Dwight K. Hoffman

Model System for a Urethane-Modified Isocyanurate Foam:

far back as the 1800’s [1,2]. However, it has only been recently that this has been used advantageously to prepare rigid cellular plastics having superior ignition resistance* [3,4]. The foam’s thermal stability is due to the cyclic structure and the hydrogen-free nature of the isocyanurate rings. Generally, the best isocyanurate foams are made by polymerizing polymeric methylene diphenyl isocyanate (MDI). While these foams have excellent ignition resistance, the highly crosslinked structure is brittle [5]. As a result, they have poor compressive strength and are very friable. This has been a considerable handicap for commercialization, and there has been a major effort to synthesize modified foams having a balance of properties. Some of these modifications include adding amide, imide, oxazolidone, carbodiimide or urethane linkages [5-10]. The most popular of these approaches-due to convenience, processability, and economics-has been to make urethane-modified isocyanurate foams [11,12].