1、T 807 om-11 SUGGESTED METHOD 1965 OFFICIAL STANDARD 1975 OFFICIAL TEST METHOD 1982 REVISED 1987 REVISED 1994 REVISED 1999 REVISED 2003 REVISED 2008 REVISED 2011 2011 TAPPI The information and data contained in this document were prepared by a technical committee of the Association. The committee and
2、 the Association assume no liability or responsibility in connection with the use of such information or data, including but not limited to any liability under patent, copyright, or trade secret laws. The user is responsible for determining that this document is the most recent edition published. Ap
3、proved by the Standard Specific Interest Group for this Test Method TAPPI CAUTION: This Test Method may include safety precautions which are believed to be appropriate at the time of publication of the method. The intent of these is to alert the user of the method to safety issues related to such us
4、e. The user is responsible for determining that the safety precautions are complete and are appropriate to their use of the method, and for ensuring that suitable safety practices have not changed since publication of the method. This method may require the use, disposal, or both, of chemicals which
5、 may present serious health hazards to humans. Procedures for the handling of such substances are set forth on Material Safety Data Sheets which must be developed by all manufacturers and importers of potentially hazardous chemicals and maintained by all distributors of potentially hazardous chemica
6、ls. Prior to the use of this method, the user must determine whether any of the chemicals to be used or disposed of are potentially hazardous and, if so, must follow strictly the procedures specified by both the manufacturer, as well as local, state, and federal authorities for safe use and disposal
7、 of these chemicals. Bursting strength of linerboard 1. Scope and summary 1.1 This method describes a procedure for measuring the bursting strength of linerboard using a disk shaped diaphragm. Basis weights for this method should be 98 g/m2(20#/MSF) and higher. The minimum burst should be 350 kPa (5
8、1 psi). This method may also be used to test paperboard. 1.1.1 A specimen is clamped between two platens with circular openings in their centers. An expansible diaphragm is distended through the lower platen by means of hydraulic pressure until the specimen ruptures. The maximum hydraulic pressure w
9、hen the specimen ruptures is recorded. 1.2 For the bursting strength of paper with basis weights below 98 g/m2, use TAPPI T 403 “Bursting Strength of Paper.” For corrugated combined board, see TAPPI T 810 “Bursting Strength of Corrugated Board.” 2. Significance The bursting strength test of linerboa
10、rd (and paperboard) is a composite measure of certain properties of the sheet structure, principally tensile strength and elongation. In general, bursting strength is dependent on the type, proportion, preparation, and amount of fibers present in the sheet and on their formation, internal sizing, an
11、d, to some degree, the surface treatment. While bursting strength is an empirical property, this test, in combination with grammage (basis weight), serves to define some “standard grades” in commerce. The bursting strength relates to sidewall puncture of the finished combined board and has been show
12、n to be important in mixed load LTL types of shipments. See TAPPI T 810 for testing burst on combined board and boxes. 3. Apparatus 3.1 Bursting tester1, consisting of the following: Names of suppliers of testing equipment and materials for this method may be found on the Test Equipment Suppliers li
13、st, available as part of the CD or printed set of Standards, or on the TAPPI website general Standards page. T 807 om-11 Bursting strength of linerboard / 2 3.1.1 Means for clamping the test specimen between two annular, plane surfaces having fine concentric tool marks to minimize slippage. The uppe
14、r clamping platen (clamping ring) has a diameter of approximately 95.3 mm (3.75 in.), with a circular opening 31.50 0.03 mm (1.240 0.001 in.) diameter. The lower edge of the opening (side in contact with the board) has a 0.64-mm (0.025-in.) radius. The lower clamping surface (diaphragm plate) has an
15、 opening 31.50 0.03 mm (1.240 0.001 in.) in diameter and an outer diameter greater than or equal to the upper platen. The upper edge of the opening (in contact with the board) has a 0.40-mm (0.016-in.) radius and the lower edge of the opening (in contact with the rubber diaphragm) has a radius of 3.
