Editing Polystyrene (section)

==== Extruded polystyrene (XPS) ====
[[File:Foam Board.jpg|thumb|upright=1.7|Extruded polystyrene has a smooth texture, and can be cut into sharp-edged shapes without crumbling]]
{{anchor|Extruded polystyrene foam}}
Extruded polystyrene foam (XPS) consists of closed cells. It offers improved surface roughness, higher stiffness and reduced thermal conductivity. The density range is about 28–34&nbsp;kg/m<sup>3</sup>.<ref>{{Cite journal|last=Al-Ajlan|first=Saleh A.|date=2006-12-01|title=Measurements of thermal properties of insulation materials by using transient plane source technique|url=https://www.sciencedirect.com/science/article/pii/S1359431106001256|journal=Applied Thermal Engineering|language=en|volume=26|issue=17|pages=2184–2191|doi=10.1016/j.applthermaleng.2006.04.006|bibcode=2006AppTE..26.2184A |issn=1359-4311}}</ref><ref>{{Cite web |title=National Commercial Corporation |url=https://www.nathanibiz.com/ti-xps.php |access-date=2022-06-18 |website=www.nathanibiz.com}}</ref>

Extruded polystyrene material is also used in [[craft]]s and [[Physical model|model]] building, in particular [[Architecture|architectural]] models. Because of the extrusion manufacturing process, XPS does not require facers to maintain its thermal or physical property performance. Thus, it makes a more uniform substitute for [[corrugated cardboard]]. Thermal conductivity varies between 0.029 and 0.039 W/(m·K) depending on bearing strength/density and the average value is ≈0.035 W/(m·K).

Water vapor diffusion resistance (μ) of XPS is around 80–250.

Commonly extruded polystyrene foam materials include:
* [[Styrofoam]], also known as Blue Board, produced by [[DuPont]]
* Depron, a thin insulation sheet also used for model building<ref>{{cite web |title=Technical details |url=http://www.depron.co.uk/technical.htm |website=Depron foam |access-date=17 June 2020}}</ref>