A fundamental problem of advanced airplane com-posite Systems is the lack of understanding of the aging processand how it affects the material properties associated withdegradation. The concept of Equivalent Property Time (EPT) wasestablished and can be used to understand degradation of polymersand composites in a uniform manner, both for isothermal anddynamic elevated temperature exposures. In this work,bismaleimide neat resin and composite degradation was analyzedwith isothermal and dynamic thermogravimetric analysis adaptinga descriptive time-temperature concept originally developed forthe curing of thermosets. The concept, defined as EPT, describedthe experimental data accurately for the experimental conditionstested. Thus, this methodology was demonstrated to be a usefultool in designing aging experiments and assessing the lifetime ofcomposite systems. An extension of this concept was developed toinclude Equivalent Cycle Time (ECT), which involves the effectsof cycling-heating, cooling, and holding, which can be used tounderstand degradation aging phenomena from repeated exposure.Collectively, this work focused on providing an understanding ofcycling phenomena for polymers and composites as they relate toenvironmental influences and their accelerated aging behavior.
展开▼
