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Reliability
A possible source of error could have
stemmed from our film-casting methodology. Originally, we attempted to
melt PVC by heating and mixing in varying amounts of plasticizer. This
method, however, did not work as we were unable to melt PVC into a
fluid without burning it. Seeing as this method did not seem to work,
we decided to dissolve PVC in an accepted solvent, dichloromethane.
This method, however, may have led to a few sources of error. Firstly,
though dichloromethane is listed and accepted as a PVC solvent, it
seemed as if the PVC was not completely soluble, for some PVC particles
clung to the sides of the vial. Despite this, if the same amount of PVC
stuck to each vial, this should not have drastically affected plastic
performance results. Aside from this, we are not entirely sure if all
the dichloromethane evaporated off the film. If not, this could’ve
affected plastic properties. Again though, if the same amount of
solvent was left in each film this should not have affected the
comparison of plastic performance.
Overall, we feel that it is quite safe to say that our testing methods
produced fairly reliable results. We used a spectrophotometer to test
clarity, and with the use of this technology were able to obtain very
precise results that would’ve been impossible to detect with the naked
human eye. To account for the fact that there may have been a
discrepancy in terms of clarity across the film, we took five readings
from each film. Considering that the films were one-inch squared, the
average of five readings would have produced fairly reliable results.
While the compression test may seem somewhat crude and open to human
error, the test was performed on three areas of each film, and the
percent compression was very reproducible.
The flexibility test results were likely quite reliable, as a Zeta
Meter machine was used to read the very small increments of deflection
that would’ve been impossible to detect with the naked human eye.
Despite this, there would’ve been slight room for error in that it was
important that each film was clamped at precisely 1cm, and that the
weight was placed at the exact same position.
Project
Conclusion
From our results, it seems as if
safflower oil would be the best potential commercial PVC primary
plasticizer. In the elastic modulus graph, its line very closely
mirrors that of the currently commercially used DEHP. These results are
very encouraging, as safflower oil is safe in terms of production, use,
and disposal, and is also cheap and accessible. While safflower oil was
definitely the best performer of the plasticizers alternatives tested
in this experiment, we must caution not to completely disregard the
other plasticizers tested. Sunflower oil, for instance, also showed a
significant amount of promise as a potential PVC primary plasticizers.
The plasticizers that showed properties that differed from this gained
from the use of PVC, could be used in products where these properties,
such as flexibility or elasticity need not be so great.
Future Study
A possible future take to this
study could be to mix the vegetable oils tested in this experiment with
DEHP to enhance the vegetable oils’ plasticizing effect while
minimizing DEHP’s detrimental effects. Aside from this, other vegetable
oils could be tested. Our results indicated that the more poly
unsaturated fatty acids in the oil, the better performance would be.
Future studies could delve into this area of study.
Seeing as DEHP works well as a plasticizer but is toxic, a future study
could delve into finding a possible coating for DEHP to prevent
leaching. This would not solve its non-biodegradable problems, but this
would at least make the PVC plastics safer in terms of production, use
and disposal.
Another possible area of study, would be to examine whether sunflower
oil could be used as a possible alternative for plasticizers other than
DEHP. Our particular experiment was very limited in scope, in that it
only dealt with PVC plastics, and at that only its primary
plasticizers. It would be interesting to further examine other
plasticizers used in other plastics.
Acknowledgements
We’d like to extend a sincere
thank-you to:
Dr. Helen Burt, Mr. John Jackson, and the UBC Cunningham Building for
covering the costs of materials, and for allowing us to conduct our
experiment in their laboratories.
Dr. Geoffrey Gabbott, our sponsor teacher, for his invaluable support.
Without these people, our project would not have been possible.
References
For references, please
click here.
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