Sunday, June 27, 2010

Unit 3- Class 6- High Polymers (Methods of polymerization - Solution polymerization)

Solution polymerization: In this technique, monomer, initiator and chain transfer agents are dissolved in an inert solvent. The solvent helps to control viscosity increase and promote proper heat transfer.

Advantages :

1.    The viscosity build up is negligible.
2.    The heat control is easy.
3.    The agitation is easy.
4.    The polymer in solution form is used as adhesives and coatings.

Disadvantages:

1.    It is difficult to get very high molecular weight products since solvent may act as chain transfer agent thereby limit the molecular weight.
2.    The polymer formed will also have to be isolated from the solution either by evaporation of the solvent or by precipitation in a non-solvent.
3.    Removal of their final traces is always difficult.

Applications: This method is used for the production of polyethylene, PVC, polisobutylene, polyacrylonitrile etc.

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