BS ISO 289-2:2020 pdf download – Rubber, unvulcanized — Determinations using a shearing-disc viscometer Part 2: Determination of pre-vulcanization characteristics This document specifies a method for determining the pre-vulcanization characteristics of compounded rubber. The pre-vulcanization characteristics determined by this method provide a means of estimating how long compounded rubber can be maintained at high temperatures and remain processable. 2 Normative references The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 289-1, Rubber, unvulcanized — Determinations using a shearing-disc viscometer — Part 1: Determination of Mooney viscosity 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. ISO and IEC maintain terminological databases for use in standardization at the following addresses: — ISO Online browsing platform: available at https:// www .iso .org/ obp — IEC Electropedia: available at http:// www .electropedia .org/ 3.1 pre-vulcanization time scorch time time including warm-up time, for the viscosity to increase by a specified amount from the minimum value Note 1 to entry: It is expressed in minutes. 4 Principle The test consists of determining how the Mooney viscosity of the rubber compound changes with running time at a specified temperature relevant to the process for which the compound is to be used. The time at which the Mooney viscosity has increased by a specified number of units is recorded. 5 Apparatus The apparatus specified in ISO 289-1 shall be used. It is permissible to use the small rotor for high- viscosity compounds. 6 Calibration schedule See Annex A. 7 Preparation of test specimen Prepare the two discs comprising the test specimen from a sheet of rubber compound, using the procedure for preparation of test pieces described in ISO 289-1. 8 Test temperature Choose a test temperature relevant to the process for which the compound is to be used. 9 Procedure Use the procedure described in ISO 289-1. The pre-heating time shall be 1 min, and the test shall be continued until the viscosity reaches the specified number of units above the minimum. When a large rotor is used, the increase is specified as five units and when a small rotor is used, the increase is specified as three units. The...
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