Accelerated UV Weathering of Polymeric Systems – Recent Innovations and New Perspectives

By Joannie W. Chin, Tinh Nguyen, Xiaohong Gu, Eric Byrd, Jonathan Martin

Polymeric materials, used in an outdoor environment are subjected to a wide vari­ety of environmental factors, including solar ultraviolet (UV) radiation, tempera­ture, and moisture, in a process known as weathering. Understanding the factors that govern the weathering performance of commercial polymeric materials has great practical importance, as does the ability to relate laboratory performance of a polymeric system to its performance in the field.

At present, the full potential of these materials is inhibited by the absence of a methodology for accurately predict­ing their service life during exposure in their end-use environments. A reliability- based methodology utilizing total effective dosage as an exposure metric has been proposed as an alternative to the conventional methodology for carrying out labora­tory and outdoor weathering studies.

The use of this proposed methodology involves not only a shift in paradigm but also in the way that laboratory and outdoor weathering experiments are carried out. The concepts of reciprocity and additivity, which were first introduced by the photographic community and then studied by the med­ical and biological communities, are also proposed as models for synthetic polymeric systems.

Synthetic and natural polymeric materials play an increasingly important role in today’s society, and the versatility of these materials has been demon­strated through the breadth of their applications in almost every sector of the economy. The full potential of these materials is inhibited by the ab­sence of a methodology for accurately predicting their service life during exposure in their end-use environments, This deficiency has been noted by in­dustry and emphasized in a number of recent National Research Council (NRC) reports.