2016 Volume 89 Issue 10 Pages 295-301
Influence of high-pressure hydrogen exposure on rubber materials was analyzed using typical rubber models of vulcanized acrylonitrile butadiene rubber(NBR); unfilled(NBR-NF), filled with carbon black(NBR-CB)or silica(NBR-SC). Hydrogen penetrated in rubber affects volume change larger in the order of NBR-CB<NBR-SC<NBR-NF. The late hydrogen elimination in NBR-CB was explained by hydrogen adsorption on carbon black. Deterioration and recovery of elastic modulus is not due to the restraint of rubber molecular mobility but the volume expansion. Cross-linkage was not affected by the repetition of hydrogen exposure. Infrared spectroscope(IR)and solid state NMR showed no chemical structural change such as hydrogenation or chain scissions. Pulsed NMR data suggested that the change of relaxation time(T2S)ratio observed only in NBR-SC was caused by detachment or destruction of filler-gel interface or between silica aggregations. In NBR-CB, the bound rubber structure may have stronger interaction to cause no damage of fatigue by the exposure-repetition. Solid state NMR analysis for states of hydrogen penetrated in rubber revealed the existence of hydrogen in two different states; one adsorbed on rubber matrix, the other free hydrogen having no interaction with rubber matrix, which affects the volume expansion and causes deterioration.
