ANSI TAPPI T494 OM-2013 Tensile properties of paper and paperboard (using constant rate of elongation apparatus).pdf

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1、TAPPI/ANSI T 494 om-13 SUGGESTED METHOD 1964 OFFICIAL STANDARD 1970 OFFICIAL TEST METHOD 1981 CORRECTED 1982 REVISED 1988 REVISED 1996 REVISED 2001 REVISED 2006 REVISED 2013 2013 TAPPI The information and data contained in this document were prepared by a technical committee of the Association. The

2、committee and 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

3、published. Approved 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 relat

4、ed to such use. 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 ch

5、emicals which 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 haza

6、rdous chemicals. 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

7、 and disposal of these chemicals. Tensile properties of paper and paperboard (using constant rate of elongation apparatus) 1. Scope 1.1 This test method describes the procedure, using constant-rate-of-elongation equipment, for determining four tensile breaking properties of paper and paperboard: ten

8、sile strength, stretch, tensile energy absorption, and tensile stiffness. 1.2 This procedure is applicable to all types of paper and paperboard within the limitations of the instruments used, whether the instruments perform horizontal or vertical tests or whether they are manually operated or comput

9、er controlled. It is also applicable to handsheets, with modifications, as specified in TAPPI T 220 “Physical Testing of Pulp Handsheets.” It does not apply to combined corrugated board. 2. Definitions 2.1 Tensile strength, the maximum tensile force developed in a test specimen before rupture on a t

10、ensile test carried to rupture under prescribed conditions. Tensile strength (as used here) is the force per unit width of test specimen. 2.2 Stretch, the maximum tensile strain developed in the test specimen before rupture in a tensile test carried to rupture under prescribed conditions. The stretc

11、h (or percentage elongation) is expressed as a percentage, i.e., one hundred times the ratio of the increase in length of the test specimen to the original test span. 2.3 Tensile energy absorption (TEA), the work done when a specimen is stressed to rupture in tension under prescribed conditions as m

12、easured by the integral of the tensile strength over the range of tensile strain from zero to maximum strain. The TEA is expressed as energy per unit area (test span width) of test specimen. 2.4 Tensile stiffness, the ratio of tensile force per unit width to tensile strain within the elastic region

13、of the tensile-strain relationship. The elastic region of the tensile-strain relationship is the linear portion of the load-elongation relationship up to the elastic limit. The elastic limit is the maximum tensile force above which the load-elongation T 494 om-13 Tensile properties of paper and pape

14、rboard / 2 (using constant rate of elongation apparatus) relationship departs from linearity. (Tensile stiffness is numerically equivalent to E t, where E is the modulus of elasticity and t is sample thickness.) 2.5 Breaking length, the calculated limiting length of a strip of uniform width, beyond

15、which, if such a strip were suspended by one end, it would break of its own weight. 2.6 Tensile index, the tensile strength in N/m divided by grammage. NOTE 1: ISO/TC6 recommends the use of tensile index over breaking length. See TAPPI T 1210 or TIP 0800-01 “Units of Measurement and Conversion Facto

16、rs.” 3. Significance 3.1 Tensile strength is indicative of the strength derived from factors such as fiber strength, fiber length, and bonding. It may be used to deduce information about these factors, especially when used as a tensile strength index. For quality control purposes, tensile strength h

17、as been used as an indication of the serviceability of many papers which are subjected to a simple and direct tensile stress. Tensile strength can also be used as an indication of the potential resistance to web breaking of papers such as printing papers during printing on a web fed press or other w

18、eb fed converting operations. When evaluating the tensile strength, the stretch and the tensile energy absorption for these parameters can be of equal or greater importance in predicting the performance of paper, especially when that paper is subjected to an uneven stress such as gummed tape, or a d

19、ynamic stress such as when a sack full of granular material is dropped. 3.2 Stretch (sometimes evaluated in conjunction with bending resistance) is indicative of the ability of paper to conform to a desired contour, or to survive nonuniform tensile stress. It should be considered important in all pa

