This standard specifies the method for determining the longitudinal and transverse compressive strength of paper and paperboard using a short-distance compression tester. This standard applies to paper and paperboard used to make cartons and boxes, and also to paper sheets prepared by laboratories during pulp testing. This standard method stipulates that it cannot be used for strain measurement (see Al in Appendix A). GB/T 2679.10-1993 Method for determining the short-distance compressive strength of paper and paperboard GB/T2679.10-1993 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Method for determination of short span compressive strength of paper and boardPaper and boardCompressive strength-Short span testGB/T2679.10-93
This standard is equivalent to the international standard ISO9895:1989 "Short span test of compressive strength of paper and board". 1 Subject content and scope of application
This standard specifies the method for determining the longitudinal and transverse compressive strength of paper and board using a short span compression tester. This standard applies to paper and board used to make cartons and paper boxes, and also to paper sheets prepared by the laboratory during pulp testing. This standard method stipulates that it cannot be used for strain measurement (see A1 in Appendix A). 2 Reference standards
GB450 Paper and paperboard sample collection
GB451.2 Determination of paper and paperboard quantitative
GB10739 Standard atmosphere for handling and testing of pulp, paper and paperboard samples 3 Terminology
3.1 Compression strength
In the compression test, the maximum compression force per unit width of the paper and paperboard sample when it begins to fail is expressed in kN/m. 3.2 Compression index
Refers to the compression strength divided by the quantitative, expressed in (N·m)/g. 4 Principle
A 15mm wide sample is clamped between two clamps 0.7mm apart and compressed until it fails. The maximum compression force is measured and the compression strength is calculated.
5 Instrument
5.1 Compression Tester
The tester (see Figure 1) has two clamps for clamping 15mm wide specimens (see Figure 2), each of which has a fixed clamp and a movable clamp. The clamp is 30mm long and has a high friction surface. The clamp can clamp the specimen with a clamping force of 2300N±500N (gauge pressure 0.2～0.3MPa). The clamp is designed to firmly clamp the specimen over the entire width (see A1 in Appendix A). The two sides of the specimen are clamped by two fixed clamps and two movable clamps respectively. The clamping surfaces of the two fixed clamps are on the same plane of the same side of the specimen, while the clamping surface of the movable clamp is on the same plane of the other side of the specimen and should be parallel to the clamping surface of the fixed clamp. The requirements for parallelism should comply with the provisions of A2 in Appendix A. At the beginning of the test, the free spacing between the clamps is 0.7 ± 0.05 mm. After the test begins, along the length of the test paper strip, at both ends of the free spacing, one set of sample clamps moves relative to the other set of sample clamps at a speed of 3 ± 1 mm/min until the sample is squeezed and broken, then stops, and then returns to the starting position.
Approved by the State Administration of Technical Supervision on August 7, 1993 292
Implementation on March 1, 1994
GB/T 2679.10-93
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Figure 1 Short-distance compression tester
Figure 2 Short-distance compression tester clamps
C-Relative direction of clamp movement; S-Fixed clamp; M-Moving clamp; T-Sample The test instrument is equipped with a measuring and display device so that when the reading is within the effective range of 10% to 100% of the full scale, the reading error of the maximum compression force is less than ± 1%.
The test instrument is equipped with a calibration device, which uses a known weight base to calibrate the force sensor. The test instrument has a device that displays the clamping pressure. The corresponding relationship between the gauge pressure and the clamping force is as follows: Clamping pressure gauge gauge pressure
5.2 Paper cutting device
Specimen clamping force
Use a special paper cutting tool as shown in Figure 3. The cut sample edges should be neat and smooth and parallel. The width of the cut sample should be 15±0.1mm and the length should be 75mm. Other paper cutters that meet the requirements can also be used. 293
6 Calibration of the instrument
GB/T 2679.10—93
Check and calibrate the test instrument regularly. In the entire measuring range, select the calibration code at equal intervals for inspection. The deviation of any point within 10% to 100% of the full range cannot exceed ±1% of the reading. Figure 3 Paper cutting device
1 knife; 2-limiting plate; 3--sample; 4-limiting plate base If the instrument does not meet the calibration requirements, the instrument should be adjusted as necessary according to the manufacturer's instructions. 7 Sample collection and preparation
7.1 Sample collection shall be carried out in accordance with GB450 and temperature and humidity treatment shall be carried out in accordance with GB10739. 7.2 The preparation of the sample piece shall be carried out under the same standard atmospheric conditions as the temperature and humidity treatment. A paper strip of 75mm long and 15±0.1mm wide shall be cut from an undamaged paper sample. When the long side of the paper strip is parallel to the longitudinal direction of the paper, the longitudinal compression strength is measured. When the long side of the paper strip is parallel to the transverse direction of the paper, the transverse compression strength is measured.
