BS ISO 03384-2:2012 pdf download
BS ISO 03384-2:2012 pdf download.Rubber, vulcanized or thermoplastic- Determination of stress relaxation in compression Part 2: Testing with temperature cycling.
5.2 Counterforce.measurlng device, capable of measuring compression forces In the desired range with an accuracy of 1 % of the measured value.
The continuous-measurement system monitors the test piece during the whole duration of the test, thus making continuous measurement of the change in counterforce with time possible. The deformation of the test piece shall be kept within ±0.01 mm for the duration of the ted
5.3 Temperature chamber: For tests in air, a well designed, uniformly heated air temperatLire chamber shall be used, complying, for temperatures above standard laboratory temperature, with the requirements specified for one of the ovens used in ISO 188:2011, method A.
For cycling the temperature, the temperature chamber shall have a cooling and heating capability and be able to change the temperature at a rate of 1,0 °C/min ± 0,5 °C/min.
In the case of high-temperature tests and to avoid the surface oxidation of test pieces, other atmospheres may be used, such as nitrogen. For tests in liquids, the compression device shall be totally immersed in the liquid In a bath, or a closed vessel for volatile or toxic fluids, such that free circulation of the liquid can take place through the holes in the compression plates. The liquid shall be maintained at the specified temperature by proper control of a heater and circulation of the liquid in the bath or, alternatively, by placing the liquid bath and compression device within a temperature chamber as specified above.
NOTE IL is recommended that the air used for air exchange be passed through an air dryer to give it a dew point not higher than -40°C In order to avoid Ice formation which can introduce friction In the measuring system.
5.4 Temperature-measurIng equipment, with a sensing element having appropriate precision. The temperature-sensing element shall be installed in such a way that it accurately measures the temperature of the test piece.
NOTE A P1100 sensor has been found to be suitable for temperature measurement.
6 Calibration
The requirements for calibration of the test apparatus are given in Annex A.
7 Test piece
7.1 Type and preparation of test piece
7.1.1 General
Test pieces shall be prepared either by moulding or by cutting from moulded sheets or products, In accordance with ISO 23529.
NOTE The results obtained from test pieces of different sizes are not comparable.
7.1.2 Cylindrical test pieces
The test piece shall be a cylindrical disc of diameter 13,0mm ± 0,5 mm and thickness 6,3 mm ±0,3 mm.
7.1.3 Ring test pieces
The preferred ring test piece is a ring of square cross-section cut from a flat sheet of the test material by means of rotary cutters. For a suitable machine for the preparation of small ring test pieces, see Annex A of ISO 37:2011.
The dimensions of test pieces shall be:
— thickness: 2,0 mm ± 0,2 mm
— Inner dIameter: 15.0mm ± 0,2 mm
— radial width: 2,0mm ±0.2mm
The sheets may be prepared by moulding or from finished articles by cutting and buffing.
Alternatively, an 0-ring with an internal diameter of 14,0 mm and a cross-section diameter of 2,65 mm may be used as the standard test piece.
0-rings of other dimensions, together with seals or gaskets of other configuration. may he used as nonstandard test pieces, where appropriate.
7.2 Measurement of dimensions of test pieces
The dimensions oltest pieces shall be measured as specified In ISO 23529.
7.3 Number of test pieces Thepreferrednumberoftestpiecesisthree,hutforroutineandscreeningteststwotestpiecesareacceptahle.
7.4 TIme Interval between forming and testing
The interval between forming and testing shall be in accordance with Iso 23529.
73 Conditioning of test pieces
7.5.1 Prior Lo testing, the test pieces shall undergo first thermal and then mechanical conditioning as detailed In 7.52 and 73.3. When using method A at elevated temperature, the thermal conditioning might not be required, as the preheating of the test piece before compression acts as thermal conditioning.
7.5.2 Thermal conditioning shall be carried out by heating the test pieces at 70 C for 3 h. Following thermal conditioning. the test pieces shall be allowed to stand bra period of not less than 16 hand not more than 48 h at standard laboratory temperature prior to mechanical conditioning or testing.
NOTE Some test samples, especially of thermoplastic elastomers, might contain moulding stresses, and thermal condIuonng to relieve these stresses might mmprove the reproducibility of the results.
7.5.3 Mechanical conditioning shall be carried out at one of the standard laboratory temperatures specified in ISO 23529, as follows.
