POLYMERS :

Polymers are macro molecules built-up by the linking together of large number of small molecules called manomers. The number of repeating units in a polymer is known as the degree of polymerization.



In general, most of the polymers fall into the 5000-200,000 molecular mass range.

Properties:

Physical:   

    Polymers are in the form of crystal or amorphous or crystallites embedded with an amorphous matrix.

Thermal:

    Below glass transition temperature, they are in hard condition and above the glass transition temperature they become soft nature.

Optical:

    The appearance of a transparent plastics and opaque plastics are characterized by its transmittance or reflectance properties respectively.

Chemical:

    Chemically resistant.

Eg:

1.    Polymers having polar groups are chemically resistant to non-polar solvents.

2.    Similarly, polymers having non-polar groups are chemically resistant to polar solvents.

Electrical:

    In general, Polymers are insulators due to their wide band gap. Now a days, we can manufacture conducting polymers by synthetic methods.

Classifications:

     On the basis of manomer unit.

1.     Homo polymer
2.     Co-polymer.

Homo polymer:

    The are made up of identical manomer unit.

           -M-M-M-M-M-

Co-polymer:

    They are having different kind of manomer units.

Important classification:

    Polymers can be classified into following three types.

    Plastics (resins)

    Elastomers (rubber)

    Fibers (nylon).