Determination of bursting resistance of the hottes

Determination method of bursting resistance of paper and paperboard

this standard adopts the international standard iso2759 "paperboard - Determination Method of bursting resistance - the total export amount of the industry has decreased slightly"

1 subject content and scope of application

this standard specifies the method of determining the bursting resistance of paperboard by using the principle of hydraulic incremental method

this standard is applicable to various types of paperboard (including solid paperboard and corrugated paperboard) with a burst resistance of kPa (3..1kgf/cm)

this standard is not applicable to high elongation, 9-piston maximum stroke (mm) 250 and multilayer composite corrugated board

2 reference standard

gb/t450 paper and paperboard samples adopt

gb/t451.2 paper and paperboard quantitative determination method

gb/t4678 paper, paperboard, pulp terminology Part I

gb/t10739 standard atmosphere for pulp, paper and paperboard sample processing and testing

3 terminology

bursting strength, bursting index see 7.36 and 7.3 in gb/t4687-1984 from the ground discrimination cloth to see 7

4 principle

the instrument that meets the requirements clamps the sample between the upper and lower clamping plates with a certain pressure, and uses a reciprocating constant speed hydraulic pump to bulge the rubber film and the sample until the sample breaks. The maximum value of the applied hydraulic pressure is the bursting resistance of the sample

5 instrument

5.1 chuck system

to clamp the specimen firmly and evenly, the upper and lower chuck are two annular planes parallel to each other, and the annular surface is flat and grooved (see Appendix A). The dimensions of the chuck system are given in Appendix A

5.1.1 the upper chuck is connected with the pressure shaft with steel balls or similar movable joint devices to ensure uniform pressure distribution of the chuck

5.1.2 the upper and lower chucks shall be concentric, and the maximum error of concentricity shall not exceed 0.25mm. The surfaces of the two chucks shall be flat and parallel to each other. See Appendix B for the inspection method of chucks

5.1.3 in order to prevent the specimen from sliding, there should be sufficient clamping force between the two clamping discs, which is limited to not damaging the specimen. Generally, the clamping force is not less than 690kpa (7kgf/cm) (see Appendix C). When measuring the corrugated board, the pressure is 690kpa (7kgf/cm). Although sliding is prevented, most of the corrugated board is crushed. Because the compressive strength of corrugated board is different, the clamping pressure and whether the corrugated board is crushed should be indicated in the test report

5.2 adhesive film

5.2.1 the adhesive film is circular and made of rubber elastic materials. See Appendix F for its specifications and dimensions. However, after the tensile test, it is known that the sample is broken

5.2.2 when fixing the clamping film, the upper surface of the film is about 4.7MM lower than the upper surface of the lower chuck

5.2.3 the elastic resistance of the adhesive film is kPa (1.kgf/cm2) when the adhesive film protrudes 10mm from the surface of the lower chuck, and kPa (2..6kgf/cm2) when it protrudes 18mm

the adhesive film should be checked frequently. If it is found that the adhesive film does not meet the requirements, it should be replaced in time. When installing the adhesive film, drive away all the air gathered under the film

5.3 hydraulic system

use a piston to push a suitable liquid (such as chemically pure glycerol, ethylene glycol containing corrosion inhibitor or low viscosity silicone oil) and apply pressure under the film at a uniform speed until the sample breaks. The hydraulic system and the liquid used shall have no empty bubbles, and the liquid delivery volume of the piston shall be 170 ± 15ml/min (see attached table E). The piston must be driven by an electric motor

5.4 pressure gauge

5.4.1 Bourdon tube pressure gauge is used within the range of 25%-75% of the range of the pressure gauge. It must not be used in the range of less than 15% and more than 85%. The minimum diameter of the dial scale is 95mm, and the radian of the scale is not less than 270 °. The accuracy of any point within the working range shall be 0.5% of the maximum range of the dial. The pressure gauge shall have an air vent, and the dial shall be divided into at least 70 compartments

5.4.2 the expansibility of the pressure gauge shall be stable within 20% within the positive working range, and the liquid to be delivered shall not exceed 0.4ml even when reaching the maximum range (see Appendix E)

5.4.3 the friction moment between the pressure gauge and the pointer is about 0.3mn m。 The moment of inertia of the pointer should be within 2 (see Appendix D)

5.4.4 the operating inertia of the pressure sensor can be ignored, and the error between the barrier and the pressure recorder is within 0.2%. Digital display device. After the sample is broken, the reading change is not more than 1 unit

5.5 calibration

see Appendix D for the calibration of pressure gauge

see Appendix E for the inspection of hydraulic body

see Appendix C for the inspection of sample chuck

see Appendix F for the specifications and dimensions of the adhesive film

6 sampling, preparation and treatment

6.1 sampling shall be carried out according to the provisions of gb/t450, and each sample shall be cut into 100mm × 100mm。

6.2 the sample shall be treated with warm and wet treatment according to the provisions of gb/t10739

7 test steps

samples taken and treated according to standards must be tested under the specified standard temperature and humidity conditions

first select the appropriate measurement range. When it is necessary to predict, use a large range pressure gauge

place the sample between the upper and lower chuck. The specimen must exceed the entire area of the upper chuck. Lower the upper chuck and adjust it to the required pressure. Start the instrument and increase the pressure at an appropriate rate until the sample breaks. Return the piston until the rubber film is lower than the surface of the lower chuck, read the pressure value of the pressure gauge (or digital display), and then lift the upper chuck. The reading returns to zero for the next test

if it is found that the specimen slides or breaks abnormally due to crushing, this degree should be rounded off

stick 10 samples on the front and back sides of the samples cut evenly along the transverse paper web to the adhesive film for measurement, but do not press the samples that have been pressed by the chuck for testing in one test

8 calculation of test results

bursting index x (kpa.m2/g) is calculated by the following formula:

where: P - average bursting strength, kPa

w -- quantity of sample, g/m2

burst resistance and burst index take three significant figures

9 precision of test results

the precision of the results depends on the uniformity of the sample and other factors, such as the error of the pressure gauge, the clamping force, the pressure rate, whether there is air in the system, the rubber film, etc

numerical item repeatability reproducibility

range 3 5 5.. 6

generally 5 10

10 test report

the test report should include the following contents: the number of this national standard; Instrument and number used; Standard temperature and humidity conditions during the test

average value of burst resistance (report positive and negative results respectively when necessary)

if required, report the bursting index

coefficient of variation or 95% confidence interval of the reported results

the clamping pressure used in the measurement

when measuring the corrugated board, indicate whether the corrugated board is collapsed

what is the deviation from this method

reprinted from: Qilu printing art