This standard specifies the method for determining the stiffness of paper and paperboard. The scope of application of this standard is generally 20mN~10000mN (equivalent bending moment is 2mN·m~1000mN·m) of paper and paperboard, but it can be as low as about 2mN for some instruments. This standard is also applicable to some materials with higher stiffness. This standard is only applicable to instruments with a bending angle of 7?5° or 15°. This standard is not applicable to the test of the stiffness of corrugated paperboard. GB/T 2679.3-1996 Determination of the stiffness of paper and paperboard GB/T2679.3-1996 Standard download decompression password: www.bzxz.net

GB/T 2679.3—1996
This standard is equivalent to the international standard ISO2493:1992 (Second Edition) "Paper and paperboard-Determination of stiffness". In this way, all instruments that meet the requirements of the standard can be used to measure the stiffness of paper and paperboard. When revising GB2679.3-81 "Method for determination of paperboard stiffness" according to ISO2493-1992, the test method and calculation of Taber stiffness instrument in GB2679.3-81 are retained, and L&W instrument is added as an instrument that meets the requirements of the standard. Chapter 3 "Definitions" in ISO2493-92 is changed to "Terms", and article numbers are added in Chapters 10 and 11. The article numbers and contents of other chapters remain unchanged. The foreword of ISO2493-1992 is retained, and "Foreword" is added. This standard will replace GB2679.3-81 from the date of entry into force. This standard is proposed by China Light Industry General Association.
This standard is under the jurisdiction of the National Technical Committee for Standardization of Paper Industry. The drafting unit of this standard is China Pulp and Paper Industry Research Institute. The main organizers of this standard are Ma Xin and Ji Houli. This standard was first promulgated in August 1981. bZxz.net
GB/T2679.3-1996
ISO Foreword
ISO (International Organization for Standardization) is a worldwide alliance organization of national standard bodies (ISO member countries). Usually, the work of formulating international standards is carried out by ISO technical committees. Each member interested in the topics established by the technical committee has the right to send representatives to participate in the technical committee. Governmental and non-governmental international organizations that have a relationship with ISO can also participate in this work. ISO and the International Electrotechnical Commission (IEC) jointly study all documents on electrotechnical standardization. The draft international standards adopted by the technical committee are voted on in a circular manner among the member countries. If at least 75% of the member countries vote in favor of passing the vote, they can be published as international standards.
International Standard ISO 2493 was prepared by Technical Committee ISO/TC 6, Paper, and Board, Subcommittee SC 2, Test methods and quality specifications for paper and board.
This second edition deletes and replaces the first edition (ISO 2493:1973) as a technical revision. 260
1 Scope
National Standard of the People's Republic of China
Determination of stiffness of paper and board
Paper and boardDetermination of resistance to bending
This standard specifies the method for determining the stiffness of paper and board. GB/T 2679.3-1996
eqv ISO 2493:1992
This standard is applicable to paper and board with a bending moment of 20 mN to 10 000 mN (equivalent bending moment of 2 mN·m to 1 000 mN·m) in general, but may be as low as about 2 mN for some instruments. This standard is also applicable to some materials with higher stiffness. This standard is only applicable to instruments with a bending angle of 7.5° or 15°. This standard is not applicable to the test of the stiffness of corrugated board. 2 Referenced standards
The provisions included in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised. Parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T450-89 Paper and paperboard specimens GB/T4687-84 Terminology for paper, paperboard, and pulp - Part - GB/T10739-89 Standard atmosphere for the treatment and testing of pulp, paper and paperboard specimens 3 Terms
This standard uses the following terms.
3.1 Stiffness
Under standard conditions, the force or moment when a specimen of specified size is clamped at the bending end to an angle of 15°. Expressed in mN or mN·m. 3.2 Bending length
The radial distance between the specimen clamp and the position where the specimen is subjected to force. 3.3 Bending angle
The angle between the initial position of the specimen and the position after the force is applied. 4 Principle
The force or moment required to bend a specimen clamped at one end to a given angle is measured, and the force acts on a constant bending length. 5 Instrument
A device that can measure the bending force or moment of the specimen as specified in 3.1, which meets the following requirements and has the required accuracy, can be used.
