Polymer Technology

In suspension polymerization styrene is dispersed in water in the form of small droplets by stirring The addition of suspension agents such as polyvinyl alcohol, alkaline phosphates, or celluloses is necessary to stabilize the organic phase Polymerization must be started with radical-forming initiators because the process temperatures (80100°C) are considerably lower than those of continuous bulk polymerization.
The main advantage of suspension polymerization is that the heat of polymerization can easily be removed via aqueous phase. A high degree of conversion can also be achieved. However the polystyrene beads must be repelletized after the separation of the water and drying to satisfy marker requirements. This makes suspension process uneconomical. Very few of the older plants based on this technology are still running commercially.

The techniques used in polymerization depend upon following factors:

1. Physical form of reactants; gas, liquid or solid.
2. Solvents used
3. Type of polymerization mechanism
4. Required physical form of polymer; solid, emulsion, solution

These factors lead to different polymerization techniques.

1. Bulk Polymerization
2. Solution polymerization
3. Suspension polymerization
4. Emulsion polymerization
5. Melt polycondensation
6. Solution polycondensation
7. Interfacial Condensation
8. Solid and Gas Phase polymerization