Prediction of Polyethylene Molecular Weight and Molecular Weight Distribution Using Capillary Rheometer

摘要

Polyethylene is characterized by molecular weight (MW), molecular weight distribution (MWD), and density. Melt index (MI2) is measured in the quality control (QC) lab and is used as an indication of resin MW. Melt flow ratio (MFR or MI_(20)/MI2) is a calculated QC lab number, which is used as an indication of MWD. Density is a measure of crystallinity. This article shows that a capillary rheometer can provide a fast and reliable method on a production line to control MW and MWD by predicting MI2 and MI_(20) for a resin within specific ranges of density, melt index and equipment/catalysts.