16、18 mm (0.125 in.) to prevent cutting the rubber when pressure is applied. 3.1.2 The upper clamping ring is connected to the clamping mechanism through a swivel joint to facilitate an even clamping pressure. The openings in the two clamping plates are required to be concentric to within 0.13 mm (0.00
17、51 in.), and their clamping faces must be flat and parallel (see Appendix A.1.1). 3.1.3 A molded (disk-shaped) diaphragm requiring a pressure of at least 160 kPa but not more than 210 kPa (at least 23 psi but not more than 30 psi) to distend it to a height of 9.53 mm (0.375 in.) above the diaphragm
18、plate (see Appendix A.1.2.). Diaphragms that require more pressure to distend may lead to artificially high readings. 3.1.4 Means of forcing liquid into the pressure chamber below the diaphragm at a steady rate of 170 15 mL/min (5.75 0.5 oz/min). This pressure is generated by a motor driven piston,
19、rotary pump, or other suitable method for forcing a hydraulic fluid into the pressure chamber of the apparatus (see Appendix A.1.3). 3.1.5 A pressure gauge of the maximum reading or the lazy hand type. The scale has a radius of 47.6 mm (1.875 in.) with graduations extending over a minimum arc of 270
20、 indicating bursting pressure in kPa (psi), with an accuracy of 0.5% of full scale and must have sufficient capacity so that all readings can be maintained in the middle half of the scale. In its operating position, the gauge should be inclined between horizontal and 30 from the horizontal. When mor
21、e than one gauge is mounted on a single apparatus, only the gauge on which the measurement is being made is open to the hydraulic system so as not to reduce the rate of distension of the test specimen. 3.1.6 Calibrate the gauges before initial use and frequently enough to ensure their specified accu
22、racy (weekly or monthly as needed, or before using if they have been idle for a month or more). Calibrate the gauges while inclined at the same angle as used during a test. During calibration, apply the pressure so that the rate of travel of the needle is similar to that when actually testing the bo
23、ard. If a gauge is accidentally subjected to a pressure beyond its capacity, recalibrate it before it is again used (see Appendix A.1.4). 3.1.7 As an alternative to 3.1.5, a pressure transducer with equivalent accuracy and suitable signal processing circuitry to display the maximum bursting pressure
24、 may be used provided it gives comparable results. 4. Sampling and test specimens From each test unit obtained in accordance with TAPPI T 400 “Sampling and Accepting a Single Lot of Paper, Paperboard, Containerboard, or Related Product,” select 10 or more specimens, each with areas at least 100 100
25、mm (4 4 in.), preferably larger. 5. Conditioning Condition the specimens and make the tests in the conditioning and testing atmosphere specified in TAPPI T 402 “Standard Conditioning and Testing Atmospheres for Paper, Board, Pulp Handsheets, and Related Products.” 6. Procedure 6.1 Clamp specimen uni
26、formly so that no slippage is visible during or after test. On units with automatic clamping devices, a minimum clamping pressure of 690 kPa (100 psi) is recommended. For linerboard with bursting strength above 2000 kPa (290 psi) a minimum clamping pressure of 1000 kPa (145 psi) is recommended to as
27、sure meeting the no-slip condition. Note that clamping pressure = gauge pressure (area of piston/area of clamp). See Appendix B for an example of this calculation. NOTE 1: Using excessive clamping pressures may lead to lower burst results mostly due to damage at the clamping site. If the recommended
28、 clamping pressure is insufficient to prevent slipping, perform additional testing to identify the lowest clamping pressure required to restrain the sample. 3 / Bursting strength of linerboard T 807 om-11 6.2 Apply the bursting pressure at the specified rate until the specimen ruptures. Record the m
29、aximum pressure registered by the gauge. Make an equal number of tests on each side of the sheet. This is very important because there is usually a significant difference between sides. 6.3 Make tests only in areas away from creases, imperfections, or visible damage. Position the specimen so that th
30、e clamped area is completely covered by the platens and the specimen extends beyond the clamped area. After each test, gently return the indicator needle of the gauge or digital readout to zero. 7. Report 7.1 Report as test result, in kilopascals (pounds per square inch), to the nearest gauge divisi
31、on. NOTE 2: In some countries, other classical unit systems are in use (Kg/cm2, bar, etc.). One may report values in these other systems in addition to the forms above if it would be particularly useful to the report recipient. 7.2 For each test unit report: 7.2.1 Average of 10 test determinations,
32、five from each side (if desired average from each side can be reported). 7.2.2 Maximum and minimum values and/or, 7.2.3 Standard deviation, 7.2.4 Number of test determinations made. 8. Safety precautions 8.1 Safety issues include the use of box cutters and paper cutters used to prepare samples. It i
