Monitoring of Rheological Indicators of LDPE, 2005 PLACE Conference

LDPE,s from high-pressure autoclave reactors for extrusion coating with Melt Flow Rates (MFR,s) from 6 to 9g/10 min., and with densities of 917-921 kg/m3, have been considered uniform commodities for a long time. However, as coating lines became faster, differences in processing performance among LDPE,s have been observed even though they met MFR and density specifications. These problems included web break and edge instabilities causing PE missing. Various LDPE,s behaved differently in the coating process due to differing rheological properties. This paper presents results of our investigation comparing several LDPE,s. Results showed significant differences in their rheological properties. These differences significantly affected performance of the LDPE,s in the extrusion coating process. A further finding was significant variation in rheological properties and resulting performance within the same grade from the same supplier.