Characterization Of Different Filler Dispersion And Study On The Rheological Properties Of CaCO₃/LLDPE Composite

The filler dispersion has a greatly effect on the properties of filled polymer composites. Different states of filler dispersion have different effects on the rheological behavior of filled polymer composite. Under the mesoscopic scale, Evaluation system based on the scanning electron microscopy (SEM) and image analysis method is built to estimate the different states of filler dispersion under the preparation of different mixing conditions. At the same time, the rheological model of filled polymer system is used to describe the rheological properties of the CaCO3/LLDPE composite material. DSC and XRD methods are used to discuss the rheological behavior by researches about the effect of filler particles on bound of the molecular chain, the relative movement of molecular chain and the crystallization behavior. The main conclusions are made as follows:(1) Dispersion size in composite materials has a direct effect on the rheological properties of polymer melt. With the addition of filler particles, the solution of polymer molecule chain and the relative motion are reinforced as well as the apparent viscosity, and the shear thinned effect increases.(2) The effect of different filler dispersion state in composite material on the polymer melt viscosity effect exists an inflection point. When average particle surface area is greater than6.567microns in diameter, with the particle size increase, the solution of melt molecule chain will be harder, and the melt viscosity will increase; When average particle surface area is less than6.567microns in diameter, particles get into the molecular chain and hinder the relative movement between the molecular chains and lead to the disappearance of Newton platform, which make the shear thinned effect more apparent, the effect will be enhanced with the reduced particle size.(3) The content of CaCO3has a direct effect on the melt rheological properties of composite materials. When content is low (less than10%), effect on the relative movement of molecular chain and reconciliation is small because of less number of particles which can get into the molecular chain; when content is higher (above20%), particles directly affect the relative movement between the molecular chain and the reconciliation process, its rheological curve of Newton’s platform disappear and the shear thinned phenomenon is more prominent.