- Paper, pens and other stationary for a hand-drawn poster.
- Computer with a word processor or similar software.
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Exploring Everyday Chemistry
PlasticisersWhen you have selected your chosen product, look out for the presence of plasticisers. A plasticiser is a substance which when added to a material, usually a polymer, makes it flexible, resilient and easier to handle. For example, polyvinyl chloride (PVC), [-CH2CHCl-]n, is an extremely hard plastic, and to make it more flexible, plasticisers are added. These are small organic molecules that embed themselves in-between the PVC polymer chains so they cannot interact with each other as well. This reduced interaction ensures that the polymer is more pliable. In PVC, the most common plasticisers are a class of esters called phthalates. They are the preferred plasticiser found in, for example, trainers, because of their strong performance, cost-effectiveness and durability. The characteristics of an individual phthalate often make it well-suited to a specific product, allowing manufacturers to meet unique requirements for its use (function and safety specifications), appearance (texture, colour, size and shape), durability and wear.Phthalates are only slightly volatile, and so tend not to evaporate and they have little or no odour. Despite this, there have been some concerns over the presence of phthalates in ‘new car smell’. The reason for the concern is that some of these compounds have been found to interfere with normal sexual development in male rats. Some scientific studies have indicated that phthalates behave as endocrine disruptors in human beings, that is, they interfere with our normal hormonal mechanisms. Consequently, the use of phthalates with relatively low molecular weights has been restricted in the European Union. In contrast, scientific studies on phthalates with high molecular weights (called high phthalates) have concluded that they do not pose a risk to human health at typical exposure levels.The health concerns associated with phthalates, coupled with the fact that they are not chemically bonded to polymers and so can leach out into the environment, has inspired the development of alternatives and this continues to be an active area of research.
For the recordThe impact of chemistry on sport is nicely illustrated by the 100 metres sprint. At the Berlin Olympics, in 1936, Jesse Owens ran the race in 10.3 seconds. This is slower than Usain Bolt’s record of 9.58 seconds in 2009. However, Owen’s track surface was made of cinders, he wore heavier and less flexible leather shoes, and his “starting block” consisted of two holes in the cinders that he had to dig with a trowel. According to a biomechanics analysis, if Owens had used a real starting block, worn modern shoes, and run on a rubber-polyurethane surface, he would have been within a single stride of Bolt!To illustrate the point, this clip shows how a modern sprinter fared on a dirt track with no starting bloc.
This is an additional video, hosted on YouTube.
Exploring Everyday Chemistry
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