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Casting Plastic
Films:
1. PVC and plasticizer weight-ratios were combined in separate
sterilized vials, using the table shown below.
|
Plasticizer Concentration |
0% |
10% |
20% |
30% |
40% |
| PVC |
250 mg |
225 mg |
200 mg |
175 mg |
150 mg |
| Plasticizer |
0 mg |
25 mg |
50 mg |
75 mg |
100 mg |
2. 5 mL of dichloromethane solvent was added to each vial.
Sample vials
(click for enlarged)
3. Teflon paper was cut into 2.4 cm by 2.4 cm squares and one
square was placed onto each microscope slide.
Sample slides
(click for enlarged)
4. To cast plastic films, pipettes were used to drop 1 mL of
each solution onto the Teflon paper covered slide. 3 films were cast
for each solution.
5. The slides were heated for fifteen minutes in a 60º oven to
evaporate the dichloromethane solvent.
6. Forceps were used to peel the plastic films off the Teflon
paper.
Pipettes used in the experiment
(click for enlarged)
Testing plastic performance:
1. Transparency
A spectrophotometer was used to record the amount of light absorbed at
the 450nm wavelength. Five readings were taken for each film.
Spectrophotometer
(click for enlarged)
2. Flexibility
The films were then tested for flexibility by clamping each film
between two microscope slides so that 1 cm was left unclamped. Using a
pipette, 0.25 mg of distilled water was dropped 0.5 cm from the edge of
the film, and the amount of deflection was read through a Zeta-Meter
apparatus. A sheet of tin foil was placed behind the film to refract
light, making the readings from the machine clearer. By using the
formula for flexural stress, E (Elastic Modulus) for each sample was
calculated:
Zeta-Meter apparatus
(click for enlarged)
Schematic diagram of Zeta-Meter apparatus
(click for enlarged)
3. Compression
Magnitude
The final plastic performance test conducted was a compression test.
This was done by measuring the thickness of the film with a Mituyoyo
micrometer and then compressing the film by gently turning the knob of
the micrometer with a consistent amount of pressure until the amount of
applied force could compress the plastic no further. At this point, the
new reading was recorded and percent compression calculated by the
formula:
This compression reading was taken from three random points on each
film.
Mituyoyo micrometer
(click for enlarged)
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