Macromolecules exist in a variety of aggregate states according to the structure, temperature and other environmental conditions. Four of these states are rubbery, glassy, crystalline and liquid. One polymer may exist in all of these states or some of them. Polymers are different compared to materials with lower molecular weight, because they normally exist in more than one state for the same sample and in rare special condition exhibit 100% crystalline state. Therefore, in one polymer sample, some may exist in the form of rubbery or glassy portion and some in crystalline portion