Abstract
Melt rheology of incompatible binary polymer blends was investigated with capillary flow measurements and dynamic flow ones. Various factors which influence the rheological properties of the polymer blend system wereinvestigated to establish the evaluation of melt rheology for this system. Samples were binary polymer blends consisting of polycarbonate (PC) and linear low density polyethylene (LLDPE). Measurements were carried out under the same conditions to compare the data obtained from each rheometer. A discrepancy between two capillary rheometers was found for the steady shear flow data. The results of dynamic flow measurements of two rotational rheometers with cone plate also showed some discrepancies. However, these were smaller than those of the capillary flow measurements. There was a clear difference between the data of the cone plate instrument and those of the parallel plate one. The measured values of the parallel plate were higher than those of the cone plate over the entire range of blend compositions. Thus in PC/LLDPE blend systems, experimental conditions must be clearly stated, because rheological properties are strongly affected by blend composition, temperature, and the geometry of the test fixture.
