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Pre-expansionPre-expansion, that is the physical-chemical process that leads to the formation of the polystyrene beads, takes place by heating the polystyrene – the raw material – without using CFCs. The beads thus obtained are then treated with water vapour at temperatures above 90°C to allow the pentane they contain to expand causing an increase in their initial volume by up to 20-25 times, forming an internal closed cell structure that holds air and gives the product its excellent thermal insulation properties.

Maturing period

After pre-expansion the beads are subjected to a period of ageing and then are conveyed to silos to be air dried, here excess moisture is removed. This provides the stability required for the next stage of the process.