Enhancing mechanical performance of polypropylene bio-based composites using chemically treated date palm filler

Utilizing agro-residues as organic fillers instead of wood is considered a sustainable option for preserving forestry. Recently, we successfully developed a new chemical treatment method to extract rich cellulosic microfibers from agro-residues of date palm trees. The treated fibers exhibited an improved performance, thus demonstrating the prominent potency of the new method. For further confirmation, in this study, we have applied the technique to treat raw microfibers and examine their performance as reinforcing elements in both virgin polypropylene (PP) and recycled post-consumer polypropylene (rPP). The chemically treated fibers were initially pulverized to a powder form using a ball milling machine and then blended with PP or rPP to make bio-composites. Specimens were fabricated at melt state using a single-screw extruder followed by compression molding. Then, a series of mechanical and physical tests were conducted on the specimens following ASTM standards. Results revealed that incorporating treated fillers into either PP or rPP has enhanced the mechanical properties of the bio-composite compared to the ones with untreated filler. Owing to the treatment, the rise in tensile strength of recycled polymer-based bio-composites was higher than that of virgin polymer-based bio-composites where treated fillers acted effectively as a nucleation agent to rPP. Additionally, a pronounced drop in water absorption and boost in crystallinity of both bio-composites were attained. However, thermal degradation was not dramatically altered. Therefore, this study showed that reinforcing rPP with treated date palm filler to make bio-composites is a reliable route for designing products across a wide range of industries.