20、pers, but is of particular importance in papers where stress-strain properties are being modified or controlled. This includes creped paper, pleated paper, air-dried paper, and paper that has been made extensible through mechanical compaction. Stretch is evaluated in decorative papers and certain in

21、dustrial grades such as paper tapes and packaging papers, both as an index of how well the paper will conform to irregular shapes and, along with tensile energy absorption, as an indication of the papers performance under conditions of either dynamic or repetitive straining and stressing. Stretch ha

22、s also been found important in reducing the frequency of breaks on high-speed web fed printing presses such as are used to print newspapers. 3.3 Tensile energy absorption is a measure of the ability of a paper to absorb energy (at the strain rate of the test instrument), and indicates the durability

23、 of paper when subjected to either a repetitive or dynamic stressing or straining. Tensile energy absorption expresses the “toughness” of the sheet. An example of this is a multi-wall sack that is subject to frequent dropping. In packaging applications such as multi-wall sacks, favorable drop tests

24、and low failure rates have been found to correlate better with tensile energy absorption than with tensile strength. 3.4 Tensile stiffness tells of the stiffness of the sheet and often gives a better indication of the mechanical response of the sheet to converting forces than does failure criteria.

25、4. Apparatus 4.1 Tensile testing machine1, a constant-rate-of-elongation type, meeting the following requirements: 4.1.1 Two clamping jaws, each with a line contact for gripping the specimen, with the line contact perpendicular to the direction of the applied load and with means for controlling and

26、adjusting the clamping pressure. NOTE 2: “Line contact” describes the clamping zone resulting from gripping the specimen between a cylindrical and a flat surface or between two cylindrical surfaces whose axes are parallel (1). NOTE 3: For certain grades of paper “line contact” jaws may not be approp

27、riate and it may be necessary to substitute flat gripping surfaces. Certain grades are damaged by the “line contact” loading between cylindrical and flat surfaces. The use of emery cloth on flat gripping surfaces will help minimize slippage for some board grades. 4.1.2 The clamping surfaces of the t

28、wo jaws shall be in the same plane and so aligned that they hold the test specimen in that plane throughout the test. The clamping lines shall be parallel to each other within an angle of 1, and 1Names of suppliers of testing equipment and materials for this method may be found on the Test Equipment

29、 Suppliers list, available as part of the CD or printed set of Standards, or on the TAPPI website general Standards page. 3 / Tensile properties of paper and paperboard T 494 om-13 (using constant rate of elongation apparatus) shall not change more than 0.5 during the test. The applied tensile force

30、 shall be perpendicular to the clamp lines within 1 throughout the test. 4.1.3 The distance between line contacts at the start of the test shall be adjustable and resettable to 0.5 mm (nominally 0.02 in.) for the specified initial test span (6.4). (See 11.3.) 4.1.4 The rate of separation of jaws sha

31、ll be 25 5 mm/min (nominally 1.0 in. /min), or as otherwise noted (6.5) and once set shall be resettable and constant to 4%. (See 11.3.) 4.1.5 Recorder or indicator capable or indicating the actual force on the specimen within 1% or 0.1 N, whichever is greater. 4.1.6 Recorder speed or indicator shal

32、l be adjustable to provide a readability and accuracy of 0.05% stretch. 4.2 Alignment jig (optional) (1) to facilitate centering and aligning the specimen in the jaws, so that the clamping lines of contact are perpendicular to the direction of the applied force and the center line (long dimension) o

33、f the specimen coincides with the direction of applied force. 4.3 Planimeter or integrator, respectively, to measure the area beneath the load-elongation curve or to compute directly the work to rupture, with an accuracy of 1%. 4.4 Specimen cutter, for cutting specimens of the required width, with s

34、traight parallel sides (5.3). NOTE 4: Fully automated laboratory management and/or data acquisition systems are available which perform several functions such as: automatic calibration check, pre-setting and storing a variety of test programs, cutting the test strip, acquiring test data, and accurat

35、ely determining the tensile breaking properties of paper and paperboard. These tests may be performed with the test strip horizontal or vertical by such equipment. Such equipment may be suitable for use in performing this method; however, the user is responsible for making independent assessment of

