GB/T 1232.1-2016 English PDF (GBT1232.1-2016)

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GB/T 1232.1-2016: Rubber, unvulcanized -- Determinations using a shearing-disc viscometer -- Part 1: Determination of Mooney viscosity
GB/T 1232.1-2016
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 83.060
G 40
GB/T 1232.1-2016 / ISO 289-1:2014
Replacing GB/T 1232.1-2000
Rubber, Unvulcanized – Determinations Using a Shearing-Disc
Viscometer – Part 1: Determination of Mooney Viscosity
(ISO 289-1:2014, IDT)
ISSUED ON: OCTOBER 13, 2016
IMPLEMENTED ON: MAY 01, 2017
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine;
Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword ... 3
1 Scope ... 6
2 Normative References ... 6
3 Principle ... 7
4 Apparatus ... 7
5 Preparation of Test Piece ... 12
6 Temperature and Duration of Test ... 13
7 Procedure ... 13
8 Expression of Results ... 14
9 Precision ... 14
10 Test Report ... 14
Annex A (Informative) Precision Statement ... 16
Annex B (Informative) Heat-Stable Film for Mooney Viscosity Measurements ... 19
Annex C (Normative) Calibration Schedule ... 23
Rubber, Unvulcanized – Determinations Using a Shearing-Disc
Viscometer – Part 1: Determination of Mooney Viscosity
WARNING -- Persons using this Part should be familiar with normal laboratory practice.
This Part does not purport to address all of the safety problems, if any, associated with its
use. It is the responsibility of the user to establish appropriate safety and health practices
and to ensure compliance with any national regulatory conditions.
1 Scope
This Part of GB/T 1232 specifies a method, using a shearing-disc viscometer, for measuring the
Mooney viscosity of uncompounded or compounded rubbers.
This Part is applicable to the determination of Mooney viscosity of uncompounded and
compounded rubbers.
2 Normative References
The following documents are essential to the application of this document. For the dated
documents, only the versions with the dates indicated are applicable to this document; for the
undated documents, only the latest version (including all the amendments) is applicable to this
document.
ISO 1795 Rubber, Raw Natural and Raw Synthetic – Sampling and Further Preparative
Procedures
ISO 2393 Rubber Test Mixes – Preparation, Mixing and Vulcanization – Equipment and
Procedures
ISO 6508-1 Metallic Materials – Rockwell Hardness Test – Part 1: Test Method
ISO/TR 9272 Rubber and Rubber products – Determination of precision for Test Method
Standards
ISO 18899:2013 Rubber – Guide to the Calibration of Test Equipment
ISO 23529 Rubber – General Procedures for Preparing and Conditioning Test pieces for
Physical and Test Methods
The two dies forming the cavity shall be formed from non-deforming unplated hardened steel
of minimum Rockwell hardness 60 HRC (see ISO 6508-1). The dimensions of the cavity are
given in Figure 1 and shall be measured from the highest surfaces. For good heat transfer, each
die should preferably be made from only one piece of steel. The flat surfaces shall have radial
V-grooves to prevent slippage. The grooves shall be spaced radially at 20° intervals and shall
extend from an outer circle of diameter 47 mm to an inner circle of diameter 7 mm for the upper
die and to within 1.5 mm of the hole in the lower die; each groove shall form a 90° angle in the
die surface with the bisector of the angle perpendicular to the surface and shall be 1.0 mm ± 0.1
mm wide at the surface (see Figure 2).
4.3 Rotor
The rotor shall be fabricated from non-deforming unplated hardened steel of minimum
Rockwell hardness 60 HRC. The rotor surfaces shall have rectangular-section grooves 0.80 mm
± 0.02 mm wide, of uniform depth 0.30 mm ± 0.05 mm, and spaced 1.60 mm ± 0.04 mm apart
(distance between central axes). The flat surfaces of the rotor shall have two sets of such grooves
at right angles to each other (see Figure 3). The edge of the rotor shall have vertical grooves of
the same dimensions. The large rotor shall have 75 vertical grooves and the small rotor shall
have 60. The rotor is fastened at right angles to a shaft having a diameter of 10 mm ± 1 mm and
a length such that, in the closed die cavity, the clearance above the rotor does not differ from
that below by more than 0.25 mm. The rotor shaft shall bear on the spindle which turns the rotor
shaft, not on the wall of the die cavity. The clearance at the point where the rotor shaft enters
the cavity shall be small enough to prevent the rubber from leaving the cavity. A grommet, O-
ring, or other sealing device can be used as a seal at this point.
The eccentricity or runout of the rotor while turning in the viscometer shall not exceed 0.1 mm.
The angular velocity of the rotor shall be 0.209 rad/s ± 0.002 rad/s (2.00 r/min ± 0.02 r/min).
4.4 Heating device
The dies are mounted on, or form part of, platens equipped with a heating device capable of
maintaining the temperature of the platens and that of the dies to within ±0.5 °C of the test
temperature. After insertion of the test piece, the devices shall be capable of returning the
temperature of the dies to within ±0.5 °C of the test temperature within 4 min.
NOTE: Older machines might not comply with these requirements and might give less reproducible
results.
2 - measurement probe, inserted;
3 - stop connected to apparatus;
4 - stop connected to measurement probe.
Figure 4 -- Measurement-Probe Design
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 ± 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 1 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, 50, 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...