A Study On Rheological Behavior Of Polypropylene/Carbon-based Filler Composites

Polypropylene/carbon filler composites recently received extensive attention andresearch because of its such advantage as low density，being precessed easily. And extensilybeing used as the conductive，dielectric and friction materials. Its rheological behaviordirectly reflects both its internal structure and end-use properties.The steady state and dynamic rheological behavior and morpology ofPolypropylene/carbon filler composites contains on granular carbon black, carbon fiber andflake acicular graphite were systematically researched:Morpology of carbon fillers influence intensively steady and dynamic rheologicalbehaviors of these composites. The nonlinear flow degree of PP/CB composite is strongerthan that of PP/GP or PP/CF composite.When filler content increases, Payne effect enhances, the nonlinear flow degreeincreases, modulus values of the terminal region increases, and even terminal platform areaemerges. Payne effect in PP/CB composte more apparent, which may be that CB possessesmore activity sites which is in favor of large molecular adhesion.At the same time, When filler size changes, the rheological behaviors of thesecomposites alter significantly. Thickening and enhancement effect of small fillers incomposites are better cleanly than those of large fillers. Calculation based on percolationtheory, the percolation value of graphite with particle size of500mesh filled polypropylenecomposite is13.8%, while graphite with particle size1500mesh filled polypropylenecomposites17.2%. SEM images confirm that GP fillers are dispersed better in thesecomposites than the others. Apparently, the dispersion of small GP fillers is better than largeGP fillers in composites, which partially explains the fact that small GP filler/PP compositeholds larger percolation value and smaller critical concentration (responding to that terminalplateau region of dynamic rheological behaviors occur) compared to large GP filler/PP composite.