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Lost at sea diaries
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In the Rough Science programme Lost at Sea, the Rough Scientists Ellen and Kathy are given the task of making a life-jacket. They decide to use kapok to fill the jacket but need to make it waterproof so the contents don’t get wet. Zanzibar has a rich variety of plants and on one of her trips inland Ellen spotted some rubber trees – so they know they can get some fresh latex, but the problem is how to make this cover the life-jacket to give a strong but flexible barrier. The answer is Vulcanisation, precipitating out the rubber particles, mixing them with sulphur and heating the treated material over a fire.
To find out more about the process of vulcanisation read the following extract from the second level OU course Our Chemical Environment (ST240).
Many synthetic and natural fibres can be stretched, as we can see in the making of polymer fibres:
The main difference between rubber and other fibres is that rubber goes back to its previous shape and size. We can see that stretching a fibre aligns the polymer chains. In fibres, this alignment allows forces such as those of hydrogen bonding between chains to have an increased effect, and they will be strong enough to hold the fibres in their stretched, aligned position. In rubbery polymers (elastomers), we find there are large and bulky groups along the chains, and these prevent the chains from packing together so closely. As the chains are further apart, there are not the same forces between them to keep them in the uncoiled arrangement. This weak interaction between polymer molecules is not enough to keep the rubber in its stretched position so it reverts to the original coiled state.
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Content last updated: 01/02/2005
