Bent strip test - An environmental stress cracking test method
This method is used to investigate the chemical resistance of plastics in a bent strip test and assess environmental stress cracking (ESC).
The resistance of a plastic to stress cracking is determined by clamping test specimens across steel templates and placing them in contact with media. There are significant differences with regard to the mechanical properties after storing the plastics in air and under the influence of chemical agents.
The indicator property to be tested and the medium used are determined by the customer who commissions the test. Impact testing based on ISO 179/1fU is normally used as an indicator for the influence of a particular medium on the mechanical properties of plastics. Flat test specimens measuring 80 mm x 10 mm x 4 mm are the standard specimen type employed for these tests. The specimens are subsequently clamped across steel templates of different radii. Due to the variations in radius, different outer fibre strain values (between 0% and 2% in increments of 0.2%) are produced in the clamped test specimens. The specimens remain clamped for seven days prior to carrying out an impact test in accordance with ISO 179/1fU.
Standards for ESC and bent strip test
DIN EN ISO 22088-3, EN ISO 4599, DIN 53449-3, or equivalent standards
Other ways to test chemical resistance of plastics
|Internal stresses||PC ATI 104/86|
|Petrol test (isooctane/toluene)|
|Fuel resistance||DIN 51604-1
|Media aging, no load||DIN 53521