BS ISO 289-2-2020 Rubber, unvulcanized – Determinations using a shearing-disc viscometer Part 2: Determination of pre-vulcanization characteristics.
1 Scope
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 usiq a shearing-disc viscoineter — 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:
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— IEC Electroped Ia: available at
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 I 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 highviscosity compounds.
6 Calibration schedule
See AiuixA.
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 preheating time shall be 1 mm, 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 corresponding prevulcanization times are designated t5 and t3, respectively. A typical trace obtained with the large rotor is shown in Figure 1.BS ISO 289-2 pdf download.