ISO 2285:2013 pdf download – Rubber, vulcanized or thermoplastic – Determination of tension set under constant elongation, and of tension set, elongation and creep under constant tensile load
1 Scope
This International Standard specifies a number of methods of determining the dimensional changes in test pieces of vulcanized or thermoplastic rubber during and after tensile loading for relatively short periods under constant elongation or constant loading. The constant-elongation test is intended to measure the ability of rubbers to retain their elastic properties after extension, at a standard laboratory temperature, to a specified strain which is maintained for a specified time at the same or at a specified higher temperature and then released at the test temperature or at the standard laboratory temperature. The constant-load test specifies a method for the determination of elongation, creep and tension set of rubbers subjected to a constant load at standard laboratory temperature. The test methods are intended to measure the elastic properties of rubber in the hardness range 20 IRHD to 94 IRHD. The creep measurement is not recommended for product design or the evaluation of low-creep materials. For these, reference should be made to ISO 8013. No agreement between the results of this test and those of ISO 8013 should be inferred. NOTE The constant-load test is primarily intended for the measurement of state of cure and the quality control of thin-walled products. An increase in the state of cure or degree of crosslinking is usually reflected in a decrease in set, creep or elongation.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply (see also the definitions of creep functions given in ISO 8013).
3.1 tension set at constant load
elongation remaining in a test piece in the unloaded condition after it has been subjected to a constant load during a specified time, expressed as a percentage of the original length in the unloaded condition
3.2 tension set at constant elongation
elongation remaining in a test piece in the relaxed condition after it has been subjected to a constant elongation during a specified time, expressed as a percentage of the elongation
3.3 creep
increase in elongation of a test piece at constant load during a specified time, expressed as a percentage of the elongation at the beginning of that time
4.1.1 Straining device, consisting of a metal rod or other suitable guide fitted with pairs of holders, one fixed and one moveable, for the ends of the test piece. The holders shall be in the form of self-tightening clamps for strip test pieces, in the form of jaws to hold tab (enlarged) ends, and in the form of flat pulleys of about 5 mm width and 10 mm diameter for ring test pieces. If so desired, a means of operating the moving holder other than by hand may be provided, for example a threaded rod. Suitable stops or graduations may also be provided to avoid over-extension in the initial straining of the test piece. The straining device shall be so designed that, when used at high temperatures in an oven, it can be placed with the reference length of the test piece perpendicular to the direction of the air flow. It shall also be of minimum mass in order to avoid excessive lag in the attainment of temperature equilibrium after its introduction into the oven. A multiple-unit straining device may be used, provided that the foregoing requirements are met.