Polymer Cross

Polymer Cross - Polymer Cross-linking and Viscosity Results...

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Polymer Cross-linking and Viscosity 11/14/08
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Results and Discussion Purpose The purpose of this experiment was to test the effects of cross- linking on the viscosity of polymer solutions. Borate ion was first used to cross link the PVA and the viscosity was tested. Then viscosity was tested after the breaking of the cross-linking with sulfuric acid and the reforming of the cross-linking with the addition of sodium hydroxide. Viscosity was tested when possible by recording the time it took for a marble to drop through 25 ml of solution in a graduated cylinder. A solution was first made with PVA and water. The Borate ion was then formed according to: Na 2 B 4 O 4 •10H 2 O → 2B(OH) 3 + 2Na + + 2B(OH) 4 - + 3H 2 O. The borate ion’s tetrahedral shape helped cross-link the PVA and increase viscosity. Sulfuric acid was then used to break down the borate ion and therefore most of the cross-linking according to the equation: 2B(OH) 4 - + H 2 SO 4 2B(OH) 3 + SO 4 2 - + 2H 2 O. Finally, the cross-
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This note was uploaded on 11/06/2010 for the course CHEM 2070 at Cornell.

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Polymer Cross - Polymer Cross-linking and Viscosity Results...

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