ASTM C1735-17 (R2021) pdf download.Standard Test Method for Measuring the Time Dependent Modulus of Sealants Using Stress Relaxation.
1.1 This test method covers a procedure for measuring the time dependence of modulus in elastomeric joint sealants in a test specimen configuration described in Test Method C719. These sealant materials are typified by highly filled rubber materials. Any Mullins eliect is first assessed and mitigated in two loading-unloading cycles. Time dependence of modulus in materials is then determined using a stress relaxation procedure.
1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses after Si units are provided for information only and arc not considered standard.
3 Terminology
3. 1 Definitions:
3. 1 . 1 For definitions of terms used in this test method, refer to Terminologies E63 1 and C717.
4. Summary of Test 1Iethod
4.1 This test method consists of two loading cycles where strain is increased from a 0 % to a user-defined maximum strain and one stress relaxation procedure at a strain for greater than of the user-defined maximum strain. A schematic diagram of this test strain history is shown in Fig. 1.
4.2 The motivation for the two loading-unloading cycles is to assess if any Mullins effect is present and to mitigate any of this effect in the subsequent stress relaxation test. As long as the maximum strain achieved during the first deformation is not exceeded, however, all subsequent loadings follow the same stress-strain curve.
4.3 Stress relaxation procedure is based on a sudden imposition of either a tensile or compressive strain on the test specimen at a value of no more than 2h of the maximum strain and the measurement of the load required to maintain this tensile or compressive strain as a function of time.
4.4 The conversion of load relaxation values to apparent modulus and fractional change in apparent modulus is accomplished by inputting information about the specimen geometry and the amount of deformation into an equation that is based on the statistical theory of rubber-like elasticity.
5. Significance and Use
5.1 The intent of this test method is to determine the time dependence of modulus in building joint sealants using two loading-unloading cycles to identify and mitigate any Mullins effect, and followed by a stress relaxation procedure to determine the time dependent modulus.ASTM C1735 pdf download.