Before you read this, I suggest you read post 20.7. Natural rubber is a polymer consisting of isoprene molecules joined as shown in the picture above. It is obtained from the sap of rubber trees which consists of the polymer molecules dispersed in water. The water is removed and the polymer rolled into thin sheets.… Continue reading 20.8 Rubber

Before you read this, I suggest you read posts 16.30 and 16.33. At high pressure, in the presence of a suitable catalyst (post 16.33) ethene molecules (see picture above) join to form polyethene or polyethylene or polythene, whose formula is shown below. Notice that each carbon atom is still bonded to two hydrogen atoms, as… Continue reading 20.7 Polymers

In posts 20.2, 20.3 and 20.5, we thought about stretching a long, thin wire. This post continues the topic. But it is about the work done (post 16.20) in stretching the wire and what happens to the resulting potential energy (post 16.21). When a force stretches the wire, it moves its point of application and… Continue reading 20.6 Elasticity

Before you read this, I suggest you read post 20.2. Let’s return to stretching the long, thin wire of post 20.2. In posts 20.2 and 20.3, we neglected that the wire becomes slightly thinner as it gets longer. The reason for thinking about a long, thin wire was that this effect is not easy to… Continue reading 20.5 Poisson’s ratio