NMR relaxation and NMR imaging of elastomers in the course of thermal aging

A complex aging regime occurs in the course of thermal aging of elastomers. Depending on the type and the content of the rubber filler materials, temp erature, chemical environment (normally air), and time, a different aging p rocess can be observed also by nuclear magnetic resonance (NMR) [1-6]. The methods used are the common spin-echo H-1-NMR, including variable echo time s and parameter-selective NMR-H-1-imaging (material properties imaging). Th e decay of the echo-magnetization is discussed on the basis of a single-cha in model with a distribution of dipolar interactions. This model is based o n the influence of a very fast, but anisotropic, local motion, as well as l arger and slower motions, which are able to diminish the residual dipolar i nteraction. Carbon-black-filled natural rubber, as well as silica and carbo n-black-filled E-SBR (emulsion-polymerized styrene butadiene rubber) and S- SBR (solution-polymerized SBR) are the systems under investigation, with th e results showing some characteristic features of the course of aging obser vable by NMR.