Doppler]] flow testing |
# [[Imaging phantom|Carotid phantoms]] for use as synthetic vessels in [[Doppler echocardiography|Doppler]] flow testing |
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# As agent in artificial Tears for treatment of dry eye. |
# As agent in artificial Tears for treatment of dry eye. |
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Trade names for Polyvinyl alcohol: Kuraray Poval, Mowiflex, Alcotex, Elvanol, Gelvatol, Gohsenol, Lemol, Mowiol, Nelfilcon A, Polyviol und Rhodoviol. |
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The [[North Korea]]n-manufacture fiber [[Vinalon]] is produced from polyvinyl alcohol. Despite its inferior properties as a clothing fiber, it is produced for self-sufficiency reasons, because no [[Petroleum|oil]] is required to produce it. |
The [[North Korea]]n-manufacture fiber [[Vinalon]] is produced from polyvinyl alcohol. Despite its inferior properties as a clothing fiber, it is produced for self-sufficiency reasons, because no [[Petroleum|oil]] is required to produce it. |
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[[Angling|Angler]]s 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. |
[[Angling|Angler]]s 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. |
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==Production== |
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Unlike many [[vinyl]] polymers, PVA is not prepared by polymerization of the corresponding [[monomer]]. The monomer, [[ethenol|vinyl alcohol]], almost exclusively exists as the [[tautomer]]ic form, [[acetaldehyde]]. PVA instead is prepared by partial or complete [[hydrolysis]] (sometimes referred to in this case as [[saponification]]) of [[polyvinyl acetate]] to remove [[acetate]] groups. |
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==See also== |
==See also== |
Revision as of 13:39, 7 September 2013
Names | |
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Other names
PVOH; Poly(Ethenol), Ethenol, homopolymer; PVA; Polyviol; Vinol; Alvyl; Alkotex; Covol; Gelvatol; Lemol; Mowiol; Kuraray Poval, Mowiflex, Alcotex, Elvanol, Gelvatol, Gohsenol, Lemol, Mowiol, Nelfilcon A, Polyviol und Rhodoviol
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Identifiers | |
ChEMBL | |
ChemSpider | |
ECHA InfoCard | 100.121.648 |
E number | E1203 (additional chemicals) |
KEGG | |
RTECS number |
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CompTox Dashboard (EPA)
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Properties | |
(C2H4O)x | |
Density | 1.19-1.31 g/cm³ |
Melting point | 200°C |
Boiling point | 228°C |
Hazards | |
NFPA 704 (fire diamond) | |
Flash point | 79.44°C |
Lethal dose or concentration (LD, LC): | |
LD50 (median dose)
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14,700 mg/kg (Mouse) |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Polyvinyl alcohol (PVOH, PVA, or PVAl) is a water-soluble synthetic polymer (not to be confused with polyvinyl acetate, a popular wood glue). It has the idealized formula (CH2CH(OH)n. It is used in papermaking, textiles, and various coatings. It is white (colourless) and is sometimes supplied as beads or as solutions in water.[1]
Preparation
Unlike many vinyl polymers, PVA is not prepared by polymerization of the corresponding monomer. The monomer, vinyl alcohol unstable with respect to acetaldehyde. PVA instead is prepared by first polymerizing vinyl acetate, and the resulting polyvinylacetate is converted to the PVA.[1] Other precursor polymers are sometimes used, with formate, chloroacetate groups instead of acetate. The conversion of the polyesters is usually conducted by base-catalysed transesterification with ethanol:
- (CH2CH(OAc)n + C2H5OH → (CH2CH(OH)n + C2H5OAc
The properties of the polymer depend on the amount of residual ester groups. Worldwide consumption of polyvinyl alcohol was over one million metric tons in 2006.[2] Larger producers include Kuraray (Japan and Europe) and Sekisui Specialty Chemicals (USA) but mainland China has installed a number of very large production facilities in the past decade and currently accounts for 45% of world capacity.
