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GB/T 2794-2022 PDF in English


GB/T 2794-2022 (GB/T2794-2022, GBT 2794-2022, GBT2794-2022)
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GB/T 2794-2022: PDF in English (GBT 2794-2022)

GB/T 2794-2022
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 83.180
CCS G 38
Replacing GB/T 2794-2013
Determination for viscosity of adhesives
ISSUED ON: OCTOBER 12, 2022
IMPLEMENTED ON: MAY 1, 2023
Issued by: State Administration for Market Regulation;
Standardization Administration of the PRC.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative references ... 5
3 Terms and definitions ... 5
4 Sampling ... 5
5 Apparatus ... 5
6 Sample conditioning ... 7
7 Test methods ... 7
8 Result representation ... 9
9 Test report ... 9
Determination for viscosity of adhesives
1 Scope
This document describes methods for determination for the viscosity of adhesives using
single cylinder rotational viscometer, cone-plate rotational viscometer, and rotational
rheometer.
This document applies to the determination for viscosity of adhesives.
2 Normative references
The contents of the following documents, through normative references in this text,
constitute indispensable provisions of this document. Among them, for dated references,
only the edition corresponding to that date applies to this document. For undated
references, the latest edition (including all amendments) applies to this document.
GB/T 2918 Plastics - Standard atmospheres for conditioning and testing
GB/T 8170 Rules of rounding off for numerical values and expression and
judgement of limiting values
GB/T 20740 Adhesive - Sampling
3 Terms and definitions
This document does not have terms and definitions that need to be defined.
4 Sampling
Sample sampling shall be carried out in accordance with the provisions of GB/T 20740.
5 Apparatus
5.1 Single cylinder rotational viscometer
Measurement accuracy: ±5%.
5.2 Cone-plate rotational viscometer
Measurement accuracy: ±5%.
6 Sample conditioning
The samples shall be conditioned and tested in the standard conditioning environment
specified in GB/T 2918.
7 Test methods
7.1 Method 1: Single cylinder rotational viscometer method
7.1.1 Principle
A cylindrical or disc-shaped rotor rotates at a constant rate through the sample to be
tested. Measure the torque caused by the viscous drag; combine with the selected speed
and rotor type; obtain the viscosity value of the sample.
7.1.2 Test procedure
7.1.2.1 Add an appropriate amount of the sample to be tested into the sample holder as
needed, to ensure that no air bubbles are introduced. If necessary, use vacuum or other
suitable methods to eliminate air bubbles. If the sample is volatile or hygroscopic,
during the constant-temperature process, it shall seal the sample holder.
7.1.2.2 Select the appropriate rotor and speed, so that the meter reading is within
20%~90% of the maximum range.
7.1.2.3 Make sure that the sample temperature reaches the specified temperature.
Unless otherwise specified, the temperature of the test sample shall be kept at
(23.0±0.5)°C. When conducting arbitration, the thermometer shall be immersed in the
sample, to test the actual temperature of the sample.
7.1.2.4 Start the motor; the rotor rotates in the test sample. After the reading is stable,
record the data. When measuring the viscosity of some adhesives, if the reading
displayed by the instrument is unstable, the viscosity value should be read at a specified
time, such as 15 min. The time can also be determined through negotiation between the
two parties.
7.1.2.5 After each test, remove the rotor from the instrument. Use a solvent, which can
completely dissolve the sample, to carefully clean the rotor and cylinder.
7.1.2.6 Take two samples for parallel test, until the difference between the readings of
two consecutive sample tests is less than 3%. The result is the average of two
measurements.
7.2 Method 2: Cone-plate rotational viscometer method
7.2.1 Principle
Place the sample to be tested between the rotor and the plate. When the rotor rotates,
measure the torque caused by the viscous drag; combine with related parameters such
as the selected rotational speed and the diameter and angle of the rotor; obtain the
viscosity value of the sample.
7.2.2 Test procedure
7.2.2.1 According to the sample, select the appropriate instrument model, rotor and
speed; so that the instrument reading is within 10%~90% of the maximum range.
7.2.2.2 Make sure the viscometer is at the temperature required for the determination.
7.2.2.3 Zero the instrument.
7.2.2.4 Set the cone-plate gap.
7.2.2.5 According to the viscosity and thixotropy of the adhesive and the requirements
of the rotor, take an appropriate amount of the sample to be tested; place it in the center
of the plate; to ensure that the space between the rotor and the plate is filled with
adhesive. There shall be no excessive adhesive overflow. At the same time, ensure that
no air bubbles are introduced.
7.2.2.6 Wait for a period of time for the sample temperature to reach thermal
equilibrium, to ensure that the sample temperature is within the specified range. Unless
otherwise specified, the temperature of the test sample shall be kept at (23.0±0.5)°C.
7.2.2.7 Start the rotor. After the reading is stable, record the data.
7.2.2.8 After each test, use a solvent, which can completely dissolve the sample, to
carefully clean the rotor and plate.
7.2.2.9 Take two samples for parallel test, until the difference between the readings of
two consecutive sample tests is less than 3%. The result is the average of two
measurements.
7.3 Method 3: Rotational rheometer method
7.3.1 Principle
Apply strain (stress) to the rotor to test. According to the shear rate and shear stress,
measure the viscosity of the sample under the corresponding temperature conditions.
7.3.2 Test procedure
......
 
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.