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.