ABSTRACT
For economic reasons, however, it is not possible to wait years for the results of outdoor weathering. Thus there is a need for accelerated weathering in the laboratory. This is intended to identify and measure the same changes in the properties of polymeric materials that would occur under real conditions during the normal service life of these materials. This is a very high goal to aim at, since accelerated time testing generally poses the danger of initiating degradation processes other than those occurring in general practice, apart from the desired acceleration of the aging processes that do occur naturally; or, by the same token, changes occurring in the materials outdoors may not take place during accelerated weathering, or not to the same extent. This chapter will present various methods of outdoor weathering and explain the fundamental possibilities for acceptably accelerating weather-related aging processes, as well as which methods
Figure 1 Principal reactions and interactions.
