Polymer systems, predictive aging

The lack of an unambiguous method for demonstrating predictive validity of thermal accelerated-aging methods warrants extreme caution in extrapolating to long-term behavior for polymer-adhesive systems. The usefulness of such studies is often best applied to a ranking of preferred behavior under evaluative criteria. 

The data for the plot in Figure 2 was obtained using a PDMS polymer modified with a carborane unit. A schematic of the system is given in Figure 3. For this material there is no radiation effect on an interface and the plot is linear over the entire dose range. The development of an ageing model that provided a predictive capability and high confidence is far easier in a system that displays a linear trend than on with a complex non linear relationship. 

Liu, H., Zhou, M., Zhou, Y., Wang, S., li, G., Jiang, L., Dan, Y. Aging life prediction system of polymer outdoors constructed by ANN. 1. Lifetime prediction for polycarbonate. Polym. Degrad. Stab. 1 5, 218-236 (2014)... 

Analysis of volatiles is frequently utilised in food industry to quality control food products and to determine shelf-life for various products. Some recent examples are the use of sensor arrays to differentiate milk products according to their aging times (12) and the use of solid phase microextraction-mass spectrometry-multivariate data system to predict the shelf-life of pasteurised milk (13). Volatiles emitted by plants have also been correlated to abiotic or biotic stress and the degree of damage caused by the stress (14). Similar principles should be applicable to polymeric materials i.e. the formation of certain volatiles or indicator products during degradation of the polymer is related to the changes in the polymer matrix (Fig. 1). 

---