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Unformatted text preview: travel through it, thus high viscosity, and vice versa. PVA contains a large number of OH groups, one for every two carbon atoms in the polymer chain which makes PVA soluble in water. PVA did not change the viscosity of the solution. PVA can also form hydrogen bonds with borate ions to form cross link between strands of the polymer, producing a mixture consisting of a three-dimensional network of polymer strands that are hydrogen bonded to borate ion and entrapped water molecules. This cross-linking polymer caused the solution to change into a gel substance with really high viscosity. Sulfuric acid reacts with borate ion to break up the cross-links which reverts the solution back into a non-vicious material with a viscosity similar to PVA. Lastly, NaOH neutralized the acid, restoring the cross-linking and gel substance with really high viscosity. Cross- linking significantly increases viscosity....
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