Liquid vs. Solid Polyurethane Trimerization Catalysts: A Performance, Handling, and Application Comparison Abstract: Polyurethane (PUR) and polyisocyanurate (PIR) foams are integral materials in a wide range of applications, from insulation and automotive components to furniture and adhesives. The trimerization of isocyanates, leading to the formation of isocyanurate rings, is a crucial reaction in the production...