Comparison between Material Parameters of Polyethylene Grades and the Test Performance Behaviour of Packaging for the Transport of Dangerous Goods

Abstract

For the characterization and the comparison of polyethylene grades used for the manufacture of packaging and intermediate bulk container, the following parameters are required: melt flow rate (MFR), density (D), low‐temperature notched impact strength, full notch creep test (FNCT) and increase of MFR by molecular degradation (resistance to oxidative degradation). The relationship between these material parameters determined on the basis of specimens prepared from compression‐moulded sheets of polyethylene grades and the test behaviour of packaging has been investigated in several tests. The environmental stress crack resistance determined by FNCT represents the impacts from the stacking tests performed with standard liquid wetting solution (without pre‐storage) and with normal butyl‐acetate‐saturated wetting solution (pre‐storage with normal butyl acetate). Resistance to molecular degradation by the determination of MFR increase is related to the impacts in drop tests and stacking tests performed after pre‐storage for 21 days with standard liquid 55% nitric acid at 40°C. The low‐temperature impact strength is directly comparable with the impacts in drop tests at −18°C performed without pre‐storage and after pre‐storage with 55% nitric acid. A partly good relationship was found between the test results and the material parameters. Conditioning the design types with 55% nitric acid for 21 days causes an increase in the marginal drop heights of the design types in drop tests at −18°C when compared with design types without pre‐storage. Post‐cross‐linking of the grades increases stiffness because of the acidic influence. Copyright © 2011 John Wiley & Sons, Ltd.