||This article needs additional citations for verification. (August 2007)|
|LD50||14,700 mg/kg (Mouse)|
| (what is: /?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
PropertiesPolyvinyl 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 as the hydroxyl groups are small enough to fit into the lattice without disrupting it.
PVA is close to incompressible. The Poisson's ratio has been measured to between 0.42 and 0.48.
||This section may require cleanup to meet Wikipedia's quality standards. (November 2010)|
- Polyvinyl nitrate (PVN): It is an ester of nitric acid and polyvinyl alcohol.
- 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.
In Japan its major use is vinylon fiber production.
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 mold 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
- 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.
- See more specific polyvinyl alcohol uses
FishingPVA 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.