ASTM D2343-2008 Standard Test Method for Tensile Properties of Glass Fiber Strands Yarns and Rovings Used in Reinforced Plastics.pdf

1、Designation: D 2343 08Standard Test Method forTensile Properties of Glass Fiber Strands, Yarns, andRovings Used in Reinforced Plastics1This standard is issued under the fixed designation D 2343; the number immediately following the designation indicates the year oforiginal adoption or, in the case o

2、f revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope*1.1 This test m

3、ethod covers the determination of the com-parative tensile properties of glass fiber strands, yarns, androvings in the form of impregnated rod test specimens whentested under defined conditions of pretreatment, temperature,humidity, and tension testing machine speed. This test methodis applicable to

4、 continuous filament, glass fiber materials thathave been coated with a resin compatible sizing. This methodis intended for use in quality control and R or the ends shall be sanded with 240 gritsandpaper or fine emery cloth and tested using rubber facedgrips.5. Significance and Use5.1 Tensile proper

5、ties determined by this test method are ofvalue for identifying and characterizing materials for control1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.18 on Reinforced Thermoset-ting Plastics.Current edition approved

6、March 1, 2008. Published March 2008. Originallyapproved in 1965. Last previous edition approved in 2003 as D2343 - 03.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer t

7、o the standards Document Summary page onthe ASTM website.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.and specification purposes as well as for providing data forre

8、search and development studies.5.2 This test method is intended for use in testing resin-compatible sized glass fiber materials that have been designedspecifically for use with certain generic types of plastics. Theuse of a resin impregnant that is compatible with the reinforce-ment material under t

9、est produces results that are most repre-sentative of the actual strength that is available in the materialwhen used as intended in an end item. Premature reinforcementfailure may occur if the elongation of the resin system is lessthan that of the reinforcement being tested. This requirementmay rest

10、rict the use of certain resin systems in this procedure.Misleading results may be obtained when glass fiber materialsare tested without complete resin impregnation of the fiber orwhen a non-compatible resin is used for impregnation.5.3 This test method is useful for testing pretreated speci-mens for

11、 which comparative results are desired. Values ob-tained by this test method may be affected by gage length,gripping system, testing speed, and the resin impregnation ratioof the specimen.6. Apparatus6.1 Impregnation ApparatusAn example of an acceptableimpregnation apparatus for strands is shown in

12、Fig. 1. Minormodifications to the apparatus are acceptable providing con-sistent samples are produced. The apparatus shall consistessentially of the following:6.1.1 Free Wheeling Spindle (Optional)A freely turningspindle with a horizontal axis for holding the yarn spool orroving ball. A spindle allo

13、ws fiber to be pulled from a yarnbobbin or the outside of a roving package. Alternatively, thefiber may be drawn from the package without the spindle as inthe case of pulling from the interior of a roving package orforming cake.6.1.2 Tension Regulating System capable of maintaining theroving or yarn

14、 under tension between 0.2 Newtons and 20Newtons.6.1.3 Impregnation Tank, as illustrated in Fig. 2, consistingof a container and a static spreader bar assembly. The tank musthave the capability of maintaining the required resin tempera-ture within 65C. This may be accomplished by use of adouble wall

15、ed vat, with heating fluid circulating between thewalls, or by use of an external heating plate.6.1.4 Die, as illustrated in Fig. 3, made of stainless steelwhich gives a defined circular cross-section to the impregnatedroving.6.1.5 Winding Device and Framefor collecting the im-pregnated roving which

16、 insures that the fibers are kept underconstant tension and places the strands onto the fixture in amanner which allows separate specimens to be fabricated.6.2 Template for Tabbing (Optional)Atemplate, as shownin Fig. 4, shall be used to provide proper positioning of endtabs.6.3 Tension Testing Mach

17、ineA testing machine having aconstant-rate-of-crosshead movement and comprising essen-tially the following shall be available:6.3.1 Stationary Member, with one grip.6.3.2 Movable Member, with a second grip.6.3.3 GripsGrips for holding the test specimen betweenthe fixed and the movable member shall b

18、e of the self-aligningtype (that is, they shall be attached to the fixed and movablemembers in such a manner that they will move freely intoalignment as soon as any load is applied). The long axis of thetest specimens will then coincide with the direction of theapplied pull through the center line o

19、f the grip assembly.NOTE 4Air-actuated grips have been found advantageous and arerecommended for use in this test method.1 Die 5 Moving Support2 Tensioning Bars 6 Impregnation Vat (temperature regulated)3 Resin Level 7 Glass Input4 Tensioning DeviceFIG. 1 Typical Impregnation Equipment Configuration

