Sunlight Tracking And Concentrating Accelerated Weathering Test Applied In Weatherability Evaluation And Service Life Prediction Of Polymeric Materials: A Review

Artificial accelerated aging tests, which usually expose materials to artificial light sources and simulated environment conditions, are commonly conducted to evaluate weatherability and service life of polymeric materials. However, one main limitation of these methods is that the testing protocols usually ignore a significant amount of environmental effects which may change failure mechanisms of polymers caused by natural factors, such as seasonal variations, microorganisms, ozone, airborne chemical pollutants and salt. As a result, the polymeric materials verified by the artificial aging acceleration tests quickly show degradation phenomena, including discoloration, fading, cracking, and brittle fracture after exposed to the real service environment. Besides, these degradations could make the service life of industrial equipment and products much shorter than the expected one. Alternatively, sunlight tracking concentrator testing (STCT) which accelerates aging under natural exposure has been widely used for weatherability and service life evaluation of polymeric materials. The testing method not only takes natural aging effects into account but also achieves a high aging acceleration rate. This review article aims to summarize various structures and principles of sunlight tracking concentrator (STC), correlation and acceleration of STCT, the research progress of weatherability, and the investigation of service life prediction for polymeric materials such as plastics, coatings, and solar energy conversion materials using STCT over the years. The aging behavior and mechanism of testing materials and the corresponding correlation between STCT and natural weathering are also discussed. In addition, existing problems and future development direction of STCT are prospected as well.