Abstract: By taking advantage of the excellent multi-functions, including pulverization, dispersion, mixing and stress reaction of the pan-mill equipment and the good compatibilizing effects of the compatibilizer PP-g-MAH, the highly filled polypropylene (PP) wood-plastic composite with 80%(mass) wood flour (WF) having good comprehensive performance was prepared. The effects of pan-milling, compatibilizer and compounding strategy on the particle size distribution, mechanical performance and morphology structure of the PP/WF wood-plastic composite system were investigated. The particle size of the PP/WF composite at different milling cycles presented double-peak distribution. A proper increase in milling cycle was beneficial to further decrease in PP particle size and uniform dispersion of wood flour. With increasing milling cycle, the tensile and flexural properties of the PP/WF composite increased first and then decreased, but the notched impact strength constantly decreased slightly. The introduction of PP-g-MAH and the increase in its content would contribute to remarkable improvement in the mechanical performance of the PP/WF composite and the best flexural modulus occurred at 5% PP-g-MAH. In addition, the mechanical properties of the PP/WF composite prepared by pan-milling were better than those of the material prepared by the conventional mastication compounding method. The change in mechanical properties mentioned above was attributed to improved dispersion of wood flour in PP/WF highly filled composite system caused by pan-milling and remarkable enhancement in compatibility of system caused by the incorporated PP-g-MAH. The involved compatibilizing mechanism of PP-g-MAH was believed to be the mechano-chemical grafting esterification reaction of PP-g-MAH with the hydroxyl groups at the surface of wood flour under the strong shear force field of pan-milling.

Key words: solid state shear milling, polypropylene, mixing, composite, size distribution, compatibilizing effect

摘要： 利用磨盘形力化学反应器优异的粉碎、分散、混合和力化学反应的多重功能以及增容剂PP-g-MAH的良好增容作用制备了综合性能优良的聚丙烯(PP)/木粉(WF, 80%,质量分数)高填充木塑复合材料,研究了磨盘碾磨、增容剂以及复合方式对PP/WF木塑复合体系的粒径分布、力学性能和形貌结构等的影响.结果表明,不同碾磨次数的PP/WF复合粉体的粒径呈双峰分布,适当增加碾磨次数有利于PP粒径的降低及木粉的均匀分散.随碾磨次数的增加,PP/WF复合材料的拉伸和弯曲性能先增加后下降,但缺口冲击强度一直呈小幅下降趋势.PP-g-MAH的引入及其含量增加均有利于PP/WF复合材料力学性能的大幅改善,其中弯曲模量在增容剂含量为5%(质量分数)时最佳.此外,磨盘碾磨制备的PP/WF复合材料的力学性能优于常规密炼复合法.上述力学性能变化归因于磨盘碾磨改善了PP/WF高填充复合体系中木粉的分散性以及加入的PP-g-MAH显著改善了体系的相容性,其中PP-g-MAH的增容机理为磨盘碾磨剪切力场作用下PP-g-MAH与木粉表面羟基发生了力化学酯化接枝反应.

关键词: 固相剪切碾磨, 聚丙烯, 混合, 复合材料, 粒度分布, 增容作用