红外光谱研究丁基橡胶老化机理及寿命预测

对丁基橡胶进行室内加速热氧老化实验,同时采用FTIR实时追踪丁基橡胶在老化过程中化学结构的演变,并进行二维相关分析.结果显示老化过程中C-H和C-C氧化形成自由基的速率较慢,为确定热氧老化反应速率的关键步骤,随后进行的热氧老化反应速率很快,最终氧化降解形成醛,酮,酯等老化产物.在充分理解丁基橡胶热氧老化机理的基础上,建立了丁基橡胶热氧老化的基元方程,按照老化过程中各基元反应的质量作用定律,建立了材料老化的氧化动力学模型.采用Matlab编程,计算得到丁基橡胶在常温和高温之间的老化速率比.通过红外光谱追踪老化过程中基团变化的实验数据拟合建模计算得到的曲线,发现两者的变化趋势相同,表明采用该方法预测材料老化寿命具有极好的应用前景.

Aging Mechanism and Lifetime Prediction of Butyl RubberUsing FTIR Techniques

Thermal-oxidative aging experiments on butyl rubber were conducted, and structural evolutions of the
rubber during aging were traced by real time infrared technique,and the resulting data were analysized by a 2D correlation
spectroscopy analysis. The results suggest that free radicals derived from saturated C-H and C-C bonds which
are attacked by oxygen atoms form slowly at the early stage of thermal aging. And it is a key step to determine the reaction
speed. After that, the carbonyl species are generated rapidly, which results in formation of aldehydes, ketones
and esters etc. and finally by degradation and oxidative. Based on a full understanding on the thermal-oxidative aging
mechanism of butyl rubber, we constructed elementary reaction equations and furthermore, oxidation kinetic models
according to mass action law of each elementary equation. The aging rate ratio of room temperature to high temperature
is obtained by calculation of Matlab program. By fitting the curves described from the oxidation kinetic models with
the data from FTIR tracing experimental for the aging process, it is found that both changes have the same tendency,
which promises an excellent prospect for predicting lifetime of materials.