36、this fact on the basis of data generated using specific equipment. 5. Sampling and test specimens 5.1 For sampling for acceptance of a lot of paper, paperboard, related product, without prior agreement between buyer and seller, use TAPPI T 400 “Sampling and Accepting a Single Lot of Paper, Paperboar

37、d, Containerboard, or Related Product.” 5.2 For sampling for quality control and other purposes, use accepted and agreed upon company and laboratory sampling practices. 5.3 Precondition, then condition, the sample in accordance with TAPPI T 402 “Standard Conditioning and Testing Atmospheres for Pape

38、r, Board, Pulp Handsheets, and Related Products” prior to cutting the specimens. NOTE 5: The exposure of the paper to a high relative humidity before preconditioning and conditioning can lead to erratic results varying from a decrease in stretch and tensile to a substantial increase (30% increase in

39、 stretch not uncommon) in these properties. Consequently, TEA is similarly affected. Careful protection of the sample from the time of sampling until testing is therefore very important. 5.4 Cut 10 test specimens from each test unit of the sample in each principal direction of the paper 25 1 mm (nom

40、inally 1.0 in.) wide with sides parallel within 0.1 mm (nominally 0.004 in.) and long enough to be clamped in the jaws when the test span is 180 5 mm (nominally 7.0 in.), leaving enough length so that any slack can be removed from the strip before clamping. (See 11.3.) Insure that strips are free fr

41、om abnormalities, creases, or wrinkles. In some cases, it may be impossible or impractical to obtain a test specimen having a length long enough to be clamped in the jaws having the test span specified here. In such cases, see Appendix A.3.1 for special considerations and procedures required for tes

42、ting samples at smaller test spans. 6. Procedures 6.1 Perform the test in the testing atmosphere specified in T 402. 6.2 If the test specimen width is not known to 0.1 mm (nominally 0.004 in.) (i.e., if a previously evaluated precision cutter is not used), determine width and parallelism using magni

43、fier and scale. Lack of parallelism is indicated by a difference in width of the two ends of the specimen. 6.3 The testing machine shall be calibrated and adjusted as described in Appendixes A.1 and A.2. 6.4 Set the clamps to an initial test span (distance between line contacts) of 180 5 mm (nominal

44、ly 7.0 in.). Determine and always reset this distance within 0.5 mm (nominally 0.02 in.). (See Appendix A.1.3.) 6.5 Set the controls for rate of separation of the jaws to 25 5 mm/min (nominally 1.0 in./min). (See 11.3.) In cases where the time required to break a single strip exceeds 30 s, a more ra

45、pid rate of jaw separation shall be used, T 494 om-13 Tensile properties of paper and paperboard / 4 (using constant rate of elongation apparatus) such that the time to break a single strip will be between 15 and 30 s. In such cases, the speed of the instrument must be reported, along with the test

46、data. NOTE 6: For purposes of determining shipping sack and shipping sack paper TEA compliance with Carrier and Federal requirements, Uniform Freight Classification Rule 40, National Motor Freight Classification, Item 200, UUS 48 and Department of Transportation 178.236, 4.8 in. (122 mm) between the

47、 jaws and 1 in. (25 mm) per minute jaw separation should be used. NOTE 7: If, for any reason, any of the testing conditions specified above (specimen length, rate of jaw separation, sample width, etc.) cannot be followed because of the small sample size or other reason, the method variance must be s

48、tated in the report. 6.6 Align and clamp the specimen first in one jaw and then, after carefully removing any noticeable slack, but without straining the specimen, in the second jaw. While handling the test specimen, avoid touching the test area between the jaws with the fingers. Use a clamping pres

49、sure determined to be satisfactory (Appendix A.1.4), i.e., so that neither slippage nor damage to the specimen occurs. Automated instruments for which both jaws close simultaneously are within the context of this method. 6.7 Test 10 specimens in each principal direction for each test unit. 6.8 Reject any value in which the test specimen slips in the jaws, breaks within the clamping area, or shows evidence of uneven stretching across its width. Also reject any values for test specimens which break within 5 mm of