ABSTRACT
Polyurethanes are high-polymeric materials having —NHCOO— groups in the backbone of the polymer. This class of materials is not just the repetition of —NHCOO— groups as in polyethylene or polyvinyl chloride. The groups are present in the polymer as a result of reaction of an isocyanate (—NCO—) group at the ends of the monomers (OCN—R—NCO) with hydroxy (—OH—) groups present at the ends of other monomers (HO—R’—OH). The polyaddition reaction with diisocyanate was discovered by O. Bayer in the 1930s. Applications of the polyurethanes became apparent in the 1940s. This class of materials has become very important among the polymers because of the materials’ superior tear strength and abrasion resistance among other properties and their use is steadily increasing. The total sale of polyurethane materials in the United States was 2333 million pounds in 1986, an increase of 0.65% from 1985 [1]. The global demand outlook was 9435 million pounds, which will grow to 13,051 million pounds in 1990, an estimated increase of about 7% for the decade [2].
