2018 年 91 巻 8 号 p. 301-308
The inhomogeneity in vulcanized isoprene rubber (IR) was examined by 1H pulsed NMR. The transverse relaxations were measured by the solid echo method and the Hahn echo method. The spin-spin relaxation time of the network component (T2HS) and the fraction (FHS) were measured by Hahn echo method. FHS/T2HS showed good linear correlation with the stress at 100% strain (S100) except for specimens in which the immobilized components were detected by solid echo method. The power law between the extension ratio at break (λB) and S100 was existed for the specimens varied sulfur content (S-series). The log λB vs. log S100 (or log FHS/T2HS) mapping, using the relation for S-series as a reference, identified the specimens deteriorated by thermal oxidation. The plot of FHS and 1/T2HS was also effective for judging deterioration. Virtual λB (λB*) expected from 1/T2HS was calculated from the relationship between λB and 1/T2HS for S-series. Virtual FHS (FHS*) was similarly calculated from 1/T2HS. Good correlation was found between λB /λB* and FHS/FHS*. Evaluation of States and prediction of fracture characteristics were shown to be possible by analysis of inhomogeneity using NMR.
