XPS

Extruded polystyrene hard foam (XPS) is produced on extruding machines in the form of continuous foam billets. In the extruder polystyrene is melted and, after addition of CO₂ (carbon dioxide) or in other countries HFCKW (partially halogenated fluorochlorohyrocarbon) as a foaming agent, extruded through a nozzle with wide slit to obtain a foam billet. Thicknesses between 20 and 200 mm can be produced. After running through a cooling zone the billet can be sawed into panels in a subsequent machine and the edges formed. The foam skin remains on the outer surfaces of the panels. When used for "insulation under plaster" the foam skin is either removed, giving the panel a rough surface, or the surface is embossed to obtain a waffle pattern. After cutting to size the panels are aged to ensure dimensional consistency.

Properties :
Extruded polystyrene hard foam is a closed-cell foam material which absorbs only minimum quantities of moisture. XPS is only slightly resilient and is resistant to rotting and aging. Extruded polystyrene foam is not resistant to UV light.