This figure illustrates the chemical structure of polyethylene, i.e. (CH₂CH₂)_n, where n is a large number. Sections of the polyethylene structure have been drawn out to better show how the repeating CH₂ units are linked together by a bond that is illustrated by a line. This starts to show the chain structure of polyethylene and also that there are so-called cross-linking groups connecting these chains together, in this case simply another CH₂ unit.

◄ 7.1 Some aspects of the science of plastics