Q. Properties of plastic?

Their great variety of physico- chemical and mechanical properties, and ease with they can be made into various articles have found plastic their wide application in the engineering and other industries.

• Their comparatively low density (1 to 2 g/cm3). Substantial mechanical strength, higher strength - to-weight ratio and high anti friction properties have enabled plastic to be efficiently used as substitute for metals, for example, non ferrous metals and alloys- bronze, lead, tin, Babbitt etc., for making bearing.

• With certain special properties (silent operation, corrosion resistance etc.,), plastic can sometime replace ferrous metals.

• From the production point of view, their main advantage is their relative low melting point and their ability to flow into a mould.

• Simple processing to obtain machine parts. Generally there is only one production operation required to convert the chemically manufactured plastic into a finished article.

• In mass production, plastic substitute for ferrous metals allow the production cost to be required by factor of 1.5 to 3.5 and for non- ferrous metals by a factor 5 to 20.

• Good damping capacity and good surface finish of the product.

• the high heat and electric insulation of plastics permits them to be applied in the radio and electrical engineering industries as dielectrics and as substitute for porcelain, ebonite, shellac, mica, natural rubber, etc..