User:Moira M. Esson/Notebook/CHEM-581/2012/09/07

Objectives

• Crosslink PVOH films through dehydration.
• Prepare more PVOH (MW 130,000) films using HCl, H_{3<sub/>PO4,and maleic or succinnic acid}
• Run solubility tests of crosslinked and uncrosslinked PVOH films
• Run Fourier Transform Infrared Spectroscopy (FTIR) and Differential Scanning calorimetry(DSC) on PVOH films

PVOH(MW 130,000) Films

• The standard protocol for PVOH Film preparation was used.
  • Note: If indicated that acid was added

Prepared PVOH(MW 130,000) Films

Note:Complete dissolution of the PVOH required a longer amount of stirring(~2hours) and the addition of more deionized H_{2<sub/>O. To prompt complete dissolution, solutions were transferred to larger beakers(~50mL) with larger amounts of H2<sub/>O.}

Crosslinking PVOH Films

Standard Protocol for Crosslinking of films:

1. Weigh out ~0.2 grams of film
2. Place measured film in round metal tray
3. Place tray in oven at ~120 degrees C for 90 minutes

Crosslinked PVOH Films:

1. PVOH(MW 22,000) with 15 wt% maleic acid
2. PVOH (MW 22,000) with 15 wt% succinic acid

Solubility of PVOH Films

General Protocol:

1. Place ~0.1g of film to be tested in a 100mL beaker.
2. Add a stir bar to the beaker
3. Place plastic stemless buchner funnel top above the film and stir bar
4. Using a plastic pipette(s) to hold down the plastic mesh, add ~75mL of deionized H_{2<sub/>O to the beaker.}
5. Allow the film to completely dissolve

• • Gently stir the solution only with the stir plate. DO NOT add heat

1. Once the film is completely dissolved, test the viscosity of the solution three times

Viscosity of uncrosslinked PVOH(MW 22,000) 15wt% maleic acid

• Average time:250.28 s

DSC on PVOH Films

DSC will be used to determine the different thermal transitions of the various films General Protocol for DSC:

1. Weigh out the mass of a Tzero pan+Tzero lid(Record this measurement)
2. Cut and weigh out ~ 280 - 320mg of PVOH film sample to place in the Tzezo pan
3. Once each sample is placed in the pan, then place the lid onto the pan
4. Use a Tzero press to secure and press the lid tightly over top the sample within the pan
5. Open TA instrument explorer on computer. Select instrument to be used(in this case DSC)
6. On control button, click event to create a new event
7. To create a new event or run, click either the apply or append commands
8. To modify a run, go to the experimental command and run a method edit
9. Save all changes made to an experimental run in order to analyze samples

To Collect the information from the DSC:

1. Click on export data file command
2. Go to file and plot signals command
3. Export the information obtained and save it(if possible save on flash drive)
4. Go to signals command and select signal section, then time command underneath
5. Select the analyze data command, then afterwards the integrate peaks command underneath
6. Accept values established by integrating the peaks
7. Click the analyze data command again to assign the glass transition value
8. Select the area in which the glass transition point is seen and integrate that information
9. Accept the values established from the glass transition point

• About 3 mg ± 20% PVOH film was placed in a DSC pan.
• Uncrosslinked PVOH (MW 22000) + 15% maleic acid + H₃PO₄
  • Pan mass: 49.42 mg
  • Sample mass: 3.13 mg

• Uncrosslinked PVOH (MW 22000) + 15% succinic acid + H₃PO₄
  • Pan mass: 51.02 g
  • Sample mass: 3.15 g
• Graph of heat flow of uncrosslinked PVOH (MW 22000) + 15% maleic acid + H₃PO₄.
  • Two possible glass transitions at 105.79°C and at 155.16°C were observed(able to observe on graph by looking at the change in slope). Running DSC on the sample a second time may clarify which is the true glass transition temperature.
  • Two sharp peaks at 144.66°C and at 155.64°C were observed. A reaction may have occurred at these temperatures or a phase change may have occurred
• Graph of heat flow of uncrosslinked PVOH (MW 22000) + H₃PO₄.
  • A glass transition was observed at 82.61°C.
  • A sharp peak was observed at 179.47°C. This may be caused by a reaction or phase change.

Notes

1. For Solubility still need to test:

• PVOH (MW 22,000) uncrosslinked with 15wt% succinnic acid
• PVOH (MW 22,000) uncrosslinked with 10wt% maleic acid
• PVOH (MW 22,000) crosslinked with 15wt% maleic acid
• PVOH (MW 22,000) crosslinked with 15wt% succinnic acid
• PVOH (MW 22,000) uncrosslinked with 10wt% succinnic acid
• PVOH (MW 22,000) uncrosslinked
• PVOH (MW 22,000) crosslinked

1. For films need to prepare:

• PVOH (MW 130,000) uncrosslinked with 15wt% maleic acid
• PVOH (MW 130,000) uncrosslinked with 10wt% maleic acid
• PVOH (MW 130,000) crosslinked with 15wt% maleic acid
• PVOH (MW 130,000) crosslinked with 10wt% maleic acid
• PVOH (MW 130,000) uncrosslinked with 15wt% succinic acid
• PVOH (MW 130,000) uncrosslinked with 10wt% succinic acid
• PVOH (MW 130,000) crosslinked with 15wt% succinic acid
• PVOH (MW 130,000) crosslinked with 10wt% succinic acid
• PVOH (MW 130,000) uncrosslinked(and crosslinked) with 15wt% succinic acid and HCl
• PVOH (MW 130,000) uncrosslinked(and crosslinked) with 10wt% succinic acid and H₃PO₄
• PVOH (MW 130,000) uncrosslinked(and crosslinked) with 15wt% maleic acid and HCl
• PVOH (MW 130,000) uncrosslinked and crosslinked with 10wt% maleic acid and H₃PO₄
• PVOH (MW 22,000) uncrosslinked and crosslinked with 10wt% maleic acid
• PVOH (MW 22,000) uncrosslinked and crosslinked with 15wt% maleic acid
• PVOH (MW 22,000) uncrosslinked and crosslinked with 10wt% succinic acid
• PVOH (MW 22,000) uncrosslinked and crosslinked with 15wt% succinic acid
• PVOH (MW 22,000) uncrosslinked and crosslinked with 10wt% maleic acid and H₃PO₄
• PVOH (MW 22,000) uncrosslinked and crosslinked with 15wt% maleic acid and HCl
• PVOH (MW 22,000) uncrosslinked and crosslinked with 10wt% succinic acid and H₃PO₄
• PVOH (MW 22,000) uncrosslinked and crosslinked with 15wt% succinic acid and HCl

Observations

• Crosslinked PVOH films became more rigid and changed color from transparent to faintly yellow-brown.
• The viscometer used for previous tests was discovered to be cracked. A new viscometer was subsequently used.