Polymer Lab Group Investigation

Problem:

When cornstarch is added to borax, water, and white glue, what will the outcome be as compared to the original lab (borax, water, and white glue)?

Hypothesis:

When the cornstarch is added to borax, water, and white glue, the cornstarch will make the mixture more difficult to pull apart because it is a better cross-linker than the borax alone. This is because it can be broken down into two compounds: Amylase and Amylopectin. Amylase is the enzyme that starts the breakdown process of starch into sugar. Amylopectin is the other chemical in starch. Together they can connect the borax like a cross-linker to create a polymer. I think that the cornstarch with the borax will form a stronger link in the glue and it will break less easily. This may also make the ball bounce higher because it is stronger.

Results and Observations:

My hypothesis was partially correct. The bond between the glue was stronger. I was also incorrect. The final ball was stickier and did not bounce as high as the prior attempt. When the mixture was first combined, it stretched, but would not stay in one piece. There was much less water and borax added to the new mixture which I thought would make the ball less wet and might make it bounce higher. It proved that this was not the case. The moisture from the glue and the water made the ball very wet feeling. The cornstarch had a similar texture to flour in that it was soft, but also had chunks in it which caused the mixture to be very inconsistent and bumpy. At first, it only stuck to my hands and would not stick together similar to the texture of marshmallow. After about 10 minutes of rolling and shaping the ball, it became less sticky and would form into a ball. It was not fully dry or solid, but felt like more of a doughy texture. Because the material would not dry out, we split it in half and put one of the pieces in the refrigerator. The other half we kept out and rolled into a ball and tried to dry out as much as possible. We conducted a test to see how high the rebound of the ball was at room temperature. We lined the ball up with the 30 centimeter mark on a ruler. When we dropped the ball, it only bounced between 2-3 centimeters. This was not very surprising after creating the ball because even though it may seem like it would be a similar texture and density of the glue, borax, and water polymer, it was very different feeling in reality. After 10 minutes of being in the refrigerator, we extracted the half of the ball from the refrigerator. When we took it out we found that the outside felt glossy and smooth. The inside however, was still very sticky when we rolled it out. When this was put to the rebound test, it bounced about 2 centimeters. It was a little bit more moist than the room temperature ball. We conducted one more test with the two balls. We stretched them both out as far as they could go. They were both very pliable, but the room temperature ball stretched about 2 inches farther before snapping. As compared to the borax, water, and glue solution, this was more moist, pliable, and less bouncy. It was stronger and broke less easily. It held its shape much better than the other polymer did.