Effects of composition and extrusion parameters on the morphological development and rheological properties of PP/PC blends. Co-continuity investigation

摘要

The interrelation between morphological development and rheological behavior of polypropylene-polycarbonate (PP/PC) were investigated for wide range of composition of polymer blends. The blends were prepared in a twin screw extruder where the intensity and temperature of extrusion were evaluated. The morphology of blends was obtained on a scanning electron microscopy (SEM) and the rheological properties were investigated at different temperatures in the linear regime by a dynamics analyzer up to 10-2 rad/s. It was shown that the blend composition has a great influence on the rheological parameters. Thus, when the polypropylene is the matrix the dynamicmodulus and complex viscositywere in between those of the neat components. In the other case, when the polycarbonate is the matrix the rheological properties of blend are greater than the two polymers formed the blend. At 30 wt% of PC in PP matrix, a negative deviation of blend (NDB) was shown. The effect of the shear rate on the rheological properties shows that an increase of the screw speed in the extruder decreases the Newtonian viscosity and relaxation time of the blend. Complementary information on this type of blend was deduced by using co-continuity investigation. The evolution of the extraction of PC in function of time gives information on the real microstructure of the blend, that PP encapsulates PC.