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:
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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 corresponding pre-vulcanization times are designated t 5 and t 3 , respectively. A typical trace obtained with the large rotor is shown in Figure 1.
10 Precision
See Annex B.
11 Test report
The test report shall include the following information:
a) sample details:
1) full description of the sample and its origin;
2) details of compounded rubbers, if applicable;
b) details of the preparation of the test pieces,
c) a reference to this document, i.e. ISO 289-2:2020;
d) a description of the apparatus used, including the model used, the manufacturer of the apparatus
and the rotor size (large or small),
e) test details:
1) the test temperature;
2) the die-closing force, if other than 11,5 kN;
3) details of any procedures not specified in this document;
f) test results:
1) the minimum viscosity, in Mooney units;
2) the pre-vulcanization or scorch time (t 5 or t 3 ), in minutes;
g) date(s) of test.BS ISO 289-2 pdf download.