New developments in on-line rheometry with melt return

The system design of ''melt return rheometers'' (MR) is more complex than that of rheometers discharging the melt (MD) after measurement. Consequently only single-pass capillary or slit die solutions have been used in MR rheometry so far, compared to the twin die configurations that have been frequently used in MD rheometry. A new MR-rheometer concept will be presented, which can be fitted with a single capillary, a twin capillary or a wedge die configuration. Experimental results from different polyolefin samples will be presented, comparing the influence of the die geometry especially in regard to multiple point measurements and the correlation to differences in molecular structure. Also, the real-time behavior of MR rheometers will be analyzed.