Enough sample pieces should be cut to measure 10 strips in each direction. However, for paper and paperboard with poor uniformity, when the coefficient of variation of measuring 10 strips is greater than 10%, 20 strips should be measured.
8 Test steps
Select the clamping force according to the specified requirements, generally use a gauge pressure of 0.25MPa. Clamp the sample in the appropriate position of the sample clamp, press the sample clamp movement button, and read the indicated maximum compression force after the sample is squeezed and damaged. Repeat the above steps until all the samples to be tested are tested. 9 Calculation of test results
9.1 Result expression
Calculate the results obtained in the vertical and horizontal directions respectively. There is no difference in direction for laboratory hand-copied sheets. 9.2 Compression strength
Calculate the compression strength according to formula (1):
-Compression strength, kN/m;
Where: X-
F--maximum compression force, N;
15-sample width, mm.
GB/T 2679.10-93
Report the average compression strength, X is accurate to 0.01kN/m. 9.3 Compression index If necessary, calculate the compression index according to formula (2) [accurate to 0.1 (N·m)/g): 1000X
Where: Y—compression index, (N·m)/g; X—compression strength, kN/m;
G.---quantity, g/m\.
10 Precision
(2)
The variation between two tests of the same sample depends mainly on the structure of the paper. The following values ​​can be used as a reference for the precision of this method.
10.1 Repeatability of a test between instruments in the same laboratory
A certain amount of corrugated paper, boxboard and cardboard was tested simultaneously with four different testers side by side. The coefficient of variation of the test results (four averages of 10 tests) was generally less than 3%. 10.2 Reproducibility of the test between different laboratory instruments 10 test laboratories tested the same type of corrugated base paper with a basis weight of 112 to 180 g/m2 and the same type of kraft linerboard with a basis weight of 125 to 400 g/m2, and the coefficient of variation was between 3% and 7%. 11 Test report
The test report includes the following contents:
National standard number;
The temperature and humidity treatment conditions used;
The marking and description of the test sample;
The direction of the paper strip tested;
The number of repeated tests;bzxZ.net
The average result and the coefficient of variation;
Compression index;
Any deviation from the procedures specified in this standard or related factors that may affect the test results. 295
A1 Crushing strain
GB/T2679.10—93
Appendix A
Compression tester
(Supplement)
Under the condition that the specimen is not damaged, the clamp of the compression tester should firmly clamp the specimen, so the clamping force is distributed on one clamping surface. However, the specimen still slides slightly during the test. The strains of different parts of the specimen during the test are shown in Figure A1. The strain in the free area between the two clamps is the largest, and the strain in other clamped parts gradually decreases.
The crushing strain in the compression test is about 1%, that is, in a free spacing of 0.7mm, the crushing and deformation is only 7μm. Since the specimen slides in the clamp, the slight change in the free spacing and the slight movement of the clamp on the specimen plane do not affect the test results. However, the crushing strain cannot be calculated from the movement of the clamp, so the method described in this standard cannot be used for strain determination. Figure A1
A-Strain distribution; T-Specimen
A2Detailed description of the fixture
The edges of the four jaws in contact with the specimen at a spacing of 0.7mm should be square. The difference in free spacing measured at the top and bottom of the jaws is less than 0.03mm. The two parallel sides of the paper strip clamped by the fixed jaws are deviated near the free spacing, that is, the parallelism is not more than 0.01mm, and at the other end 30mm away, the deviation between the two is not more than 0.2mm, as shown in Figure A2. The bottom surfaces of the two jaws are parallel to each other, and the deviation of each point on them is not more than 0.1mm, as shown in Figure A3. 296
Additional Notes:
GB/T 2679.10—93
This standard was proposed by the Ministry of Light Industry of the People's Republic of China. This standard is under the jurisdiction of the National Technical Committee for Standardization of Paper Industry. This standard was drafted by the Paper Industry Scientific Research Institute of the Ministry of Light Industry. The main drafters of this standard are Zhang Shaoling, Chen Shuo, Li Lanfen, Han Xiuzhen and Wang Huajia. 297
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