ASTM C1735:17(R2021) pdf free download – Standard Test Method for Measuring the Time Dependent Modulus of Sealants Using Stress Relaxation.
Then remove the mechanical fasteners or rubber bands and the FTFE backing film. Keep the FIFE spacers and the aluminum substrate intact.
7.7 Allow specimen to cure according to the Test Method C719 specifications.
7.8 Test specimens surfaces should he smooth and free from nicks and scratches.
7.9 The finished test specimen is shown in Fig. 3.
8. Number of Test Specimens
8.1 Test at least three specimens of each sealant.
9. Procedure
9.1 Perform the lest at the standard conditions of temperature and relative humidity stated in 7.1. Tests at other ambient temperature and relative humidity may be run if desired.
9.2 Mount the specimen (as prepared in Section 7) in the fixture of the testing machine, Exercise precautions to minimize axial misalignment.
9.3 Set the testing machine al a crosshead displacement rate of 20 mm/mm (0.787 inimin). Set the direction of applied strain, either tensile or compressive.
9.4 Apply load to the specimen until the strain reaches the maximum strain, after which the specimen is completely unloaded at the same crosshead displacement rate.
95 The specimen is allowed to rest for 200 s. This is done to ensure the viscoelastic recovery from one loading is coniplete before the next loading is initiated.
9.6 Repeat 9.4 and 9.5 for the second loading-unloading
9.7 Set the testing machine at a crosshead displacement rate of 1000 nim/min (39.37 inimin).
9.8 Apply load to the specimen until the strain reaches the desired test strain, no greater than 3’S of the maximum strain and hold that value while load is monitored as a function of time. The time required to load the specimen is less than I s so the first data point is not taken until after 10 s to avoid transient effects associated with loading.
10.3 A pint of the tractional change in apparent rnxlulus is useful for comparison between different exposure times. For such a graph. no change would be represented as a horizontal straight line at F = 0. A horizontal line above or below F = 0 indicates that exposure causes a vertical shift in the stress relaxation curve hut no change in shape (that is, the time dependence does not change. Something other than a horizontal straight linc indicates a change in time dependence.
11. Report
11.1 Report the following information:
11.1.1 Identilication of the sealant tested, including type. source, manufacturer code number, curing conditions employed.
11.1.2 Identilication of the substraLe used,
11.1.3 Name and description of primers used, if any.
11.1.4 Temperature and relative humidity,
Il.l.5 Number of specimens tested,
11.1.6 Type of strain (compressive or tensile),
11.1.7 Maximum strain, test strain.
11.1.8 Descriptive of the type of failure, if any:
11.1.8.1 Cohesive failure, if separation occurred within the material,
11.1.8.2 Adhesive failure, if separation occurred at the interface of the substrate and the sealant.
11.1.8.3 Mixed failure. if both adhesive and cohesive failure regions are present.