Study On The Preparation Of Carbon Materials Filled Poly (Vinylidene Fluoride) Composites Based On Rotors With Different Geometry

Rotor structure is an important factor to affect the mixing characteristics of mixing facilities. In purpose of improving the performance of carbon materials filled polymer composites, the paper studied the effect of rotor structure and technological condition on the mixing process. Numerical simulation was conducted to characterize the mixing performance of laminated rotor and drum-type rotors with different helix angle (67.5° and 40°) by using POLYFLOW software, further discussion was taken on the melt flow pressure and shear rate distribution, as well as the deagglomeration and distribution ability of the rotors. Furthermore, carbon fiber (CF)/poly(vinylidene fluoride) (PVDF) composite and multi-walled carbon nanotubes (MWCNTs)/poly(vinylidene fluoride) (PVDF) composite were prepared with the proposed rotors. Their electrical, thermal and mechanical properties were characterized to understand the effect of mixing flow features on the micro morphology, physical and mechanical properties of the composites. The main conclusions are made as follows:(1) The strong shear effect of the laminated rotor makes it more suitable for dispersion mixing, while the higher tension flow existence in the drum-type rotor mixing process makes it more suitable for distribution mixing. Especially, the drum-type rotor with 40° helix angle possesses the best distribution mixing property.(2) The drum-type rotor possess relatively weaker shear mixing effect, which benefit longer CF residence in CF/PVDF composite, while its higher tension flow capability helps CF to get well distribution state in composite. The composite prepared by the drum-type rotor with 40° helix angle shows 435μm CF length residence, compared to that prepared by the laminated rotor, it is 257μm longer, and the tensile strength is 15MPa higher.(3) MWCNTs/PVDF composite preparation experiment shows that stronger shear effect helpls to improve the dispersion of MWCNTs in the composite. The composite prepared by the laminated rotor shows a better dispersion, which improves the formation of percolation network, leading to a volume resistivity at 106Ω·cm, comparatively, the composite prepared by the drum-type rotors shows a volume resistivity at 1014Ω·cm, due to the agglomeration of MWCNTs.