English Abstract

Recent Low-field Time-domain NMR Spectroscopy and its Application on Analysis of Rubber Structural Change

Yuichi Aoyagi
NOK Corporation, Fujisawa-shi, Kanagawa-ken, Japan
Nippon Gomu Kyokaishi,(2021),94(11),365-371 General Review in Japanese

The NMR methods with the ILT analysis method is enable to describe precisely the structural changes occurring in the rubber network and with respect to chain mobility. With the help of this method, it was possible to quantify structural changes with crosslinking or aging. It is possible to be divide into 3 category of the shares such as physical/chemical cross-links, free chain ends and free chain fragments. In practice, sealing materials are subject to various aging processes as a function of ambient factors, for example, temperature and oxygen, frequently manifested in stress relaxation impacted critically with respect to the long-term functioning of the seal. In order to understanding it, further development of innovative characterization methods called low-field time-domain NMR spectroscopy with inverse Laplace transformation (ILT) was done. All the aforementioned material parameters were found to have a significant impact on the aging-related rubber structural change. The new characterization methods allow for a much more precise description, and thus a markedly better understanding, of aging process the stress relaxation mechanism among elastomers.

Keywords: Stress Relaxation, Aging, Seals, NMR, Inverse Laplace Transformation, EPDM