English Abstract

Prediction of Local Tensile Properties of Thermally Oxidized Thick Rubber by Pulsed NMR Measurements with Reduced Environmental Impact

Hitoshi IWABUKI *1
Yuya MIYAKE *2
*1:Industrial Technology Center of Okayama Prefecture, Kitaku, Okayama, Japan
*2:Kurashiki Kako Co., Ltd., Kurashiki, Okayama, Japan
Nippon Gomu Kyokaishi,(2023),96(3),65-72 Original Paper in Japanese

Prediction of tensile properties by pulsed NMR measurements is improved by swelling the sample with a deuterated solvent. However, in recent years, the use of organic solvents has been avoided from the viewpoint of safety and health risks and the environmental impact of volatile organic compounds. In this study, we investigated a method for predicting the tensile properties of rubber by pulsed NMR measurements without using a swelling solvent. Spin-spin relaxation measurements in dry state and tensile tests were performed on sliced sheets sampled from the surface and interior of thermally oxidized thick-walled rubber. As a result of multivariate analysis using NMR parameters obtained from spin-spin relaxation, it was found that the spin-spin relaxation time of network component (T2HS) and its Weibull coefficient (WHS) are effective as explanatory variables for tensile properties. Regression equations using T2HS and WHS could predict the extension ratio at break (B) and the stress at 100% strain (S100) of surface and inner layers of thermally oxidized products with high accuracy.

Keywords: Pulsed NMR, Spin-spin Relaxation Time, Weibull Coefficient, Blended Rubber, Thermal Oxidation, Extension Ratio at Break, Stress at 100% Strain, Prediction of Tensile Properties