Polyisocyanurate

The generalised chemical structure of polyisocyanurate showing the isocyanurate group. The polyols are abbreviated as R-groups.

Polyisocyanurate (/ˌpɒlɪˌaɪsoʊsaɪˈænjʊəreɪt/), also referred to as PIR, polyol, or ISO, is a thermoset plastic[1] typically produced as a foam and used as rigid thermal insulation. The starting materials are similar to those used in polyurethane (PUR) except that the proportion of methylene diphenyl diisocyanate (MDI) is higher and a polyester-derived polyol is used in the reaction instead of a polyether polyol. The resulting chemical structure is significantly different, with the isocyanate groups on the MDI trimerising to form isocyanurate groups which the polyols link together, giving a complex polymeric structure.[2]

  1. ^ Building Science Corporation (January 2007). "Guide to Insulating Sheathing" (PDF). p. 6.
  2. ^ Merillas B, Martín-de León J, Villafañe F, Rodríguez-Pérez MÁ (April 2022). "Optical Properties of Polyisocyanurate-Polyurethane Aerogels: Study of the Scattering Mechanisms". Nanomaterials. 12 (9): 1522. doi:10.3390/nano12091522. PMC 9100237. PMID 35564231.