The different manufacturing processes of Xps extruded board and Eps two polystyrene insulation materials will have a huge impact on the long-term performance of the two products.
It is important to note that these differences may cause buildings to fail to be constructed as designed.
Extruded polystyrene insulation or XPS insulation board is manufactured through an extrusion process, which involves melting plastic resin and other ingredients together. Then a liquid is formed, and these solutions are continuously extruded through a die and expand during cooling, thereby producing the extruded board.
Expanded polystyrene insulation or EPS insulation is manufactured using a mold containing small foam beads. Heat or steam is then applied to the mold, causing the small beads to expand and fuse together. This manufacturing process does not form closed-cell insulation, because there are usually gaps between each bead, and they do not touch each other.
What do different manufacturing processes mean for extruded board performance?
Water absorption rate
The interconnected gaps between beads in EPS allow water to penetrate. This reduces insulation performance because water is a good conductor of heat. This is especially true for underground and inverted roof applications, where the insulation layer will be exposed to water. In addition, please note climates with temperatures below freezing. Freeze-thaw cycles in these areas can cause water within the gaps to expand and break the bonds between beads, further reducing insulation performance. This will open up the EPS insulation layer. Due to the closed-cell structure of XPS,
Thermal conductivity
The thermal conductivity of XPS starts lower than that of EPS. This is because air is a good conductor of heat. The interconnected gaps in EPS foam conduct heat due to the air in them, therefore, you need higher density (more beads, therefore smaller gaps) to reduce this form of conduction.
Compressive strength
The compressive strength of EPS is worse than XPS. In order for EPS to achieve the same compressive strength as XPS, the density of the foam needs to be higher, therefore requiring a more burdensome manufacturing process.
English