Abiotic degradation of recycled polymer/wood composites exposed to outdoor applications

Abstract

Wood-plastic composites (WPCs) have received increasing attention during the last decades, because of many advantages related to their use. Some of their main applications are represented by outdoor furnishing and decking; therefore, it is important to assess their behavior under Ultra Violet (UV) exposure. In this work, polypropylene/wood flour composites were prepared and their resistance to photo-oxidation investigated. The composites were prepared by extrusion and injection molding, and were subjected to mechanical and rheological tests, chemical analysis and colorimetric measurements. The results showed that the composites retained a higher fraction of the original mechanical properties after natural weathering. The study showed that for natural weathering, longer exposure time increased the degree of color change (and lightness). Weathering WPC exhibited decreased in mechanical properties when compared to no weathering WPCs respectively. From this study, relationships between chemical and color changes that occurred during exterior weathering of composites were too established. Climatic conditions directly affect the characteristics of all composites, thus indicating a significant photo-oxidation of the samples with a longer time of exposure to weathering.