ISO 17278-2020 pdf download.Rubber, raw natural – Determination of the gel content of technically specified rubber (TSR) 5.2 Acetone, analytical grade. 6 Apparatus 6.1 Laboratory centrifuge, capable of rotating at a minimum of 14 000 r/min (revolutions per minute). If the above speed cannot be attained a minimum speed of 8 000 r/min may be used with a longer running time (8.ZA). NOTE When the centrifugal rotational frequency (rotational speed) is 14 000 r/min, the gravitational acceleration is 22 000g. When the centrifugal rotation speed is 8000 r/min, the gravitational acceleration is 7000g. 6.2 Screw-cap centrifuge tubes, with a minimum capacity of 30 cm3, capable of withstanding the centrifuge conditions and of being heated to a temperature greater than 110 °C. 6.3 Balance, capable of accurately weighing to ± 0,1 mg. 6.4 Laboratory oven, gravity convection type, capable of controlling the temperature to ± 10 °C. 6.5 WeIghing container, I.e. an aluminium box or plate for weighing. 7 Conditions Laboratory conditions shall be controlled in accordance with ISO 23529. 8 Procedure 8.1 Number of test samples Two test samples shall be taken in accordance with Clause 7 of ISO 2000:20 14. 8.2 Procedure 8.2.1 Take a test sample from a bale without milling of mass calculated at the ratio of 0,1 g per 30 cm3 of toluene. NOTE When the volume of a centrifuge tube is 50 cm-i, the volume of toluene is 30 cm3 (see 82.3). and the sample weight is 0,1 g. 8.2.2 Cut the test sample into approximately 1 mm3-sized pieces using clean scissors. Weigh the prepared test pieces to the nearest 0,1 mg (m0). Place the pieces in a clean centrifuge tube (f2), which has previously been heated at 100 °C for 1 h and stored in a desiccator. 8.2.3 Add toluene to the tube until it is 60 % full. Cap it and shake by hand for a few seconds. Then. allow It to stand for 16 h to 20 h in dark conditions without stirring at (25 ± 2) °C.ISO 17278 pdf download.
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