Plastic behaviors

A knowledge of the chemistry of plastics can be used to help with the understanding of the performance of designed products. Chemistry is the science that deals with the composition, structure, properties and transformations of substances. It provides the theory of organic chemistry, in particular our understanding of the mechanisms of reactions of carbon (C) compounds.

The chemical composition of plastics is basically organic polymers. They have very large molecules composed of connecting chains of carbon (C), generally connected to hydrogen atoms (H) and often also oxygen (O), nitrogen (N), chlorine (CI), fluorine (F), and sulfur (S). Thus, while polymers form the structural backbone of plastics, they are rarely used in pure form. In almost all plastics other useful and important materials are added to modify and optimize properties for each desired process and/or product performance application.

The chemical and physical characteristics of plastics are derived from the four factors of chemical structure, form, arrangement, and size of the polymer. As an example, the chemical structure influences density. Chemical structure refers to the types of atoms and the way they are joined to one another. The form of the molecules, their size and disposition within the material, influences mechanical behavior. It is possible to deliberately vary the crystal state in order to vary hardness or softness, toughness or brittleness, resistance to temperature, and so on. The chemical structure and nature of plastics have a significant relationship both to properties and the ways they can be processed, designed, or otherwise translated into a finished product.

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