20、D2343082NOTE 5Rubber with a ShoreAhardness of 91 has been found to workwell as a grip surface.NOTE 6Recommended starting gripping pressures are 80 bars forspecimens with no tabs, 60 bars for specimens with cardboard tabs, and 40bars for composite tabs. These may be adjusted as necessary to preventsl

21、ippage providing damage to the specimen due to crushing is prevented.6.3.4 JawsA set of removable jaws to match the requiredgrips shall be used for clamping the test specimens. One of thefaces of the jaws shall be adjustable to compensate forthickness of the specimen ends, so that the tension force

22、isaligned with the center of the jaw. Rubber-faced jaws, with agripping length of at least 50 mm, shall be used for grippingspecimens unless tabs are used. The jaws shall be wider thanthe test specimen and shall have a gripping length of at least 50mm. Their faces shall be plane and parallel and sha

23、ll ensureuniform pressure over the whole width of the test specimen toassure the specimen is held without slippage. If slippage of thetest specimens is observed, 240 grit sandpaper strips shall beused to improve gripping. The sandpaper should be replacedwhen it has lost its grittiness, or after ever

24、y 30 to 50 breaks.Alternatively, tabbing shall be used.6.3.5 Drive MechanismA drive mechanism capable ofimparting a uniform controllable speed to the movable memberof the apparatus.6.3.6 Load IndicatorA suitable load-indicating mecha-nism capable of showing the total tensile load carried by thetest

25、specimen when held by the grips shall be used. Thismechanism shall be essentially free of inertial lag at thespecified rate of testing and shall indicate the load with anaccuracy of at least 61 % of the indicated load value. Theaccuracy of the testing machine shall be verifiable in accor-dance with

26、Practices E4.6.3.7 Deflection-Measuring Device and RecorderA suit-able instrument for measuring deflection (extensometer) and asuitable mechanism for recording this deflection shall beprovided. It is desirable that this instrument and recorderautomatically record this deflection as a function of the

27、 load onthe test specimen. An extensometer gauge length of 50 mm isrecommended.6.4 Balance, Analytical.7. Test Specimens7.1 Test specimens shall consist of straight lengths ofimpregnated glass fiber strands, yarns, or roving. The lengthsshall be at least 250 mm.7.2 Effective Gage LengthThe distance

28、between the tabsor the distance between the rubber faced jaws shall be 150 mm.7.3 Number of SpecimensAt least five tension test speci-mens shall be tested for each ball or spool of glass fibermaterial for each property tested.7.4 Glass ContentThe glass content of the impregnatedglass samples shall b

29、e 70 6 5 % unless otherwise specified.8. Conditioning8.1 Strands, Yarns, and Rovings ConditioningThe glass fiber from which test specimens are to be preparedshall be kept in a room or enclosed space maintained at 23 62C (73.4 6 3.6F) and 50 6 5 % relative humidity inaccordance with Procedure A of Pr

30、actice D 618, except that 12h shall be the minimum conditioning time.8.2 Test Specimen ConditioningThe specimens shall beconditioned and tested in a room or enclosed space maintainedat atmospheric conditions of 23 6 2C (73.4 6 3.6F) and 501 Entrance Guide Eye 4 Breaker Bars2 Impregnating Vat 5 Exit

31、Tensioning Bar3 Glass Roving or Yarn 6 DieFIG. 2 Impregnation TankFIG. 3 Guide Pulley and Impregnation TankD23430836 5 % relative humidity in accordance with Procedure A ofPractice D 618, except that 16 h shall be the minimumconditioning time.9. Speed of Testing9.1 Speed of testing shall be the rela

32、tive rate of motion ofthe grips or test fixtures during test.9.2 The standard speed of testing is 10 mm/min for tensilestrength and 5 mm/min for apparent modulus of elasticityunless otherwise specified.10. Impregnation Procedure10.1 Set up the impregnating apparatus in accordance withFig. 1.10.2 Cov

33、er the ends of the winding fixture using 0.025 mm(0.001 in.) nominal thickness, heat-resistant plastic film, alu-minum foil, or equivalent parting film.10.3 Prepare a sufficient quantity of an impregnant suitablefor impregnating the material under test. Pour the impregnatingmixture into the tank so

34、that the level is about 10 mm (0.39 in.)above the static breaker bars (see Fig. 2).10.4 Immediately prior to threading the material through theimpregnation apparatus, cut a 1000 6 1-mm (40 6 0.04-in.)skein of the material under test. Repeat the procedure imme-diately after winding one set of specime

