Abstract: Wollastonite filled PP was studied in this work. The mechanical properties and SEM morphology of PP/Wollastonite blends were determined after being extruded by a dynamic tri-screw extruder. The effect of different dynamic parameters on the mechanical properties and the section microstructure were investigated. Compared with those based on steady condition, impact strength, tension strength, elongation ratio at break, and flex strength of the samples improved remarkably under dynamic working condition，the maximum increments being 10.7 %，10.2 %，51.3 %, and 18.6 %, respectively. Under the dynamic condition of f=10 Hz and A=105μm, the dispersion of wollastonite was improved, the particle size became smaller and more uniform, as revealed by SEM analysis.

Key words: tri-screw extruder, dynamic plasticizing, wollastonite, polypropylene, mechanical property