Elongational viscosity in quality control, 2007 European PLACE Conference

Please Note: This document will be available in PDF format in the "My Electronic Documents" link on the home page once your order has been completed. Please make sure you have the latest version of Acrobat Reader. Click on the Acrobat Reader icon to check for the latest version, it’s FREE. To print a hardcopy of a PDF file correctly you must have a postscript printer. If you are not sure if your printer is a postscript printer please refer to your owner’s manual.

Several shear and elongational flow experiments are currently used in quality control of resins for high-speed extrusion coating. Beyond MFR and capillary rheology, also data from the dynamic shear experiment such as G’ or ç0 are collected and they show excellent correlation with processing stability in terms of maximum draw down and neck-in. However, data of any shear experiment are only of limited value when it comes to comparing different material classes, such as polyethylenes and polypropylenes. For latter purpose, data from elongational devices are preferred. They show better inter-material comparability since they are more close to the fast elongational flow observed in high-speed extrusion coating. For some time, the device of choice for assessing polymers’ elongational flow properties has been the Rheotens tester. It offers great reproducibility and excellent correlation with the performance of resins in extrusion coating. Its drawback is the inter-laboratory comparability. With a new extensional stressing device, called SER and outlined in the presentation, it is now possible to measure extensional rheology with high throughput in a very comparable and standardized way. Present paper shows first results on correlations of the results from the SER extensional rheometer with process stability in extrusion coating, based on PE and PP with praticular view on Daploy™ HMS-PP grades.