Rheological behavior and mechanical properties of ultra-high-filled wood fiber/polypropylene composites using waste wood sawdust and recycled polypropylene as raw materials

• UH-WPCs were successfully fabricated using recycled PP and waste WF. • R-PP protected WF from damage due to the improved wettability and plasticization. • UH-WPCs exhibited more complex solid-like rheological behavior than the traditional WPCs. • This study formalizes a sustainable strategy for full-component utilization of the industrial waste and residue. The development of wood-plastic composites (WPCs) is one of the key scientific interests in recent years for recycling industrial waste and reducing environmental pollution risks. In this study, low-cost and high-strength ultra-high-filled wood fiber/polypropylene composites (UH-WPCs) were fabricated using recycled polypropylene (R-PP) as the polymer matrix and 60–85 wt% recycled wood fiber (R-WF) from the waste sawdust of phenolic resin enhanced wood products as reinforcement. The UH-WPCs possessed robust mechanical properties and better creep resistance than composites using original WF or PP due to the sufficient R-WF/R-PP interface interaction. Specifically, compared with R-WF/PP composites, the maximum increases in the tensile, flexural, and impact strength of the R-WF/R-PP composites at 80 wt% R-WF content were 94.30%, 89.66%, and 96.33%, respectively. The Burges model could well predict the solid-like rheological behavior of UH-WPCs. This study formalizes a preventive sustainable strategy for full-component utilization of the industrial waste and residue.