超高填充聚丙烯基木塑复合材料高低温性能

为了充分降低成本，增加环境友好性并获得良好的木质感，以杨木纤维和毛竹纤维为原料，通过挤出成型制备超高填充聚丙烯基木塑复合材料(UH-WPCs)。基于聚丙烯基体含量的大幅降低，对比分析了填充量和木质纤维种类对UH-WPCs高低温力学性能、高低温蠕变性能、热膨胀性能、尺寸稳定性及吸水性能的影响。结果表明，随着填充量从75wt%增加到90wt%，其线性热膨胀系数大幅降低，蠕变应变逐渐减小而在90wt%时增大；拉伸模量和弯曲模量随填充量的增加先升高而后在90wt%时下降；拉伸强度、弯曲强度和冲击强度随着填充量的增加逐渐降低；在低温?30℃时UH-WPCs的拉伸和弯曲性能较高，高温60℃时冲击韧性较好。温度、湿度及含水率变化均导致UH-WPCs尺寸变化，其中厚度方向尺寸变化率最大，其次为宽度方向，长度方向最小，表现出明显的各向异性；湿度对UH-WPCs的尺寸稳定性的影响远大于温度的作用。杨木基UH-WPCs综合性能优于毛竹基UH-WPCs，这与杨木纤维具有更大的长径比及良好的界面结合有关。UH-WPCs的研究为降低WPCs生产成本和拓宽其应用领域提供了理论依据。 

High- and low-temperature performance of ultra-highly filled polypropylene-based wood plastic composite

To reduce costs, increase environmental friendliness, and obtain a good wood feeling, ultra-highly filled polypropylene-based wood plastic composites (UH-WPCs) were successfully prepared by extrusion technology using poplar wood fiber and bamboo fiber as raw materials. Based on pronounced reduction in polypropylene matrix content, the effect of filling content and fiber species on mechanical properties and creep resistance at high and low temperatures, thermal expansion, dimensional stability, and water uptake behavior of the UH-WPCs were investigated. The results show that as the filling content increases from 75wt% to 90wt%, the linear thermal expansion coefficient of the UH-WPCs decreases drastically, creep strain decreases gradually but increases at 90wt% filling content, and the tensile and flexural moduli increase firstly and then decrease at 90wt% filling content. The tensile strength, flexural strength and impact strength decrease gradually with the increasing filling content. The UH-WPCs show higher tensile and flexural properties at ?30℃, while the impact toughness is higher at 60℃. The variation of temperature, humidity and moisture content can lead to the dimensional change of UH-WPCs. The UH-WPCs exhibite obvious anisotropy in dimensional change. The largest change in dimension was observed in the thickness direction, followed by width and length direction. The effect of humidity on the dimensional stability of UH-WPCs is more significant than that of temperature. The UH-WPCs prepared with wood fiber show better comprehensive properties than that with bamboo fiber, which is attributed to the larger aspect ratio of wood fiber and better interface adhesion of wood fiber-filled UH-WPCs. The research of UH-WPCs provides a theoretical basis for reducing cost of WPCs and broadening its application scenarios.