Activity 2.6 - Testing the Pore Size of Plasticised and Un-Plasticised PVC

The PVC films from Activity 2.5 (with and without plasticizer, i.e. films with different sized holes) can be used to separate different compounds or the compounds can be used to determine the pore size (i.e. larger or smaller than the molecular size).

• Water
• Iodine Solution
• Potassium Permanganate solution

Devise a suitable procedure using material available and previous experiments.

• Rank each PVC film in terms of permeability, starting from non permeable to permeable.
• WDifferentiate between the structure and size of iodine molecules and potassium permanganate molecules in solution.
• At what point does the plasticiser allow the PVC to become permeable to iodine?
• Explain what happens on a molecular level.
• Why was parafilm used as well as PVC?
• Give examples of other polymers you think may be permeable / impermeable and construct an experiment to test this.