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Wednesday, March 9, 2011

Polymer Lab Group Investigation

Polyvinyl Lab Group Investigation: Polyvinyl Acetate and Borax Investigation

After the first polymer lab, my group was inspired to further investigate the properties of borax for our next investigation. We wanted to know if borax was truly responsible for the flexibility and rebound of the polymer. In this investigation, we completed three trials: Trial 1 would be the control (nothing would change), Trial 2 would be our variable (35 mL of borax solution), and Trial 3 would be another variable (15mL of solution). The control is used to compare the other Trials with. Trial 2 will allow us to see if more borax solution will allow more “cross-linking” thus leading to tighter bonds and more flexibility/higher rebound. By completing Trial 3, we can back up our theory of Trial 2, because if our theory is correct, then the polymer in Trial 3 will not have much flexibility or very high rebounds. Our hypothesis was If the polymer is most flexible and achieves the highest rebound tests in Trial 2 (the trial using more borax solution), then the borax is responsible because more borax solution was used in it, thus proving that more borax=more flexibility. If our hypothesis was correct, the results should have shown the polymer in Trial 3 to be less flexible or have not very high rebounds. Also, Trial 2 should have shown to be very flexible and fairly high rebounds (in comparison to Trial 1).

As it turned out, Trial 2 did have the highest average (14 cm) for the rebound tests, Trial 3 had the shortest (5.3), and Trial 1 was right in between (10.3). Trial 3 was incredibly mushy, wet, and sticky. It was so wet and sticky that it did not really bounce at all when dropped, and it was very difficult to drop due to it sticking to our hands. Below is a picture of what the Trial 3 Polymer looked like:

Here is what all three Trials looked like side by side:
Trial 1 was soft and moldable. Trial 2 was very firm, it was also stickier than Trial 1, but not squishier. It was also a lot denser. Trial 3 was watery and loose and shapeless. Something that I noticed was that after the removal of Trial 1 polymer, there was a little bit of water and some glue bits left over in the beaker. After the removal of Trial 2, there was at least 30mL of water in the beaker along with glue bits. After the removal of Trial 3, there was no water left, but there was some glue left. I think this is partially because we may have taken out Trial 2's polymer too early, and we may have taken out Trial 3's polymer too late. Thus the polymer soaked up all the water which may have resulted in it's watery-ness.

Then there were the flexibility tests. Below is the chart containing information for all of the tests.

To sum up all the information, at 54 cm, Trial 3 had the most flexibility, at 37 cm, Trial 1 had the second most, and at 26 cm, Trial 2 had the least. There are many explanations for this, but I think that perhaps our information is not completely correct. For one thing, different group members stretched the polymers, which would mean some of them may have been stretched harder and faster or slower. This could speed up the breaking of the polymer, or slow it down. Another thing is that with Trial 3, as mentioned previously, it had been left in the beaker the longest, resulting in it sucking up all the water and being very flexible. Although, Trial 2 was definitely not very flexible, despite the variables. It snapped easily, and was not all that flexible.

In conclusion, our hypothesis was partially correct because Trial 2's results did show that more borax provides more rebound, but it does not necessarily provide more flexibility.





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