Polymers have existed since the advent of life on earth. Natural rubber is still obtained from the rubber plant, and deposits of natural bitumen are also familiar. However, for present day engineering applications, very few natural polymers are likely to be specified, so attention must be focused on the synthetic variety, the earliest of which was a crude form of phenolic resin originating over 100 years ago. Since that time, development of polymers has posed a continual challenge to the suppliers of chemicals; the challenge also extends to designers who are perhaps not, as a group, as familiar with the ramifications of polymer technology as they are with more traditional materials. Any such difficulties as exist should be laid at the door of our educational system, despite the existence of many texts on the subject.

Polymers, as a class and in the present context, are chemical compounds based on carbon atoms; the compounds are complex, so cannot be defined as precisely as, for example, common table salt. A single polymer molecule might typically comprise many thousands of carbon atoms joined one to another, with the remaining available chemical bonds attached to other atoms such as oxygen, hydrogen, chlorine, nitrogen and sulphur, to mention just a few possibilities. To make a crude analogy, an assemblage of polymer molecules can be likened to a plate of spaghetti which has been well stirred ready for consumption.