The bending angle is 15°±0.3° (7.5°±0.3°); the nominal bending length is 50mm, which can be modified according to the instrument manual; the State Administration of Technical Supervision approved on May 21, 1996 and implemented on December 1, 1996
GB/T 2679.3-1996
The fixture should be suitable for the requirements of width 38mm±0.2mm; the bending speed should be no less than 3s (L&W) but no more than 20s (Taber instrument) when bending at 15°; the reading is accurate to 2%.
The cutting device of the sample should meet the required requirements. 6 Calibration
The calibration and accuracy check of the instrument should be carried out regularly. The calibration method should be based on the type of instrument and refer to the instrument manual. Spring steel sheets can be used as samples for daily calibration checks. When using the Taber instrument, the friction of the pendulum shaft is very important, and its size should allow the pendulum to swing freely between 7.5° and 15° for no less than 10 times. 7 Sampling
The sampling of samples must be carried out in accordance with the provisions of GB/T450. 8 Temperature and humidity treatment
The samples must be treated in accordance with the provisions of GB/T10739, and prepared and tested under this condition. 9 Preparation of samples
Cut the sample into a rectangle with a length of 70mm and a width of 38mm±0.2mm. When measuring the longitudinal and transverse stiffness, the direction consistent with the length of the sample piece is the test direction. If the instrument used can only bend to one side, at least 10 samples are required. If the instrument can bend to two sides, 5 samples are required in each direction.
There should be no folds, wrinkles, visible damage or other defects on the test surface of the sample. If there is a watermark, it should be noted in the report. 10 Test steps
10.1 Clamp one end of the sample in the sample clamp. Be careful not to clamp the clamp too tightly to avoid damage to the sample and reading deviation. 10.2 When testing with the Taber apparatus, pay attention to aligning the specimen with the center scale of the pendulum. It is best to use the small roller distance adjustment device to adjust the sum of the distances between the specimen and the two small rollers to 0.33 mm ± 0.03 mm. According to the different stiffness of the specimen, select the measurement range by replacing the weight snake so that the reading of the specimen on the load plate is between 20 and 70 scales. 10.3 When using other types of instruments that meet the requirements of Chapter 5, the test should be carried out according to the method described in the manual of the instrument used. If the instrument is designed to bend only to one side, the number of bending tests on the front and back sides of the specimen should be the same during the measurement. Ten specimens should be used in each measurement direction to obtain 10 readings. If the instrument is designed to bend to both sides, the specimen is immediately read when it is bent to 15° to the side, and then the specimen is bent to 15° to the other side through the zero position and read. Ten readings can be obtained for five specimens on each side. After the test, the specimen removed from the specimen clamp cannot be reused. 10.4 If the stiffness of the specimen is too large or the specimen breaks when bent to an angle of 15°, the specimen can be bent to an angle of 7.5°. The measurement result can be multiplied by 2 to obtain an approximate value, but it must be noted in the report. 11 Calculation and representation of test results
11.1 The stiffness value is in mN·m. The stiffness measurement should be reported as the arithmetic mean when the specimen is bent to an angle of 15° in two directions. The calculation result is rounded to three significant figures. Note: If the instrument used cannot directly read the mN·m value, the reading value should be converted into mN·m units. 11.2 Calculate the standard deviation and coefficient of variation of the test results. 12 Test report
The test report should include the following contents:
This standard number;
Temperature and humidity treatment conditions;
GB/T 2679.31996
Type of instrument used. If Taber stiffness meter is used for testing, the selected measuring range should be indicated; Average stiffness, expressed in millinewtons or millinewtons meters, rounded to three significant figures. If the bending angle is not 15°, it should be indicated; Standard deviation and coefficient of variation of the test results should be reported if required; Any conditions that deviate from this standard.
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