Correlation Between Material Parameters of High Density Polyethylene Grades and the Test Performance Behaviour of Packagings

For the characterization and comparison of polyethylene grades used for the manufacture of packagings and IBCs the following parameters are required: melt flow rate (MFR), density (D), low temperature notched impact strength (NIS), Full Notch Creep Test (FNCT) and increase of MFR by molecular degradation (Ox). The correlation of these material parameters determined on the basis of specimens prepared from compression moulded sheets of polyethylene grades and the test performance behaviour of packagings has been investigated with several tests.
The environmental stress crack resistance determined by Full Notch Creep Test (FNCT) represents the impacts at the stacking test at 40 °C performed with standard liquid wetting solution (without pre-storage) and with normal butyl acetate‑saturated wetting solution (pre-storage with normal butyl acetate). The molecular degradation by the determination of MFR increase represents the impacts at the drop test and stacking test performed after pre-storage (21 and 42 days at 40 °C) with standard liquid 55% nitric acid.
The low temperature impact strength represents the impacts at the drop test at ‑18 °C performed without pre-storage and after pre-storage with standard liquid 55% nitric acid.
A good correlation was found between the test results of the performance tests and the material parameters.