Looking to the future - SHT test methods for estimating long-term properties are developed and offered at SKZ
Plastics play an important role in a wide range of construction products, but reliable testing is essential, especially for applications with a long service life. The SKZ Plastics Center offers a new and more efficient method.
Specimen after successful strain hardening test. (Photo: SKZ)
Research project to characterize the stress crack resistance of polypropylene
Reliable testing is indispensable, especially for products designed for a particularly long service life. Plastics have played a major role in construction products for years. Applications include pipes, landfill liners or geotextiles. These are applications with a long service life, high stress and a cost-intensive repair effort or risk in case of failure. Therefore, reliable testing of resistance to failure is necessary for such products.
High accuracy and reproducibility
At SKZ, the Strain Hardening Test (SHT) is a method for rapid characterization of stress crack resistance. In a research project, the method has now been further developed for use with polypropylene, starting with polyethylene. By comparing the results of two comparative methods (full-notch creep test and cracked round bar test), it was possible to show that the test method can be used with high accuracy and reproducibility.
Influence of different parameters evaluated
With this project, SKZ is helping to create a basis for evaluating the stress crack resistance of polypropylene products. To this end, the influence of various parameters such as molecular structure, morphology, colorant and filler addition, and processing on the results of SHT has been specifically evaluated.
Less time required than conventional methods
"The strain hardening test provides the industry with another economically attractive tool for characterizing stress crack resistance," explains Britta Gerets, a scientist at SKZ. Especially in terms of time, the method offers an interesting alternative to the established testing methods for polypropylene.
