Expandable polystyrene EPS process

The polymerisation then follows a schedule that raises the temperature of the reaction mixture stepwise towards nearly total conversion of the monomer into the polymer. Pentane, a mixture of normal and isopentane, is added as a blowing agent during the course of the polymerisation. 

The type and the quality of the suspension agent system and the reaction temperature profile are critical to ensure good suspension stability, bead size distribution and a high conversion rate. These parameters also influence the properties of the final product. An aliphatic brominated compound is specifically added for the production of flame-retardant grades. 

At the end of the polymerisation, the suspension is cooled the expandable polystyrene beads are separated by centrifugation, washed and then dried at a relatively low temperature of 35 °C. 

Following this, the beads are then screened into several bead size fractions corresponding to the various commercial needs and applications. They are then coated to improve both processing characteristics and final performance of the product. Finally, these expandable polystyrene beads are packaged in containers or silos for shipment. 

Polymerisation type Radical polymerisation in aqneons snspension 

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