ISO 289-1:2015 pdf download – Rubber, unvulcanized — Determinations using a shearing- disc viscometer — Part 1: Determination of Mooney viscosity.
4.7 Torque-measurement device and calibration of the device The torque required to turn the rotor is recorded or indicated on a linear scale graduated in Mooney units. The reading shall be zero when the machine is run empty and 100 ± 0,5 when a torque of 8,30 N⋅m ± 0,02 N⋅m is applied to the rotor shaft. Therefore, a torque of 0,083 N⋅m is equivalent to one Mooney unit. The scale shall be capable of being read to 0,5 Mooney units. Variation from zero shall be less than ±0,5 Mooney units when the machine is running with the rotor in place and the dies closed and empty. If the viscometer is equipped with a rotor-ejection spring, the zero calibration shall be made with the dies open so that the rotor is not pressing against the upper die. The viscometer shall be calibrated while the machine is running at the test temperature. A suitable method for the calibration of most machines is as follows. The scale is calibrated to a reading of 100 by applying certified masses fastened with flexible wire to an appropriate rotor. During calibration, the rotor is turned at 0,209 rad/s and the platens are at the specified test temperature. NOTE In order to check linearity, intermediate masses can be used to give scale readings of 25 Mooney units, 50 Mooney units, and 75 Mooney units, respectively. In addition, a sample of butyl rubber of certified Mooney viscosity can be used to check whether or not the machine is working correctly. Measurement can be carried out at 100 °C or 125 °C for 8 min.
5 Preparation of test piece For uncompounded rubbers, the test piece shall be prepared in accordance with ISO 1795 and the material standard relevant to the rubber. For compounded rubbers which are to be tested for referee purposes, the test piece shall be taken from a compound prepared in accordance with ISO 2393 and the material standard relevant to the rubber. The test piece shall be allowed to rest at standard laboratory temperature (see ISO 23529) for at least 30 min before testing is carried out. Testing shall be commenced not later than 24 h after homogenization. The Mooney viscosity is affected by the manner in which the rubber is prepared and the conditions of storage. Accordingly, the prescribed procedure in methods for evaluating a particular rubber shall be followed rigorously. The test piece shall consist of two discs of rubber, of diameter about 50 mm, and of thickness approximately 6 mm sufficient to fill completely the die cavity of the viscometer. The rubber discs shall be as free as possible from air and from pockets that could trap air against the rotor and die surfaces. A hole is pierced or cut through the centre of one disc to permit the insertion of the rotor shaft.