Optimizing the rheological and mechanical properties of ultra-highly filled wood fiber/polyethylene composites through binary alloy matrix strategy

Abstract

Enhancing the interfacial adhesion and rheological behavior of ultra-highly filled wood-plastic composites (UH–WPCs) presents a considerable challenge. We developed a bespoke binary alloy matrix of high-density polyethylene (HDPE) and maleated polyethylene (MAPE) to fabricate UH-WPCs with 70–90 wt% filler contents. Fourier-transform infrared spectroscopy and thermogravimetric analysis validated that about 22.3 % of MAPE engaged in esterification with wood fibers (WFs) in 80 wt% loading UH-WPCs, manifesting in noteworthy plasticization as evidenced by WFs' sheet-like structures. Rheological assessments illustrated that higher MAPE proportions reduced the viscosity of both the specialized alloy and UH-WPC melts significantly. By fine-tuning the MAPE to HDPE ratio to 16:2, we achieved marked enhancements in UH-WPCs' mechanical properties and dimensional stability: tensile strength and flexural strength increased by up to 141.7 % and 151.0 %, respectively, while creep strain and equilibrium water absorption decreased by as much as 27.3 % and 36.7 %. This research lays a robust scientific foundation for the efficient processing and enhancement of UH-WPCs, highlighting its potential for substantial improvements in mechanical performance, stability, and processability.