Extruded polystyrene foam is a rigid foam with a very low 33kg/m³ density that can be used as a structural core in lightweight constructions, as a dissolvable/sacrificial former or core, and for general modelmaking and craft applications.
Extruded polystyrene foam cuts extremely well by hot-wire, making it the foam of choice where hot-wire cutting is the preferred way of profiling the foam, such as RC aeroplane wings. It is also dissolvable by solvents such as styrene and acetone which can be used as a means of dissolving and extracting the foam where it has been used as a temporary former or sacrificial core for projects like fuel tanks.
The foam listed on this page was formerly known as Dow Styrofoam but has recently been renamed to Ravatherm XPS X H LB but only the name has changed; this is the same product, and same performance as the original genuine Dow Styrofoam.
Advantages
Very low density - At 33kg/m³, this extruded polystyrene foam is one of the lowest density core materials available (together with our 30kg/m3 Rohacell)
Perfect for hot-wire cutting - Polystyrene foams, including extruded polystyrene, are one of the only foams suitable for hot-wire cutting, and can be quickly and accurately cut using this method (by hand or CNC).
Can be dissolved by solvents - Polystyrene foam, including extruded polystyrene, can be easily dissolved by solvents such as acetone, MEK and styrene. This allows polystyrene to be used as a sacrificial core, laminated over (using a resin such as epoxy) and then dissolved and removed to make a hollow structure, such as a fuel tank.
Considerations
Lower compressive strength - Although the foam offers a very low density and the advantage of easy cutting by hot-wire, it does have a lower compressive strength, relative to its density, compared to foams more often used as structural cores, such as closed cell PVC foam, PMI foam (i.e. Rohacell) and PET foam (i.e. 3DCore).
Dissolves in contact with some resins - Polystyrene foam will dissolve immediately in contact with solvents such as acetone or styrene and therefore this type of foam cannot be used where solvent-borne resins, such as polyester and vinylester, will come into direct contact with it. Epoxy resin does not contain solvents and will not attack polystyrene foam.
Does not shape well by hand - Unlike polyurethane foam, which cuts and shapes extremely easily, extruded polystyrene is less easy to shape by hand and so is less suitable for pattern making than PU foams.
Suitable Uses
Extruded polystyrene has a number of physical properties which make it suitable for a wide range of different applications. As well as its use in composites as a core material, or low cost/dissolvable pattern making foam, it can also be used for general craft applications, thermal insulation, model making, buoyancy and many more.
How to Buy
Thickness
The foam sheets are 100mm thick.
Sheet Size
The foam is available to buy in sheets of 1200 x 1200mm, 1200 x 600mm, 600 x 600mm and 300 x 300mm. Please choose the size you require from the product options near the top of the page.
Sheet sizes are nominal (+/- 5mm) and due to the delicate nature of the foam, some minor surface defects may have occurred during storage and transport.
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