Monday, January 7, 2013

Glue and Borax Lab

Title: Cross Linking Elmers glue with Sodium Borate

Problem: How is a polymer formed by using glue and sodium borate?

Hypothesis:  If the glue and borax and water is mixed together, the molecules will combine into a chain making it stick to itself, feel rubber, and bounce because when the molecules form a chain, it makes it a polymer and polymers have those properties.

Materials:

  • 500mL Water
  • 25mL Elmer's glue
  • 1 Tablespoon
  • 1 tsp. Borax
  • 1 graduated cylinder
  • 1 600mL Beaker
  • 1 250mL Beaker
  • Stirring rod


Procedures:
Fill the 600mL Beaker with 100mL of water. Then add one tablespoon (about 3 teaspoons)  of borax powder. Stir until the borax is completely dissolved. the borax did not completely dissolve in ours. Measure out 25 mL of Elmer's glue into the 250mL beaker. Add 5ml of water and gently stir. the glue solution did not get thicker, but a little bit thinner. Mix 40mL of the borax solution to the glue solution. Stir vigorously and watch the new solution change in texture and appearance. Our new solution very thick and looked creamy.  Take out the polymer and dump out the extra runny liquid. At first, ours was very wet, but as we performed the tests, it dried. Also, it was very slimy. The polymer had a faint glue smell to it.After this there are test that can be performed. The first test done was the slime rating. 5=very slimy, and 1=not slimy. Our slime/polymer was about a 2 or 3. The next test was the slow poke test. Roll the polymer into a ball and slowly poke your finger into the polymer. After that we did the quick poke test. Roll the polymer into a ball and quickly poke your finger into the polymer. Next was the slow pull test. Slowly pull apart the polymer. After that test was the quick pull test, the bounce test, and the blob test.  


Observation / Results:
slow poke- Finger is pushed into the slime, it wasn't super easy and it required some force.
quick poke- Finger does not go into the goop, finger goes to one side and the goop to the other.
slow pull-Expands, can pull apart like a spring but only went back together after some pressure
quick pull- Comes apart easily and quickly
bounce- 10 centimeters (small blob bounces higher, big blob bounced lower)

This image shows the glue  and borax before it is mixed.

This images shows the glue and borax forming the polymer as it is mixed because they clong together.


Analysis:
1) How is slime visco-elastic?
Our slime was visco-elastic because when being formed, it was thick,  and had a sticky consistency. It could be stretched like elastic.

2) What are the physical properties that change as a result of the addition of sodium borate to the Elmer's glue?
When the borax solution was added, the glue solution got thicker and became more solid.

3) What would be the effect of adding more sodium borate to your cup(your thoughts only)?
I think that adding more sodium borate to the glue solution might make more slime, and the process of changing from a liquid to a solid might go faster. There might not be as much liquid left.  

4) After making the observations on the dried glue, how does the water affect the elasticity of the polymer? What is elasticity?  
Elasticity is basically how stretchy something is. The technical definition is the tendency of a body to return to it's original shape after being stretched or compressed. If there is more water,then the elasticity is usually higher. If there is too much water, there is too much extra liquid left over.

5) Find and circle the repeating unit in the polymer below.  
The repeating unit is vinyl alcohol.


6)What is the structural formula of the poly(vinyl alcohol) monomer circled above?
CH2CHOH

7) In the picture below, circle the borax cross linking agent.


Conclusion: The solutions did mix and turned into a polymer after the water was gone, so my hypothesis was proven correct. It did bounce and had a very rubbery texture. It also stuck to itself very well and was hard like a big piece of rubber. It was not very stretchy when it was dry, but it was when there was a lot of water in it. There were not any errors in this experiment and my hypothesis was completely correct. To modify this experiment, maybe we could have observed the polymer under different temperatures.

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