Properties
Polyvinyl alcohol has excellent film forming, emulsifying and adhesive properties. It is also resistant to oil, grease and solvents. It is odorless and nontoxic. It has high tensile strength and flexibility, as well as high oxygen and aroma barrier properties. However these properties are dependent on humidity, in other words, with higher humidity more water is absorbed. The water, which acts as a plasticiser, will then reduce its tensile strength, but increase its elongation and tear strength. PVA is fully degradable and dissolves quickly. PVA has a melting point of 230 °C and 180–190°C (356-374 degrees Fahrenheit) for the fully hydrolysed and partially hydrolysed grades, respectively. It decomposes rapidly above 200 °C as it can undergo pyrolysis at high temperatures.
PVA is an atactic material but exhibits crystallinity.
PVA is close to incompressible. The Poisson's ratio is between 0.42 and 0.48.[3]
Uses
- Polyvinyl acetals: Polyvinyl acetals are prepared by reacting aldehydes with polyvinyl alcohol. Polyvinyl butyral (PVB) and polyvinyl formal (PVF) are examples of this family of polymers. They are prepared from polyvinyl alcohol by reaction with butyraldehyde and formaldehyde, respectively. Preparation of polyvinyl butyral is the largest use for polyvinyl alcohol in the U.S. and Western Europe.
Polyvinyl alcohol is used as an emulsion polymerization aid, as protective colloid, to make polyvinyl acetate dispersions. This is the largest market application in China.
In Japan its major use is vinylon fiber production.[2]
Some other uses of polyvinyl alcohol include:
- Paper adhesive with boric acid in spiral tube winding and solid board production
- Thickener, modifier, in polyvinyl acetate glues
- Textile sizing agent
- Paper coatings, release liner,
- As a water-soluble film useful for packaging. An example is the envelope containing laundry detergent in "liqui-tabs".
- Feminine hygiene and adult incontinence products as a biodegradable plastic backing sheet.
- Carbon dioxide barrier in polyethylene terephthalate (PET) bottles
- As a film used in the water transfer printing process
- As a form release because materials such as epoxy do not stick to it
- Movie practical effect and children's play putty or slime when combined with borax
- Used in eye drops and hard contact lens solution as a lubricant
- PVA fiber, as reinforcement in concrete
- Raw material to make Polyvinyl nitrate (PVN). an ester of nitric acid and polyvinyl alcohol.
- As a surfactant for the formation of polymer encapsulated nanobeads
- Used in protective chemical-resistant gloves
- Used as a fixative for specimen collection, especially stool samples
- When doped with iodine, PVA can be used to polarize light
- As an embolization agent in medical procedures
- Carotid phantoms for use as synthetic vessels in Doppler flow testing
- As agent in artificial Tears for treatment of dry eye.
The North Korean-manufacture fiber Vinalon is produced from polyvinyl alcohol. Despite its inferior properties as a clothing fiber, it is produced for self-sufficiency reasons, because no oil is required to produce it.
Fishing
PVA is widely used in freshwater sport fishing. Small bags made from PVA are filled with dry or oil based bait and attached to the hook, or the baited hook is placed inside the bag and cast into the water. When the bag lands on the lake or river bottom it breaks down, leaving the hook bait surrounded by ground bait, pellets etc. This method helps attract fish to the hook bait.
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.
See also
References
- ^ a b Manfred L. Hallensleben "Polyvinyl Compounds, Others" in Ullmann's Encyclopedia of Industrial Chemistry, 2000, Wiley-VCH, Weinheim. doi:10.1002/14356007.a21_743
- ^ a b SRI Consulting CEH Report Polyvinyl Alcohol, published March 2007, abstract retrieved July 30, 2008.
- ^ Characterization of PVA cryogel for intravascular ultrasound elasticity imaging, Fromageau, J.; Brusseau, E.; Vray, D.; Gimenez, G.; Delachartre, P.; IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, Volume: 50, Issue: 10. 2003, Page(s): 1318 - 1324.