Investigating the influence of the aging process on the rheological and mechanical properties of composites based on PBS matrix and enzymatically treated date palm fibers

Abstract

Over the past few decades, biodegradable polymers based on natural fibers, such as date palm fibers, have become increasingly popular as an alternative to traditional composites using inorganic fillers. These composites' properties determine their application in various fields; however, when exposed to ultraviolet (UV) rays in outdoor environments, their structure may change, leading to a decrease in their overall properties. Therefore, understanding the long-term behavior of composites following UV aging is of great importance. The aim of this study was to investigate the effect of UV irradiation on the performance of poly (butylene succinate) (PBS) biocomposites reinforced with different mass content of raw date palm fibers ( Phoenix dactylifera L.). The impact of enzymatically treated fibers, using a combination of pectinase and xylanase enzymes, on the properties of the biocomposites after being exposed to an accelerated aging process was also highlighted. All of the specimens were sampled after 100 h and 700 h of accelerated aging for laboratory characterizations. Their mechanical properties were determined by tensile tests. Rheological analyses were conducted by multi-wave tests and revealed two main phenomena resulting from UV aging; molecular chain scission and crosslinking. Tensile tests showed that the addition of raw fibers to the reference matrix resulted in a better resistance of the mechanical properties to the accelerated aging process. It was also found that the rigidity of the composites based on enzymatically modified fibers was approximately 37% higher than those loaded with raw fibers, at the same charge rate (20%) and after the same aging period (700 h).