7-Polymer Cross-Linking and Viscosity

7-Polymer Cross-Linking and Viscosity - Results and...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Results and Discussion The purpose of this experiment was to determine the effect of cross-linking on polymer solution viscosity. Borate ion, B(0H) 4 - was used to cross-link strands of poly(vinyl alcohol). 1. Prepare a cross-linked PVA solution. 2 g of PVA were slowly dissolved into water (approximately 90ºC) for 1.5 hours. When it was complete, the solution was clear. The borax was dissolved in water to form a solution. Na 2 B 4 O 7 . H 2 O 2 B(OH) 3 (aq) + 2 Na + (aq) + 2 B(0H) 4 - (aq) + 3 H 2 O(l) The borate ions were able to cross-link the PVA by forming hydrogen bonds. 2. Remove cross-linking by addition sulfuric acid. 2 B(0H) 4 - (aq) + H 2 SO 4 (aq) 2 B(OH) 3 (aq) + SO 2 - (aq) + 2 H 2 O(l) 2. Restore cross-linking by added a base to neutralize the acid. Therefore, cross-linking increased the polymer solution viscosity and there is an observable change. In addition, the removal of the cross-linking by sulfuric acid did not bring about a complete restoration of the pre-cross-linked polymer solution viscosity. The neutralization of the acid led to the restoration of cross-linking and an increase in
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 04/14/2008 for the course CHEM 007 taught by Professor Staff during the Fall '07 term at Cornell.

Page1 / 2

7-Polymer Cross-Linking and Viscosity - Results and...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online