Cross-Linking Elmer's Glue With Sodium Borate (Slime Lab)

Cross-Linking Elmer's Glue With Sodium Borate (Slime Lab)

Today in science I learned about monomers, polymers, and cross-linking agents. A monomer is singular part that can be chained to other monomers to form polymers. Polymers are all around us. All plastics are polymers. A cross-linking agent is something that promotes the formation of stronger polymers usually through a chemical reaction. My group and I, (Kira Gedris and Jake Lieberman), did a lab which tested what happens when you mix water and Elmer's glue, the two monomers, with Sodium Borate (or Borax), the cross-linking agent. My hypothesis was that the monomers will react with the borax to form a solid polymer. 

These were the materials needed for the lab:

500 mL water

25 mL Elmer's glue

1 tsp. borax

2 drops food coloring

1 graduated cylinder

1 600 mL beaker

1 250 mL beaker

1 stirring rod

This was the procedure:

1. In the 600 ml beaker, measure 100ml of water

2. Add 1 tablespoon of borax powder to 100 ml of water

2. Measure 25 ml of Elmer's glue in the 250 ml beaker 

4. Measure 5 ml of water and add it to the Elmer's glue 

5. Add 2 drops of food coloring to the Elmer's glue 

6. Gently stir the glue-water solution

3. Measure 40 ml of borax solution with the graduated cylinder

8. Pour the 40 ml of borax in the glue solution 

9. Stir vigorously

10. Dump liquid and runny stuff, remove the polymer from the 250 ml beaker 

11. Observe the polymer

Here is the diagram of the structure of the elmer's glue molecules and the borax molecules and what the structure looks like when you add them together:

Here is a diagram of monomers, (water and glue), added with the cross linking agent, (borate) to create a polymer. Note: The cross-linking agent is circled:

Here is a picture showing the beaker with the polymer solution being mixed:

Here is a picture of the Borax being mixed with water:

Here is a picture of what the polymer looked like: 

These are some of the characteristics of the polymer and the analysis of the data:

Description: smells like glue, feels like a wet deflated balloon, and it's very squishy

Slime Rating(from 1-5, 1 being the least slimy and 5 the most): 5

Slow Poke Test: When the slime was poked slowly, the finger went into the goop easily and then the slime molded around the finger

Quick Poke Test: The finger didn't go through the slime. It glided off to the side of the polymer.

Slow Pull test: The smile pulled apart with ease.

Quick Pull Test: Similar to the slow pull test, the slime separated with ease. 

Blob Test: In this test we were supposed to lay the slime on a flat surface then time it until it flattened out. This test was inaccurate because the slime did not flatten out all the way, but only on the bottom where the table was. 

Bounce Test: The slime was very bouncy and bounced repeatedly after being dropped. 

Other Observations: 

The glue-water solution was pretty constant and thick before we added the borate to it. The glue was thick and clumpy after the borate was added. This is because the cross-linking agent (the borax) cause some of the glue to form a chain and create a strong structure, which was the polymer. 

Elasticity is the tendency of a body to return to its original shape after it has been stretched or compressed. What increases the elasticity of the polymer because it makes the glue more easily changeable, so it can react faster with the borax. 

The slime is viscoelastic because it is both thick and elastic.

Conclusion: 

My hypothesis was supported because if borax is added to the water-glue solution, then it will form the strong polymer slime because monomers create polymers. If we added more borax to the solution, there would be more elasticity because there was more cross-linking agent. Some problems that could have altered our info would be that the mixing of the borax and water wasn't mixed well enough, and that the polymer wasn't stirred right to create the strongest polymer possible. This test will help me in future tests because I will know that weak things, like monomers, can combine to create strong things,like polymers. Also, I will know that by adding the cross-linking agent, the strength of the polymer will increase. An example of where I would use this information would be if I need to create a stronger plastic, I would increase one of the chemicals used to make (specifically the cross-linking agent), and I would have made a stronger polymer. Over all, this lab gave me a greater perspective of what make up certain things, and how I can apply my knowledge of monomers and polymers to real life.