User:Moira M. Esson/Notebook/CHEM-581/2012/08/31: Difference between revisions
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== Preparation of PVOH Stock Solutions== | == Preparation of PVOH Stock Solutions== | ||
#In a clean 600mL beaker, place 200mL distilled H<sub>2</sub>O with a magnetic stirrer and heat until ~90°C | #In a clean 600mL beaker, place 200mL distilled H<sub>2</sub>O with a magnetic stirrer and heat until ~90°C | ||
#Slowly add 5grams of PVOH (MW 22,000) over a 30 minute period. Continuously stirring. Stir slowly to avoid frothing of the gel. | #Slowly add 5grams of PVOH (MW 22,000) over a 30 minute period. Continuously stirring. Stir slowly to avoid frothing of the gel. Heat and stir until polymer is completely dissolve | ||
#*'''Note''': The polymer is completely dissolved when the solution is clear(~1hr of heating) | |||
# Let the solution cool to room temperature. | # Let the solution cool to room temperature. | ||
# Pour into a 500 mL volumetric flask and fill with H<sub>2</sub>O. | # Pour into a 500 mL volumetric flask and fill with H<sub>2</sub>O. | ||
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#* Use 1.25 mL of 15.95 mM solution to dilute to 3.99 mM | #* Use 1.25 mL of 15.95 mM solution to dilute to 3.99 mM | ||
#* Use 6.25 mL of 15.95 mM solution to dilute to 1.99 mM | #* Use 6.25 mL of 15.95 mM solution to dilute to 1.99 mM | ||
==Viscosity of PVOH Stock Solutions== | |||
'''General Procedure''': | |||
#Using an Ostwald viscometer, time the rate at which H<sub>2</sub>O flows from the top most line to the bottom most line. Run at least three trials | |||
#*'''Note''':The amount of solution in the viscometer does not matter, but the viscometer can hold no more than 10mL | |||
#Measure the temperature of the surroundings. Record the temperature | |||
#Rinse the same viscometer with the lowest concentrated stock solution that needs to be tested | |||
#Time the rate at which the lowest concentrated stock solution flows from the top most line to the bottom most line. Run at least three trials | |||
#Repeat steps 2 and 3 for each of the stock solutions, ensuring to systematically increase the concentration of each stock solution tested | |||
'''Viscosity Calculations''' | |||
* Viscosity of pure H<sub>2</sub>O at 26°C | |||
{| {{table}} | |||
| align="center" style="background:#f0f0f0;"|'''Trial [ ]''' | |||
| align="center" style="background:#f0f0f0;"|'''Time [s]''' | |||
|- | |||
| 1||238.79 | |||
|- | |||
| 2||242.62 | |||
|- | |||
| 3||241.63 | |||
|- | |||
|} | |||
* Average time = 241.01 s | |||
<br> | |||
* Viscosity of 1.99 mM PVOH in H<sub>2</sub>O at 26°C | |||
{| {{table}} | |||
| align="center" style="background:#f0f0f0;"|'''Trial [ ]''' | |||
| align="center" style="background:#f0f0f0;"|'''Time [s]''' | |||
|- | |||
| 1||279.37 | |||
|- | |||
| 2||281.97 | |||
|- | |||
| 3||283.12 | |||
|- | |||
|} | |||
* Average time = 281.49 s | |||
<br> | |||
* Viscosity of 3.99 mM PVOH in H<sub>2</sub>O at 26°C | |||
{| {{table}} | |||
| align="center" style="background:#f0f0f0;"|'''Trial [ ]''' | |||
| align="center" style="background:#f0f0f0;"|'''Time [s]''' | |||
|- | |||
| 1||246.42 | |||
|- | |||
| 2||250.31 | |||
|- | |||
| 3||251.86 | |||
|- | |||
|} | |||
* Average time = 249.53 s | |||
<br> | |||
* Viscosity of 7.98 mM PVOH in H<sub>2</sub>O at 26°C | |||
{| {{table}} | |||
| align="center" style="background:#f0f0f0;"|'''Trial [ ]''' | |||
| align="center" style="background:#f0f0f0;"|'''Time [s]''' | |||
|- | |||
| 1||273.99 | |||
|- | |||
| 2||276.73 | |||
|- | |||
| 3||278.63 | |||
|- | |||
|} | |||
* Average time = 276.45 s | |||
==Preparation== | |||
*Prepared 500mL stock solution of PVOH (MW 130,000)in H<sub>2</sub>O | |||
==Observations== | |||
*PVOH (MW 130,000) film(prepared 08/29/12) when dried was very rigid and curled slightly | |||
*Preparation of 500mL stock solution of PVOH (MW 130,000)in H<sub>2</sub>O required more time(~2-2.5 hrs). Complete dissolution of the polymer required extra time and more vigorous stirring | |||
**When dissolving the PVOH (MW 130,000) a large gel-like sphere formed in the center of the solution | |||
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Revision as of 18:34, 4 September 2012
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Objectives
PVOH plus acid films
Preparation of PVOH Stock Solutions
Viscosity of PVOH Stock SolutionsGeneral Procedure:
Viscosity Calculations
Preparation
Observations
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