How Are Extruded Polystyrene Boards Manufactured?

Expanded polystyrene and extruded polystyrene board are both thermoplastic polymers extracted from two petroleum products, benzene and ethylene. The difference lies in how they are manufactured. XPS is manufactured in a process called extrusion. Plastic resin is combined with several additives and extruded through a die at high temperature. After extrusion, XPS cools and expands into its final form.

The additives mixed in the extruder (the machine used in the process of manufacturing XPS) include colorants and blowing agents. Using colorants during the extrusion process makes it easier to distinguish different brands of XPS foam. Blowing agents have a more specific use because they allow XPS to expand after the extrusion process.

Unlike EPS, XPS is extruded into an approximation of its final form. In other words, you do not use hot wire to cut into large blocks of foam as you do with EPS. Instead, the foam you get is very similar in appearance to the final product. All that remains to be done is to trim the edges, and the product is complete. Due to the extrusion process, the thickness of XPS boards is limited. This is not the case with EPS poured into molds. Although XPS is very similar to EPS, it is actually a better insulation material due to higher energy efficiency. XPS is a closed-cell structure with no gaps or spacing between foam cells. Due to the extrusion process, the foam cells are tightly squeezed together, leaving no openings for water to pass through. Preventing water from entering through the insulation layer is crucial for maintaining energy efficiency. Water has high thermal conductivity, which means lower energy efficiency. This makes XPS foam boards superior to EPS in terms of insulation and water absorption to increase density. However, XPS usually costs a bit more because it can only be provided at high densities starting from 28Kg/m³, while EPS can start from 9Kg/m³. Due to the extrusion process that produces closed-cell foam insulation boards, XPS is harder and sturdier, with high mechanical resistance and amazing compressive strength. Neither EPS nor XPS can completely resist water vapor, but XPS does have higher water vapor diffusion resistance. Importantly, XPS is a chemically inert material, it is also very durable, able to resist the growth of fungi and bacteria. And, it has excellent dimensional stability which is crucial for any insulation material.

Due to all the characteristics of XPS, it is mainly used as foam insulation boards for building insulation, thermal insulation and waterproofing. You can use XPS insulation boards to insulate any part of walls, floors and even roofs. However, the use of extruded board is not just for insulation, although this is its main purpose. It is commonly used in architectural modeling and crafts, where you can benefit from a lightweight material that can be colored. You can use XPS to cover every wall of the house and reduce thermal bridges. In addition to covering walls, you can also use foam boards to insulate balconies, decks and all other surfaces you want to keep energy efficient.