The main objective of this research was to study the influence of an enzymatic treatment process of date palm fibers on their chemical and morphological properties as well as the physical and mechanical characteristics of composites filled with raw and treated fibers. To this end, three extraction approaches were considered (a combination of xylanase and pectinase enzymes, xylanase enzymes followed by a pectinase one and pectinase enzyme followed by xylanase). Chemical and morphological analyses were performed on raw and treated fibers. The tensile test of the manufactured composites was achieved, using extrusion and injection molding process. These composites were also subjected to water absorption tests. The results showed that non-cellulosic components decreased after enzymatic treatments while the cellulose content increased significantly. The scanning electron microscope morphological analyses showed that the extraction with the combination of these enzymes is very effective as a fibrillation phenomenon. Composites with high rigidity were observed in the case of enzymatically treated fibers. These composites reveal a better moisture resistance compared to the untreated fibers.

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).

The rheological properties of biocomposites can change depending on the polymer, fiber type, fiber size and processing conditions. In this work, biodegradable PBS composites filled with raw and enzymatically treated date palm fibers were processed using an internal mixer. The influence of the processing conditions, namely filler concentration, rotor of the mixer rotational speed, as well as the type of the enzymatic fiber treatment on PBS (Poly Butylene Succinate)/date palm fiber composites were studied by measuring the torque and the temperature in real time during melt processing. A rheological analysis was also carried out by performing time and multi-wave-frequency sweeps. It was found that the stabilization torque increased with increasing fiber loading and rotor rotational speed, indicating a higher viscosity. An enhancement of the melting process occurred with modified fibers, which was explained by the decrease in the fiber diameter, denoting cellulose micro-fibrils separation by enzymes action. These composites were characterized by a better thermal resistance and mechanical stiffness compared to those based on raw fibers at the same loading rate.

The use of natural fiber-reinforced polymer materials has become increasingly common in various applications. However, the performance and durability of these composites in outdoor applications are not fully understood. Therefore, the objective of this study is to investigate the impact of an artificial ultraviolet radiation on the degradation behavior of composites based on a Poly Butylene Succinate (PBS) matrix. The reinforcement materials used in this research were the trunk and palm fibers obtained from date palm trees. Specifically, the effect of modifying the fiber surface with an enzymatic treatment on the interfacial adhesion fiber/matrix as well as on the rate of deterioration of the resulted composites, under accelerated aging, was assessed. Changes in the composite’s thermal stability, surface morphology and mechanical properties were determined after aging. A sharp transition in the behavior of the PBS matrix was observed after UV exposure, shifting from slight ductility following 100 h to brittleness after 700 h. The aging process resulted in a decrease in the thermal stability of all composites. However, the composites containing treated fibers exhibited better thermal stability compared to those with untreated fibers. Additionally, the use of enzyme-treated fibers in the composites promoted greater stability in the mechanical properties even after aging. The reinforcement of the composites with palm fibers yielded better interfacial adhesion compared to the use of trunk fibers, and resulted in better retention in the tensile strength property after aging. The enzymatic treatment facilitated stronger physical attachment between the fibers and the matrix, preventing any fiber or interface degradation.