Heat Resistant Isocyanate Based Foams for Structural Applications

This paper describes unique types of isotropic urethane-isocyanurate and urethane-urea isocyanurate foams based on a combination of an aromatic polyester polyol and an amine-containing tetrol as the only polyols with a low functionality polymeric isocyanate. The effects of isocyanate index, foam density, and curing temperature, as well as the mode of foaming (free-rise versus moulded) on the foam properties, were studied. The foam isotropy index, defined as the ratio of compressive strength parallel and perpendicular to the foam rise, was 1.0 (ideal). The normalized compressive strength (parallel and perpendicular) was 13 kPa/kgm ^-3 . The moulded PIR foams exhibited excellent durability in the drop weight impact test and a high degree of property retention at 121°C.