Rheological behavior, internal stress and structural changes of ultra-high-filled wood-flour/high-density polyethylene composite in shear flow field

摘要

Wood plastic composite (WPC) is a green material with an excellent performance, environmental protection and recyclability, and potential in the field of green construction materials. A rheological study of WPC provides a key theoretical basis for mold design, equipment upgrade, production efficiency and quality improvement. In this study, an innovative approach was proposed to analyze the characters of a wood-flour/high-density polyethylene composite with an ultra-high wood-flour content (70 wt%-90 wt%, UWPC) in a shear flow field, including (1) a redesigned shear rheometer that can seal heat and (2) an analysis of the interactions between components in the UWPC by decomposing and calculating the stress during the rheological process. The stress that was generated by the UWPC melt during shearing originated mainly from wood particles and weak interfacial friction, whereas the stress that was generated by the polymer matrix could be ignored. Therefore, the polymer matrix served only to connect the wood particles and transfer stresses. Maleic-anhydride-grafted polyethylene (MAPE) enhanced the UWPC melt system interface, made the system structure more uniform and increased its fluidity. The enhancement effect of MAPE on the weak interface of UWPC melt was calculated quantitatively by calculating and analyzing the weak interfacial friction stress. The MAPE strengthening rate for the weak interface was 72.3%, 81.1% and 91.9% at 130 °C, 150°C and 170 °C, respectively. These findings can be applied to improve WPC processing and equipment manufacture.