BS ISO 03384-1:2011 pdf download

BS ISO 03384-1:2011 pdf download.Rubber, vulcanized or thermoplastic —Determination of stress relaxation in compression Part 1: Testing at constant temperature.
Measure the axial thickness of each test piece with an accuracy of 001 mm at four points approximately 90’ apart around the ring after thermal conditioning and before mechanical conditioning, at the chosen standard laboratory temperature. as specified in ISO 23529 Use the average of the measurements to calculate the necessary compression. lndivioual measurements, on a srngle test piece, shall not differ by more than 0.05 mm If they do. discard the test piece.
8.3 Method A
8.3.1 Bnng the compression device and the test environment to the test temperature.
8.32 When testing in a liquid, the lest piece and the operating surfaces of the compression device shall be gently lubricated with the test liquid. When testing in a gaseous mecum, a thin coating of a lubricant having substantially no action on the rubber shall be applied (see 8.1).
8.3.3 Immediately after lubrication, condition the test piece at the test temperature In accordance with ISO 23529. Conditionmg for at least 30 nn Is recommended. For temperatures upwards of 150 ‘C. longer limes are necessary In accordance with ISO 23529.
8.3.4 Place the conditioned test piece in the preheated compression device (5.1) or, if the preheating is done in the compression device, place the test piece in the device and then preheat, Compress the test piece by (25±2) % in the compression device at the test temperature or. If a compression of 25 % cannot be obtained, use a compression of (15 * 2) % or lower, in steps of 5%. Compress the test piece in a time between 30 s and 120 s. When reached, the final compression shall be fixed and mamtained during the entire test period (apart from the further small compression which is used for measurement of the counterforce as mentioned in the alternative method in 5.2).
8.3.5 Measure the initial counterforce with an accuracy of 1 % of the measured value, at the test temperature. 30 mm ± 1 mm after completing the compression
8.3.6 Repeat the measurement of the counterforce F, after the times specified in 7.1. Take all measurements at the test temperature.
After the last measurement at the test temperature, the test piece may be allowed to cool down to standard laboratory temperature and a further measurement of the counterforoe made.
NOTE Valuable additional iformation can be obtained after the relaxation lest has been feshed Research has shown that the amoa’it of recovery (at the test temperature) is a measure of the permanent chemIcal reactions occurring alongside physical relaxation (see Reference (4)).
8.4 Method B
8.4.1 Bring the test environment to the test temperature.
8.4.2 When testing in a liquid, the lest piece and the operating surfaces of the compression device shall be gently lubricated with the test liquid. When testing in a gaseous medium, a thin coating of a lubricant having substantially no action on the rubber shall be applied (see 8.1).
8.4.3 Compress the test piece by (25 ± 2) % in the compression device at a standard laboratory temperature or, if a compression of 25% cannot be obtained, use a compression of (15 2) % or lower, in steps of 5 %. Compress the test peace in a time between 30s and 120 s. When reached, the final compression shall be fixed and maintained during the entire test period (apart front the further small compression which is used for measurement of the counterforce as mentioned in the alternative method in 5.2).
8.4.4 Measure the initial counterforce F0 with an accuracy of 1 % of the measured value, at standard laboratory temperature, 30 mm ± 1 mm after completing the compression.
The median value of the results for the test p.eces shall be ctiosen. The individual values for the test pieces shall agree 10 within 10 % of the median value. If they do not the test shall be repeated.
Stress relaxation values measured after different times or exposure shall be plotted as a function or time on a logarithmic scale to facilitate the interpretation of the test data. For some applications, it is more useful to calculate compression stress ratio values, i.e F,1F0. after different times of exposure, rather than stress relaxation values In this case. compression stress ratio values shall be presented graphically as a function of loganthmic time.