Polymer Lab Group Investigation

State the Problem:
Will adding extra borax or using less affect the rebound of the polymer?

Hypothesis:
One teaspoon of borax will leave the glue somewhat sticky and unformed. Adding extra borax will make no difference because the water will be saturated.

Materials:

40 mL white glue (polyvinyl acetate)
525 mL water
1 stirring rod
1 500 mL beaker (we used a 600 mL beaker)
1 200 mL beaker (we used a 250 mL beaker)
1 graduated cylinder
4 tsp. borax (hydrated sodium borate)

Procedures:

Begin by gathering the necessary materials. Measure 400 mL of water into the large beaker. Be very exact when measuring. Add one teaspoon of borax to the liquid and stir until the water is saturated and the most of the powder has dissolved. Set this beaker aside. Place 40 mL of glue into the small beaker. Next, slowly and carefully measure 25 mL of the borax solution into the graduated cylinder. Pour this part of the solution into the glue while a lab partner stirs continuously. If the solution is not stirred continuously, the experiment may not be as successful. Stop stirring when most of the water has been absorbed into the glue.

Test the rebound of the polymer. Drop it from 30 cm five times and record the average rebound height.

Repeat the process with a new polymer, but the same beaker of borax solution. Add three more teaspoons of borax into it, for a total of four teaspoons. Conduct the same tests.

Results/Observations:
The first polymer was very sticky. It left a lot of extra solution in the beaker, and it didn't bounce well. It's rebound was 7 cm. One thing we noticed was that as it dried, it became a little less sticky.

The second polymer was a mess at first. It was really tight and hard in some spots, and still plain glue in others. After we placed it in the solution again, it became far more evenly solidified, and worked very well. However, this one also left a lot of extra solution in its beaker. It had a rebound of 11.6 cm when we tested it.

Conclusions:

I accepted my the first part of my hypothesis, because the polymer did just that: it was a sticky mess. However, I rejected the second part of my hypothesis, because the second polymer was actually a little bit slimy/squishier than the polymer from the class lab we did using these materials. The extra borax didn't dissolve into the water because it was saturated, and I think it made a difference because there was a lot of borax floating in the water. There were a lot of problems with our lab. For instance, we started by quickly rewriting our lab because we couldn't get the milk we needed for our original lab from the school. Another problem was being slowed down by the low glue supply. We went through six bottles to get enough glue for both polymers, because there was so little left in each bottle! We also were a little bit anxious to test the polymers, and we had to return them to the solution after we pulled them out because they hadn't been in long enough. This really messed us up, and I've learned to be very patient in labs, because the results can often depend on it. I've also learned that sometimes plans need to be changed, so I should always have a backup plan and be flexible.