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plastic any organic material with the ability to flow into a desired shape when heat and pressure are applied to it and to retain the shape when they are withdrawn.
Composition and Types of Plastic
A plastic is made up principally of a binder together with plasticizers, fillers, pigments, and other additives. The binder gives a plastic its main characteristics and usually its name. Thus, polyvinyl chloride is both the name of a binder and the name of a plastic into which it is made. Binders may be natural materials, e.g., cellulose derivatives, casein, or milk protein,[link widoczny dla zalogowanych], but are more commonly synthetic resins. In either case, the binder materials consist of very long chainlike molecules called polymers . Cellulose derivatives are made from cellulose, a naturally occurring polymer; casein is also a naturally occurring polymer. Synthetic resins are polymerized, or built up,[link widoczny dla zalogowanych], from small simple molecules called monomers. Plasticizers are added to a binder to increase flexibility and toughness. Fillers are added to improve particular properties,[link widoczny dla zalogowanych], e.g.,[link widoczny dla zalogowanych], hardness or resistance to shock. Pigments are used to impart various colors. Virtually any desired color or shape and many combinations of the properties of hardness, durability, elasticity, and resistance to heat, cold, and acid can be obtained in a plastic.