Comparison of the resistance to oxidative degradation of polyethylene grades with the test performance behaviour of packagings for the transport of dangerous goods

The resistance to oxidative degradation by nitric acid is one of the selected properties together with the corresponding test method and tolerances for a comparison of polyethylene grades of one design type in the procedural rule on suitability proof for alternative plastic resins used for packagings and intermediate bulk containers (IBCs) for the transport of dangerous goods.
Comparison of the resistance to oxidative degradation of polyethylene grades and comparison of the times to failure in stacking tests with 55 % (70 %) nitric acid at 40 °C and of the marginal drop heights determined in drop tests at – 18°C with pre-stored packagings made of these grades led to the same evaluation of the grades. Conditioning the design types with 55 % nitric acid for 21 days at 40 °C causes an increase of the marginal drop heights of the design types in drop tests at ‑18 °C when compared with design types without pre-storage. Variations in a comparison of the design types produced of different polyethylene grades can be explained by applying additional examination methods such as FTIR spectroscopy.
Measurement of tensile strength and breaking elongation is in principle suitable for a comparison of polyethylene grades regarding resistance to oxidative degradation.