Techniques for the analysis of aging signatures of silica-filled siloxanes

Degradation mechanisms for complex polymer systems are often subtle and difficult to detect, yet a precise understanding of their effect on a polymer component's macroscopic performance is necessary for understanding aging behavior. Furthermore, predictions of the engineering performance of aged components are prone to large errors when the service lifetimes are much greater than the duration of laboratory aging tests, especially when multiple degradation mechanisms contribute to the overall aging. In order to avoid these errors, lifetime-performance models for components are needed that acknowledge the changes brought about by aging or damage over many size domains, from the macroscopic to the molecular level. We are studying a silica-filled siloxane foam using techniques which link aging and damage over several size domains in order to improve our material/component lifetime predictions. Parameters such as radiation-induced crosslinking, changes in motional dynamics caused by desiccation, and mechanical damage are incorporated into Finite Element Analysis codes and combined with computed tomographic data to provide "age-aware" models and predictive capability at the component level. (C) 2003 Elsevier Ltd. All rights reserved.