Results and Discussion The purpose of this experiment was to determine the effects of cross-linking on the viscosity of a polymer solution. To measure the viscosity quantitatively, each solution was placed in a 25 ml graduated cylinder. Then, the amount of time a steel ball took to drop to the bottom of the graduated cylinder was timed. The more time it took to reach the bottom of the graduated cylinder, the more viscous the solution was. In addition, observations were made to supplement quantitative measurements with qualitative ones. First, a solution of 2.000 g of the polymer poly(vinyl alcohol) (PVA) was created by slowly sprinkling the PVA into a beaker of water on a hot plate. The solution created was clear. Next, 0.4 g of borax (Na 2 B 4 O 7 * 10H 2 O) and 10 ml of hot water was added into the cooled solution. The reaction between the water and borax follows: Na 2 B 4 O 7 * 10H 2 O (x) 2B(OH) 3(aq) + 2Na + (aq) + 2B(OH) 4-(aq) + 3H 2 O (l) The addition of borate ions cross-linked PVA chains by making hydrogen bonds between strands
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This test prep was uploaded on 02/01/2008 for the course CHEM 342132 taught by Professor Davis during the Spring '08 term at Cornell University (Engineering School).