Preparation Of Polyvinylidene Fluoride Thermal Conductive Composite Materials

Corrosion resistant heat-exchange equipments have a wide application in industrial production and energy recycling process. The innovation of materials with strong corrosion resistance, high thermal conductivity and strong mechanical properties would benefit the development of corrosion resistant heat-exchangeheat equipments to fullfill the requirments of petroleum chemical industry.In this paper, various Polyvinylidene Fluoride (PVDF) composites were prepared. By melt mixing method, high thermal conductive composite was prepared with flake graphite and carbon fiber as filler, whose thermal conductivity reaches to 12.42 W/(m-k), tensile strength to 55MPa and impact strength to 27MPa. By solution dispersion method, carbon fiber sheet enhanced PVDF/graphite powder composite was perpared with thermal conductivity at 29W/(m·k), bending strength at 44Mpa and impact strength at 21MPa. Scanning electron microscopy was used to characterize the dispersion state of fillers in PVDF matrix, which evidence the influence of mixing process, composite formulation and surface treatment of carbon fiber on the fillers dispersion. The PVDF crystallization behavior of composite were also investigated by differential scanning calorimetry and X ray diffraction analysis, which indicate correlation to the morphology and content of fillers in composite.The main results are shown as follows:(1) Flake graphite with different platelet size were mixed to prepare flake graphite/PVDF composite. It is shown that the synergistic effect of different size flake graphtie filler induces fillers’packing compactness, which helps to decrease the interspace among the graphite platelets and benefit the formation of thermal conductive network.(2) Chaos mixing process would faciliate the fillers dispersion in PVDF matrix, which consequentially improves the interfacial bonding between fillers and polymeric matrix.(3) The introduction of flake graphite and carbon fiber improves the heterogeneous nucleation of PVDF matrix, which promote the increase of composite’s temperature of crystallization (Tc).(4) The addition of 3D braided structured carbon fiber sheets into graphite powder/PVDF composite would not only maintain the composite’s thermal conductivity level, but also promote the overall mechanical properties of the reaced composite.