Composition Of Plastics

Resins

Resins are typically organic polymers of high molecular mass, but they often contain other

substances. They are usually synthetic, most commonly derived from petrochemicals(synthetic

organic solids), but many are partially natural(semi-synthetic organic solids).

The vast majority of these polymers are based on chains of carbon atoms alone or with oxygen,

fur, or nitrogen as well. The backbone is the part of the chain on the main"path" linking a larg

number of repeat units together. To customize the properties of a plastic, ditterent molecular groups

are"hung"from the backbone(usually they are"hung "as part of the monomers before linking

monomers together to form the polymer chain). The structure of these"side chains" influences th

properties of the polymer

Additives

Most plastics contain other organic or inorganic compounds blended in. The amount of

additives ranges from zero percentage for polymers used to wrap foods to more than 50% for

certain electronic applications The average content of additives is 20% by weight of the polymer

Since many organic polymers are too rigid for particular applications, they are blended with

plasticizers, oily compounds that confer improved rheology. Stabilizing additives" include fire

retardants to lower the flammability of the material. Colorantsare common additives, although

their weight contribution is small. Fillers improve performance or reduce production costs. Many

plastics contain fillers, relatively inert and inexpensive materials that make the product cheaper by

weight. Typically fillers are mineral in origin. Some fillers are more chemically active and are

called reinforcing agents.