There has been increasing usage of polymeric materials for structural and transportation applications. Using polymeric materials in construction is relatively new and therefore information on their service life performance is limited. In order to ensure that these materials can achieve the appropriate design life, the mechanisms leading to their degradation should be studied. Professor Grace Hsuan, PhD and her doctoral student Siavash Vahidi (CAEE) are leading Drexel’s participation on a research project titled “Testing, Evaluation, and Specification for Polymeric Materials.” Drexel is a collaborator with the University of North Florida and this project is funded by the Florida Department of Transportation. Two undergraduate students, Kenneth Reyes (MEM) and Hieu Nguyen (MEM), are also helping with this project.
Sunlight is recognized as the most important factor in polymer degradation. When the sunlight radiation is absorbed by the polymer, the chemical bonds can be broken and a chain of reactions are then initiated. Eventually, these reactions will lead to polymer degradation affecting the mechanical properties and causing discoloration. To simulate the sunlight degradation in the laboratory, a weatherometer with Xenon lamp is used. With appropriate filters, the irradiance from the lamp is similar to the sunlight at noon time in Florida. In this study, test materials include high density polyethylene products used in marine environments and five types of composites products complying with American Disability Act (ADA) used in pavement. Samples from these materials are exposed to the Xenon weatherometer under specified conditions. These samples are retrieved at scheduled time intervals and tested for their material properties. The results will be analyzed to understand the degradation mechanisms in order to predict the service life of these products under the tested conditions.
Image to the right: Siavash Vahidi removing samples from weatherometer.