Evolution of the Nanostructure and Viscoelastic Properties of Nitrile Rubber upon Mechanical Rejuvenation and Physical Aging

Extending the mechanical lifetime of NBR (i.e., poly(acrylonitrile-co-butadiene)), a large-volume synthetic rubber, requires better understanding its structure–property relationships. We demonstrate that industrial-grade and uncross-linked can be mechanically rejuvenated physically aged due to an inhomogeneous distribution monomers along polymer chains. As opposed nonpolar SBR counterpart poly(styrene-co-butadiene)), experiences thermodynamic driving forces for microphase separation kinetic barriers processing like those block copolymers. Extruding at high temperature shear results in weakly microphase-separated nanostructure low relaxation time resistance flow, whereas aging leads lamellar nanodomains, more solid-like material, delayed stress relaxation. This effect rejuvenation on rheological properties has important consequences storage conditions, such as formation defect-free interfaces multilayered parts by interdiffusion.