Re: What holds rubber together?

My friends and I have an ongoing debate about what holds the rubber on the soles of your shoes together. I say it is some sort of chemical and they say that when melted it just forms into a mold. It all started when a piece of a friends shoe tore away. Please help end this debate. I would greatly appreciate it, we cannot find the answer anywhere!

Fortunately (or perhaps unfortunately), you are both correct. The rubber in the sole of your shoes is a polymer. Check out http://www.pslc.ws/macrog.htm This web page is set up with different levels. Level one is like a shopping mall and you can go to the shoe store and learn what polymers go into different shoes.

The polymers are the chemicals you said shoes are made of and there are billions of these polymers in a shoe sole. Think of the polymers as spaghetti noodles. When spaghetti noodles are warm, they can slide past each other; when they cool, you get a large clump of noodles that are entangled. This is how the polymer is molded (what your friends argue). The polymer is heated so that the chains can slide past each other, when cooled into a mold the chains are physically entangled and its becomes one large "clump". These physical entanglements give the material (the clump) its properties.

Now depending on what the clump is to be used for, various things can be done to the clump. Before the heated polymers chains are cooled, different materials can be added in to add color or more elasticity (springiness). After the material is cooled, it can be crosslinked so that the individual polymer chains are now chemically attached to each other (this is how car tires are produced--through a procedure called vulcanization).

So, now you and your friend can argue that you are both correct! Hope this answers your question.