Rubber Heat Reaction

How does rubber material react when exposed to high levels of heat?
Introduction
Rubber bands originated from the sap of rubber trees which are found mostly near the equator in humid climates. Most of the rubber bands today are made from synthetic materials, combining petroleum by products in a reactor with soapsuds to produce a milky liquid latex.
Hypothesis
Our hypothesis of how a rubber material will react when exposed to high levels of heat is, that the rubber material would melt and then it becomes smaller in size.
Materials
Several large rubber bands
Hair dryer
A small toy or solid item that can be attached to the rubber band and that isn't made of rubber
Doorknob or hook (such as a picture hook... something to hang the rubber band from).
Tape measure
Pen
Journal (to record your results)
Method
1. Hang the rubber band on a doorknob or hook.
2. Attach the toy or small object to the rubber band (make sure it's not made of rubber). It should be attached in a manner that allows the item to "hang" from the band. At this point you should have a dangling object hanging from the middle of the band that's attached to the doorknob or hook.
3. Use the tape measure to measure the distance from the floor to the bottom of the dangling toy or object. Record the result in your journal.
4. Carefully heat the rubber band with your hair dryer, making sure that the heat is focused on the rubber band as much as possible. This step shouldn't take too long, so be careful not to melt the band (or your dangling object).
5. Use your tape measure to once again measure the distance from the floor to the bottom of the dangling object. Record the results in your journal.
6. Compare the results from the first measurement against the results from the second measurement.
Observation
Why do rubber bands shrink instead of expanding?
Rubber bands contract when heated because at the molecular level, they comprise of entangled polymer chains that become more densely intertwined..
Explaining the phenomenon
As the heat of the hair dryer increased and the rubber material was contracting and shrinking but we could not see it shrinking before our eyes
What would happen if you hung the object with a piece of string?
The string will burn and it wouldn’t shrink.
What about if you used a metal wire?
The wire would be really hot but still it wouldn’t shrink.
Can you give some examples of real-life situations where heat can affect rubber objects?
Hot tires on hot pavement in summer
Result
When we measured the distance from the floor to the end of the toy it was 90.2cm. After applying heat we measured it and this time the distance was 90.3 cm so that means that the rubber band shrunk in size by 1mm.
Conclusion
Now we know that when rubber is exposed to high levels of heat, it shrinks. If we applied even more heat the rubber band would have melted.
Vocabulary
Synthetic materials- materials that are made from combined chemicals, especially to imitate a natural product.
Petroleum- an oil that is refined to produce fuels including petrol, paraffin and diesel.
Soapsuds- the froth produced by soaps or detergent.
Sleeve- a tubular piece that is forced or shrunk into a cylindrical bore to reduce the diameter of the bore or to line it with a different material.