Engineering Polymers

Engineering polymers:

Polymers is the micro molecules built by linking together the large number of the small molecule. The small molecules called monomers.

On the basis of the occurrence they are two types:

Natural  polymer

The polymer which are found in nature called natural polymer; such that starch, cellulose etc.

Synthetic  polymer

The polymer which can be prepared in laboratory  are called synthetic polymer. It can be classified into two types :

  • Inorganic polymer
  • Organic polymer

Inorganic polymer

They are giant molecule containing atoms except carbon in main chain. Atoms linking together by covalent bond. The properties of the inorganic polymer are given below:

  • They only soften and melt at the high temperature and they do not burn except Sulphur containing polymer.
  • Inorganic polymer which posses crosslinked structure are usually stiffer more brittle than organic counterparts.

Due to the crosslinked structure the chain segments are short or not flexible and they are allow swell reversibly in appropriate solvent.

  • These polymer contains large number polar monomers so it always soluble in polar solvent.
  • The tensile strength of inorganic polymer is less than organic polymer.

Types of inorganic polymers

Polyphosphazenes

Their general formula is given below:

If R = Cl then it is called polyphosphonitrile chloride

If R = OCH3 then it is called polydimethoxy phosphazenes         

If R = OC2H5 then it is called polydiethoxy phosphazines

Preparation of polyphosphonitrile chloride

They can be prepared by the reaction between ammonium chloride with phosphorous pentachloride in presence of benzoyl chloride at 250 degree celcius.

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