Wednesday, March 9, 2011

Polymer Lab Group Investigation

The purpose of this lab is to see if the borax is responsible for the flexibility/rebound of the polymer. 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. My hypothesis is that if the polymer is most flexible and bouncy in trial 2, then the borax is responsible for it because trial 2 has more borax solution in it.
Materials used include120mL White Glue Bottle (polyvinyl acetate), 1575mL Water, 1 Stirring Rod, 1 Ruler, 1 500mL Beaker, 1 250mL Beaker, 1 Graduated Cylinder, Box of Borax (hydrated sodium borate), and 1 Teaspoon.
To conduct this experiment is quite simple. First, gather all the materials, and have them at a accessible distance. Then pour 400mL of water into the larger beaker. Whenever pouring liquids into beakers, be sure to have them on a flat surface for accurate results. Now, to make the solution, take the teaspoon and scoop out some of the borax. Take the stirring stick or ruler and use it to level out the powder in the spoon and make it flat. Empty the teaspoon into the large beaker with water. Repeat this step for the second teaspoon. Now stir the borax and water mixture with the stirring stick for about five minutes, or as long as it takes to dissolve the borax into the water. Borax is dissolved when the water in large beaker is clear and not cloudy. If there are any clumps of borax settled at the bottom of the beaker, mix them around with the stirring stick. Now set aside the beaker, it will be used later on. Take the bottle of glue and empty it into the small beaker. Do no use the graduated cylinder because it will be hard to pour glue from. If the glue bottle has a cap, uncap it, and hold the bottle directly above the center of the beaker. Tilt the glue bottle slowly, and pour glue into the center of the beaker so as not to cover the measurements. Make sure you pour 40 mL of glue into each separate large beaker. Once the glue fills up 40mL on the beaker, stop pouring. Now measure out 5mL of water with the graduated cylinder. Pour it into the beaker with glue in order to dilute the glue (the monomer). Slowly stir the glue and water mixture with the stirring stick (be sure to dry it off first). Next, pour 25mL of the borax solution into the glue while simultaneously stirring the glue. In order to add the borax solution into the glue, first pour the 25mL into the graduated cylinder to get an exact amount. Empty this into the first beaker. Next, measure 35 mL of the borax solution in the graduated cylinder, and empty that into the second beaker. Lastly, measure 15 mL of the borax solution in the graduated cylinder, and empty that into the third beaker. Slowly pour the solutions into the beakers, and stir until each beaker contains a solid. Once each container has a solid in it, feel it, observe it, and mess around with each of them. Make sure you remember which one is from each beaker. Now, one at a time, take off a piece of each polymer. Remember to keep them separate from each other so you can keep track of which polymer has more or less borax solution. Roll the broken off piece into a ball. Drop it from a height of 30 cm and record its rebound height. Do this for all the polymers. Then, reattach the ball to the rest of the polymer and form it into an oval shape. Lay the ruler flat on the table, and stretch each polymer starting at the zero mark. Record its flexibility point and breaking point and compare them with each other.

These were our results:
Trial 1 (Control)Trial 2 (More)Trial 3 (Less)
Rebound Test Results10 cm, 6 cm, 15 cm,
Ave: 10.3cm
13, 14, 15
Ave: 14
4, 5, 7
Ave: 5.3
Flexibility Test Results37 cm
28 cm
26 cm
25 cm
54 cm
34 cm

Breaking Point Results

40 cm
30 cm
28 cm
30 cm
60 cm
36 cm

Some things I noted were that when it was just the glue and water it was still very thick, and it resembled the appearance of rotten milk. When I added the borax solution, it turned to a putty-like substance that was squishy, white, wet, moist and rubbery for all three trials. They were all a lot bigger than when we did this same lab last week. The second was firm and sticky, while the third one was very squishy and wet the entire time. I rejected my hypothesis "if the polymer is most flexible and bouncy in trial 2, then the borax is responsible for it because trial 2 has more borax solution in it." because it was not accurate. The third trial was a lot more flexible, but less bouncy.

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