Bonding in urethane elastomers

✍ Scribed by Weisfeld, L. B. ;Little, J. R. ;Wolstenholme, W. E.

• Publisher: John Wiley and Sons
• Year: 1962
• Weight: 469 KB
• Volume: 56
• Category: Article
• ISSN: 0022-3832
• DOI: 10.1002/pol.1962.1205616417

✦ Synopsis

Abstract

Ordinary modulus–temperature physical test data at low deformations for unswollen gum elastomers has been partitioned into contributions from primary and secondary interchain linkages. The analysis is based upon the supposition that primary or covalent bonds conform to the statistical theory of rubberlike elasticity, while secondary interchain bonding adheres to Arrhenius Law. This treatment was applied to peroxide‐cured millable elastomers, diamine‐cured polyester diisocyanates, and several thermoplastic polyureaurethanes. Information resulted on the primary crosslink density, cure agent efficiency, activation energy for secondary bonding, and the relative contributions of respective bonding phenomena at various temperatures. These considerations afford a better understanding of the relationships between structure, composition and mechanical properties in polyurethane elastomers. Mechanisms are proposed relating the type of crosslink to its effect on secondary bonding, and the geometry of the spine on deviations from kinetic elastic theory at high extensions.