Polyurethanes and Polyisocyanurates

The reaction of an isocyanate and an alcohol results in the formation of a urethane. 

By the same reaction polyhydroxy materials will react with polyisocyanates to yield polyurethanes. For example, the reaction between 1,4-butanediol and hexamethylenedi-isocyanate is shown below  

This particular polymer is a fibre-forming material (Perlon U). Although in many respects this reaction resembles the formation of polyesters and polyamides it is not a condensation reaction but involves a transfer of hydrogen atoms and thus may be considered as an example of rearrangement polymerisation. 

Although the first polyurethanes were similar to that shown above, several polymers currently used contain many linkages in addition to the urethane group. Because of this the term polyurethane is now generally extended to cover all the complex reaction products of isocyanates and polyhydroxy compounds (the latter frequently known in this context as polyols). 

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Table 27.4 Typical applications of cellular rigid polyurethanes and polyisocyanurates...

The bulk of the ngid polyurethane and polyisocyanurate foam is used in insulation. See also Insulation (Thermal) More than half (60%) of the rigid foam consumed in 1994 was in the form of board or laminate die remainder was used in pour-in-place and spray foam applications. 

This book series presents in-depth reports on the most important new developments in urethane technology. Volumes 2-5 contain papers written only by Japanese specialists. A number of these papers concern rigid and flexible foams. Polyurethanes and polyisocyanurates are widely used in Japan. The papers cover recent developments in chemistry, processing, properties and applications. 

AX-106 Polyurethane and Polyisocyanurate Foam Insulation (Sweets Brochure). 

AX-119 Guide for the Safe Handling And Use of Polyurethane and Polyisocyanurate Foam Systems (U-118). 

Covers both polyurethane and polyisocyanurate foam, board or block, for use from -55 to 70 C (-65 to 160 F). Application is primarily for sandwich construction. 

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