ISO 37:1994 pdf download.Rubber, vulcanized or thermoplastic - Determination of tensile stress-strain properties
7.4.1 The tensile- testing machine shall comply with the requirements of ISO 5893: 1993, having an accu-racy of force measurement complying with grade Band, where used, an extensometer accuracy comply-ing with grade D1 for type 1 and 2 dumb-bell and type A ring test pieces, and grade E1 for type 3 and 4 dumb-bell and type B ring test pieces. The machine shall as a minimum be capable of operating at a rate
of traverse of 100 mm/min, 200 mm/min and 500 mm/min and should preferably be equipped with facilities for the autographic recording of stress and strain.
7.4.2 For tests at temperatures other than standard temperature, a suitable thermostated chamber shall be fitted to the tensile testing machine. Guidance for achieving elevated or subnormal temperatures is given in ISO 3383.
Measure the thickness at the centre and at each end of the test length with the thickness gauge. The median value of the three measurements shall be used in calculating the area of the cross-section. In any one dumb-bell, none of the three thickness measurements of the narrow portion shall differ by more than 2 % from the median thickness. If two groups of test pieces are being compared, the median thickness of each group shall be within 7,5 % of the median thickness of the two groups. The width of the test piece shall be taken as the distance between the cutting edges of the die in the narrow part, and this distance shall be measured in accordance with Iso 4661-1 to the nearest 0,05 mm.
13.1 Dumb-bell test pieces
Insert the test piece into the tensile-testing machine. ensuring that the parallel-sided portions of the tab ends are gripped symmetrically so that the tension is distributed uniformly over the cross-section. If necessary, set up the extensometry device. Start the machine and monitor continuously the change in test length and force throughout the test to an accuracy within ± 2 %, as required for the purposes of clause 15.
Condition all test pieces in accordance with ISO 471.If the preparation of test pieces involves buffing, the interval between buffing and testing shall be not less than 16 h and not greater than 72 h.
For tests at standard temperature, test pieces that do not require further preparation may be tested im-mediately, if cut from conditioned test samples.
Where additional preparation is involved, a minimum conditioning period of 3 h at standard temperature shall be allowed.
For tests at temperatures other than standard tem-perature, condition the test pieces at the temperature at which the test is to be conducted for a period suf-ficient to enable test pieces to attain substantial equilibrium in accordance with ISO 3383 (see 7.4.2).ISO 37 pdf download.