please tell me every about polyvinyl alcohol the history,...

Answer by aqua
Submitted on 9/27/2006
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Preparation: Unlike most vinyl polymers, PVOH is not prepared by polymerization of the corresponding monomer. The monomer, vinyl alcohol, almost exclusively exists as the tautomeric form, acetaldehyde. PVOH instead is prepared by partial or complete hydrolysis of polyvinyl acetate to remove acetate groups. ----------------------------------- Properties: Polyvinyl alcohol has excellent film forming, emulsifying, and adhesive properties. It is also resistant to oil, grease and solvent. PVOH is an atactic material but exhibits crystallinity as the hydroxyl groups are small enough to fit into the lattice without disrupting it. It has high tensile strength, flexibility, as well as high oxygen and aroma barrier. 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. PVOH has a melting point of 230°C and 180-190°C for the fully hydrolysed and partially hydrolysed grades. PVOH also decomposes rapidly above 200°C ------------------------------------------- USES: Some uses of polyvinyl alcohol include: 1. Adhesive and thickener material in latex paints, paper coatings, hairsprays, shampoos and glues. 2. Carbon dioxide barrier in polyethylene terephthalate (PET) bottles. 3. Carotid phantoms for use as synthetic vessels in doppler flow testing. 4. Children's play putty or slime when combined with Borax. 5. Feminine hygiene and adult incontinence products as a biodegradable plastic backing sheet. 6. As a mold release because materials such as epoxy do not stick to it. 7. As a water-soluable film useful for packaging. 8. As fiber reinforcement in concrete

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Question by hoangminh
Submitted on 12/17/2003
Related FAQ: Sci.chem FAQ - Part 1 of 7
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please tell me every about polyvinyl alcohol the history, producing , .... thank you

Answer by crystynai
Submitted on 3/16/2004
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I need all the informations about polyvinyl alcohol. Thank you.

Answer by Bendhot
Submitted on 3/10/2005
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I need the flow diagram process of the making polyvinyl alcohol from vinyl acetate

Answer by Ekele
Submitted on 4/28/2005
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a polyvinyl alcohol is a polymer used in degrading plastic products.

Answer by Tetê
Submitted on 8/22/2005
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I need all the informations about polyvinyl alcohol. Thank you

Answer by ishaq
Submitted on 10/3/2005
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polyvinyl alcohol resin pva 117 or 217 used in clothes or fiber for strengthness.

Answer by paresh
Submitted on 10/8/2005
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WHICH ARE THE AVAILABLE GRADE FOR THE FULLY HYDROLYSED GRADE WHICH HAD VISCOSITY 5-7.? WE SHALL BE THANKFUL TO YOU FOR YOUR KIND INFORMATION SD- PARESH JASANI

Answer by cha
Submitted on 11/22/2005
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-It is used as a starting material for the preparation of other resins. It can be used as a component of elastomers used in the manufacture of sponges. This polymer is used in sizing agents that confer resistance to oils and greases upon paper and textiles, to make films resistant to attack by solvents or oxygen. It is used as a component of adhesives, emulsifiers, suspending and thickening agents. In pharcuetical industry, Polyvinyl alcohol is used as a ophthalmic lubricant and viscosity increasing agent. It thickens the natural film of tears in eyes.

Answer by freak4science
Submitted on 4/19/2006
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well, polyvinyl alcohal is very simple to understand. it is white, has a mild oder and is moderatley souluble. it is stable under normal circumstances. when solid form, has a melting point of 200* C. when combined with sodium tetroborate, it can be made into slime.

Answer by PHIPHI
Submitted on 4/27/2006
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don't check my spelling you should check yours. sincerly, The teacher's Staff

Answer by yashar
Submitted on 5/17/2006
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I need all the informations about polyvinyl alcohol. Thank you.

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