Changes in the properties of ABS materials under the influence of artificial aging
12. 04. 2021
Problem
The manufacturer of refrigeration technology incorporates 4 different ABS plastic materials into its products. We researched why cracks made of ABS material occur after a period of several years in some refrigerators.
Methodology
Since most of the affected plastic parts were mounted on visible parts of the refrigerators, we hypothesized that the brittleness of the ABS material occurs due to regular cleaning of the cabinets.
From all four samples of ABS material, standard test specimens according to ISO 527-2 / 1A were made and exposed to the following conditions before performing the tensile test:
- No additional exposure before the test
- 24 h branch of test specimens in 6 most common means used for cleaning refrigeration technology
- 24 h exposure of test specimens in the 6 most common means used for cleaning refrigeration technology + prestressed state.
We decided on the exposure to cleaning agents and the prestressed bending state, because some plastic elements in the product are mounted in the prestressed state.
Results
All four tested plastic materials had a similar response to the tested conditions. Table 2 presents the results for one material. The results in the table show how different the effect of cleaning agents on ABS material is. When exposed to CIF, FROSCH and AJAX for 24 hours, the mechanical properties of the material do not change or change minimally. When exposed for 24 hours on the HOLLU LM, W5, HOLLU F9, there is a change in elongation at break.
We would assume that the results at the 24-hour exposure to the medium in the prestressed state will be similar only the differences will be more obvious but this is not the case. Mechanical properties deteriorate sharply in specimens exposed to HOLLU LM and HOLLU F9. At CIF and AJAX exposure, there was a significant reduction in rupture elongation. This means that the material retained its tensile strength but became much more brittle. Exposure to W5 in the prestressed state causes an improvement in elastic properties. The material retained the tensile strength of the elongation at break and greatly improved. The same effect is also seen when exposed to FROSCH only the intensity is lower.