35、ns. Place the twoskeins in a muffle furnace maintained at a temperature that willgive complete burn-off (usually 450C for 2 h) . Remove thetwo skeins from the furnace and place in a desiccator for aminimum of 15 min. Weigh the two skeins to the nearest 0.001g and record as Weight X.10.5 Select a str

36、ipper die of the proper diameter by using thechart or calculations in 12.3.10.6 Thread the glass fiber material through the impregnat-ing apparatus in an “under, over, under” path through the staticspreader bars. Firmly attach the end of the glass fiber to thewinding fixture with heat-resistant mask

37、ing tape. Drape thematerial on the winding fixture. Rotate the fixture eithermanually or at a motorized rate not exceeding 8 m/min (26ft/min).10.6.1 Maintain an impregnant-to-glass weight ratio of70 % for the preparation of the test specimens (see Note 7).NOTE 7The choice of die and the tex of the f

38、iber will determine theglass content. It may also be affected by the viscosity of the resin used.Use the calculations in 12.2 to determine the die size to be used. If thecalculated die size does not yield the needed glass-weight ratio, thenadjustment of the die diameter will be needed.10.6.2 After t

39、he required number of specimens are wound,hold the winding tension on the material and use heat-resistantmasking tape to attach the material to the winding fixture. Cutthe material after attachment has been made.NOTE 8Optionally, a flat tongue depressor or metal spatula may beused to flatten the end

40、 100 mm (3.9 in.) of the glass strands. This flatteningof the gripped portion of the strands allows better clamping of thespecimens while minimizing crushing in the grip jaws.10.6.3 Place the loaded winding fixture in a horizontalposition in an air-circulating oven at a temperature and for alength o

41、f time necessary to cure the resin per manufacturersinstructions. After curing, cool to room temperature andremove the specimens from the winding fixture.10.7 Cut the specimens to the required length. Exercise careto prevent damage to the specimens during handling.10.8 Select specimens for the test

42、on the basis of theiruniformity and freedom from cuts, nicks, or other visible1 Notches for locations for impregnated rods 4 Dimension depending on number of specimens2 Position for strip of cardboard or mat 5 Thickness of cardboard or mat3 Border 6 StopsFIG. 4 Tabbing TemplateD2343084imperfections.

43、 Discard any unacceptable specimens. Weigheach specimen selected to the nearest 0.001 g and record asWeight Y.NOTE 9A thorough wetting of the glass fiber is essential to obtainingacceptable specimens. It is important that the specimens be examinedvisually to ensure that good wet-out of the fibers by

44、 the resin has occurred.If acceptable wet out is not obtained, it shall be necessary to adjust theconfiguration of the fibers through the breaker bars in the impregnationbath by changing the over under pattern. A note regarding the quality ofwet-out is required in the report.10.9 If tabbing is to be

45、 used, lay out the cut specimens onthe template and prepare a suitable quantity of adhesive (epoxyfor cardboard; polyester for mat). Place two strips of choppedstrand glass fiber mat (75 mm wide) or cardboard (55 mmwide) at their locations on the template on a metal plate andcoat them with adhesive.

46、 Place the test specimens and thenapply two additional strips of tabbing material. Place anothermetal plate on top of the tabs and specimens. Place thetemplate, tabs, specimens, and plate into an oven and cure thetab resin at the temperature and duration recommended by themanufacturer. Upon removal

47、from the oven, allow to cool andcut the tabbing to create individual tabbed test specimens. Takecare not to damage the impregnated glass specimens.11. Testing Procedure11.1 For testing tensile stress, set the speed of the testingmachine at 10 mm/minute.11.2 Adjust the load scale range so that it sha

48、ll be adequatefor the estimated breaking load of the specimen under test.11.3 Set the jaws at the effective gage length of 150 mm 62 mm apart. Place the specimen in the jaws, taking care toensure alignment of the specimen axis on the grips with animaginary line joining the points of the attachments

49、of the gripsto the machine. If mechanical grips are used, tighten the jawsevenly and firmly to the extent necessary to prevent slippage ofthe specimen during the test, but not to the point where thespecimen is crushed.11.4 Zero the machine and start the recorder. Load the testspecimen to failure. Record the ultimate breaking load.11.5 Compute the stress using the equation in 12.3.NOTE 10It is assumed for the purpose of this test that only the glassis involved in the rupturing process. This introduces a very slight error ,but simplifies the calculation.11.6