Tensile Strength of Polyurethane and other Elastomeric Block Copolymers

The discussion in this paper has been focused on the strength of Polyurethane elastomers, data on other materials being presented for comparison and to illustrate factors that affect strength. Although the literature on Polyurethane elastomers is voluminous, only in recent years has it been widely recognized that plastic domains exist in most polyurethane formulations of technological importance. Evidence for domain formation and aspects of domain morphology are discussed in recent reviews. The morphology of domains in segmented polyurethane elastomers is more complex than of those in triblock elastomers and has not been studied extensively, although progress is being made, indicated by the discussions in recent publications and references cited therein. In view of the complexities of fracture and the limited information on the morphology and time-dependent mechanical properties of polyurethane elastomers, only general relations between strength and chemical structure have thus far been established. On the other hand, useful correlations can be established by considering the type, size, and concentration of the hard segments and whether strain-induced crystallization is a dominant factor.