Manufacturing Expanded Polystyrene (EPS)

May 5, 2011Leave a reply

Expanded Polystyrene (EPS) is a closed cell, rigid foam plastic used in insulation and packaging products.  Since EPS is a closed cell structure, aging has no effect on the long-term thermal resistance.  A common application of EPS in today’s society is the foam coffee cup, which effectively protects your hand from the hot or cold liquid within.

The manufacturing of EPS does not involve the use of ozone depleting CFCs or HCFCs.  EPS starts off as small resin beads, having the consistency of table salt.  These beads are expanded on the order of 50 times their original size in a pre-expansion process using steam and agitation.  The pre-expanded resin beads are then dried, and aged for up to 48 hours to allow the pressure within the beads to equalize, and air to fill the millions of void spaces.

Once the aging process is completed, the expanded beads are molded into blocks, and then cut to the desired product thickness.  The finished EPS is approximately 90% air.  It is rigid, moisture resistant, has a low thermal conductivity, and can be cut into sheets or slabs to meet specific design reqiurements.

Leave a Reply