33、s recommended that cut proof gloves be used any time a box cutter is being manipulated. 8.2 The burst tester upper platen comes down to secure the specimen creating a potential nip (pinch) point. Care should be taken on unguarded older units. Ensure that newer units always have properly functioning
34、guards. 8.3 The internal pressurizing fluid may be released with significant force if a diaphragm or rupture disc fails. Goggles are recommended when using an unshielded machine to protect the eyes from such hydraulic fluid discharges. 9. Precision 9.1 Repeatability (within a laboratory) = 9% Reprod
35、ucibility (between laboratories) = 13% Repeatability and reproducibility are estimates of the maximum difference (at 95% confidence) that should be expected when comparing test results for materials similar to those described below under similar test conditions. These estimates may not be valid for
36、different materials and testing conditions. 9.2 The estimates of repeatability and reproducibility are based on results from the Containerboard Interlaboratory Program conducted by CTS. The testing was conducted in 2010 using the om-08 version of the method. Testing was conducted on 3 linerboard wei
37、ghts: 35lbs. (171 g/m2), 42lb (205 g/m2), and 69 lb (337 g/m2). Laboratories made 10 determinations on 5 specimens for each test result. The estimates in the chart below are based on 16 results per laboratory for 42 lb linerboard and 8 results per laboratory for 35 lb and 69 lb linerboard. Between 4
38、6 and 52 laboratories are included in the calculations for each sample. Linerboard weight Average Repeatability r and %r Reproducibility R and %R Test results included Labs included 35 lb 92 8.2 9.0% 11.4 12.4% 8 48 42 lb 107 8.8 8.2% 14.4 13.5% 16 48 69 lb. 163 16.4 10.1% 20.9 12.8% 8 48 Results li
39、sted in pounds per square inch T 807 om-11 Bursting strength of linerboard / 4 10. Keywords Linerboards, Burst strength 11. Additional Information 11.1 Effective date of issue: May 1, 2011 11.2 Changes in the 2008 version include the addition of Appendix B and the safety precautions, plus some addit
40、ional revisions to improve the scope and summary in order to explain how this method differs from other burst strength methods. Also, corrections to conversions and minor editorial were incorporated. 11.3 Changes in the 2011 version include an updating of the precision statement, clarification of th
41、e allowance of other hydraulic fluids beyond glycerin, and an addition of section A2 regarding the use of foils to check the instrument. 11.3.1 The estimates of repeatability and reproducibility presented above differ from those published in previous revisions of the method (repeatability 6.4% and r
42、eproducibility 10.6%). The revised estimates are based on more recent testing in the same interlaboratory program. The increase of the precision estimates reflects larger variation within the more recent data. Appendix A. A.1 Calibration of apparatus for the original instrument design using Bourdon
43、gauges and a demountable clamping tripod (1, 2) NOTE 2: Some newer instruments may require slight modifications to the following procedures. A.1.1 Platens. The condition of the platens may be checked as follows: Place a sheet of filter paper over the lower platen and a sheet of pencil carbon paper f
44、ace down on the filter paper. Hold the upper platen so that it does not rotate while the clamping pressure is applied. When the clamp is raised and the paper is removed, a print of the platen contact will be found on the paper. Rotate the clamp through 90 and repeat the operation. If the platens are
45、 in good condition, a uniform print of the entire platen surface will be obtained. A.1.1.1 Frequently, it will be found that the lower platen has been strained so that only the central portion will print. If this occurs, replace the lower platen. If the print is heavy on one side, the platens are no
46、t parallel. This may be remedied by loosening the Allen setscrew in the center of the yoke assembly, which contacts the cylinder, rotating the cylinder in the proper direction and relocking the setscrew. In some cases, it may be necessary to loosen the cylinder nut so that the cylinder can be rotate
47、d. A.1.1.2 Check the lateral alignment of the platens when clamped together to make certain that the holes in the two platens are concentric. If the holes are not concentric, add shims between the cylinder and the yoke assembly or reduce the seat to move the chamber with respect to the frame. A.1.2
48、Diaphragms. When diaphragms on instruments using the disk-shaped diaphragms are to be changed, make sure that the control lever has been thrown into reverse and has returned automatically to neutral. Turn down the clamping wheel tightly to enable an easier removal of the diaphragm nut with the speci
49、al spanner wrench. When the diaphragm ring has been completely unscrewed, raise the clamp and remove the demountable tripod. The ring nut and lower platen may then be removed easily. Before inserting a new diaphragm, fill the chamber with air-free hydraulic fluid to the top of the saucer-like depression so that it is even with the clamping ridges. Keep these ridges clean and dry to minimize capillary leakage past them, and if any hydraulic fluid is spilled, wash the ridges with alcohol and wipe them dry. Carefully place the new
