ABSTRACT

The thermo-oxidative stress relaxation in carbon-filled styrene-butadiene rubber is investigated using a two-step strategy consisting in homogeneous aging identification followed by heterogeneous aging prediction. Experimental observations of the chemical relaxation effects on the permanent deformation and on the equilibrium stiffness are reported on flat samples, containing various amounts of carbon-black fillers and aged at various temperatures and exposure times. The thermally activated degradation, implying scission-reformation mechanisms of links at a constant stretch at high temperature, is modelled from network decomposition under homogeneous aging conditions. An equivalent aging time, using the consumed oxygen across the thickness of bulk structures, is then introduced into the network alteration kinetics in order to predict the diffusion-limited oxidation effects on a bulk sample. Thanks to the model, the macroscopic chemical relaxation response and the heterogeneous damage patterns are discussed in connection to aging conditions and carbon-black filler content.

摘要

使用两步策略研究碳填充丁苯橡胶中的热氧化应力松弛，该策略包括均相老化识别，然后是非均相老化预测。化学弛豫对永久变形和平衡刚度的影响的实验观察报告在扁平样品上，包含不同数量的炭黑填料并在不同温度和暴露时间下老化。热激活退化，暗示链接在高温下恒定拉伸的断裂-重整机制，是从均质老化条件下的网络分解建模的。等效的老化时间，使用整个结构厚度消耗的氧气，然后将 引入网络改变动力学以预测对大量样品的扩散限制氧化效应。借助该模型，可以结合老化条件和炭黑填料含量讨论宏观化学弛豫响应和异质损伤模式。