丁腈橡胶应力加速老化行为的研究

以丁腈橡胶为例,采用高温加速老化法,以拉伸断裂伸长率作为贮存寿命指标,通过Arrhenius方程对丁腈橡胶贮存寿命的推算,研究了不同应力作用下丁腈橡胶的老化行为,并初步探讨了应力作用下丁腈橡胶的老化机理。结果表明,应力作用对丁腈橡胶的老化行为有较大影响,当丁腈橡胶不承受任何应力作用时,采用Arrhenius方程推算其在常温下的贮存寿命超过19 a;受弯曲应力作用时,其贮存寿命降低了50%;在拉伸应力和弯曲应力同时作用时,其贮存寿命小于2 a。原因是在应力作用下丁腈橡胶的分子链发生取向变形,键长和键角发生改变并受到约束,分子链的断裂活化能降低、老化进程加快,寿命缩短。

Study of Stress Accelerated Aging Behavior of Sulfured Nitrile-butadiene Rubber

The storage life of nitrile-butadiene rubber （NBR） was calculated according to Arrhenius equation by using high temperature accelerated aging method and the criterion of elongation. The aging behavior of NBR under different stress was studied and the aging mechanism was discussed. The results showed that stress has important impact on aging behavior of NBR; when there is no stress, NBR＇ s storage life is over 19 years according to Arrhenius equation; its storage life reduces 50% under bending stress; its storage life is less than 2 years under tensile-bending stress. This is because stress will induce the orientation and deformation of NBR molecular chain, and change and restrain its bond lengths and bond angles, which also reduce the breaking activation energy of the molecular chain, accelerate the aging process, and shorten the storage life or the service life of NBR.