Short foam overview

 

For the modeler three kinds of foam play a major role:

·         EPS

·         XPS

·         EPP

 

Styropor - EPS (expanded polystyrene)

Plastic resin is expanded, then molded together to form a closed-cell material that uses trapped air as its insulating medium. Expanded polystyrene (EPS) foam is a closed-cell insulation that's manufactured by "expanding" a polystyrene polymer; the appearance is typically a white foam plastic insulation material.
EPS is mostly known as Styropor®. However, this is the trademark used by BASF. Expanded polystyrene is foamed with steam and needs to be stored and dry before it is cut. Styropor® is available in various quality standards. EPS densities for practical civil applications range between 11 and 30 kg/m3. The melting temperature of polystyrene is 150°C.

Styrodur - XPS (extruded polystyrene)

Plastic resin is liquefied, then extruded through a die and expanded to form a closed-cell material that uses trapped air as its insulating medium.
Extruded polystyrene (XPS) foam is a rigid insulation that's also formed with polystyrene polymer, but manufactured using an extrusion process, and is often manufactured with a distinctive color to identify product brand. Variations in the slot die allow board thicknesses between 20 mm and 200 mm.
Polystyrene foams start to soften and shrink from 100°C. They melt at even higher tem-peratures. If the melted mass gets further heated, ignitable decomposition gases are created at about 350°C. Without a flame source and temperatures above 450 to 500°C lead to the ignition of the decomposition products. Up to these temperatures, polystyrene foam is not self-ignitable.

XPS is known under numerous trademarks, e.g. Styrodur® and Styrofoam®, and is manufactured in various colours by various companies, e.g. Dow Chemicals and BASF. XPS is foamed in extruders using LPG. In contrast to expanded polystyrene it consists of a fairly homogenous cell structure. It weighs from 25 kg/m³ to 50 kg/m³. Compared to expanded materials, EPS is relatively pressure resistant.

EPP - Expanded Polypropylen

Styrofoam Expanded Polypropylene (EPP) EPP is extracted from oil and is available in black, white, red, blue, green and yellow weighing between 15 and 60 kg/m³. EPP is light and yet very stable and can take on virtually any shape. It is temperature-resistant from -40°C to +110°C and also resistant to chemicals, so that it can be treated with veneers containing solvents.