Cast polyurethanes Tensile properties

Polyurethane elastomers are known for their high elongation, tensile strength and modulus properties. The combination of these properties provides toughness and durability in fabricated parts. Cast elastomers extended with butanediol can maintain these tensile properties when the use temperature is about 80 C. When these elastomers are subjected to higher temperatures, reduction in the tensile properties are observed due to the weakening of physical bonds in the elastomer. 

The tensile properties at room temperature and at intervals up to 240°C of the two series of polyurethane elastomers studied are given in Table 3.27 (block ratio 1 2 1 and BDO chain-extended) and in Table 3.28 (block ratio 1 3 2 and BDO/CHDM chain-extended). In both these series the percentage of free isocyanate calculated to be present in the elastomer on first casting is varied from 0 to 50% in 5% steps. 

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