ASTM D6395-2011 7045 Standard Test Method for Flatwise Flexural Impact Resistance of Rigid Plastics《硬质塑料平面挠性冲击阻力标准试验方法》.pdf

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1、Designation: D6395 11Standard Test Method forFlatwise Flexural Impact Resistance of Rigid Plastics1This standard is issued under the fixed designation D6395; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision

2、. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 The resistance of plastics to breakage by flexural shockmay be determined by test methods such as those contained inTest Method D2

3、56. Specimens used in those test methodsfeature a milled notch to promote brittle fracture. The testspecimens are struck by a pendulum with the depth dimensionparallel to the direction of pendulum swing. This test method isdifferentiated from the others by its application to the assess-ment of the a

4、ffect on impact resistance of changes in thesurface of specimens resulting from weathering or otherexposure. In this test method, specimens are struck by apendulum with the depth dimension perpendicular to thedirection of pendulum swing. Test Method D5420 may also beused to conduct testing of weathe

5、red or exposed specimens.This test method is differentiated from Gardner Impact by thesmaller size of the specimens, which may result in substantiallyhigher productivity of accelerated weathering instruments.Additionally, this test method provides multiple data from asingle specimen for characteriza

6、tion of within specimen vari-ability.1.2 This test method describes the determination of theresistance of rigid plastic strip specimens to breakage orpermanent deformation when one end of the specimen issubjected to an impact upon its wide face while the other endof the specimen is firmly clamped.1.

7、3 This test method is applicable to specimens of 1.60 mm(0.0625 in.) thickness. However, the limits of applicability ofthe test are not sharply defined, and specimens having otherdimensions may frequently be used. For specimens of thick-nesses other than 1.60 mm (0.0625 in.) the ratio of the distanc

8、ebetween the top of the clamp and the centerline of the roundedstriking edge to the specimen thickness must be 2.5 6 0.1.1.4 This test method measures the relative impact resistanceof samples having approximately the same thickness. Normal-ization of the impact resistance to unit cross-sectional are

9、a onlypartly compensates for the effects of specimen thicknessvariation because, at the fixed cantilever length, the ratio ofshear stress to tensile stress in bending increases with thick-ness, and the importance of these effects in contributing to theenergy absorbed is greater for ductile than for

10、brittle failure.1.5 This test method is used primarily as a means ofassessing, for a series of samples, changes relative to a controldue to some treatment such as weathering or exposure to activeenvironments. It has been particularly useful as a sensitiveindicator of the development of surface crack

11、s or a brittlesurface. The existence or formation of cracks in an inherentlybrittle surface produces marked lowering of impact strengthwhen that surface is the one subjected to tension in the test.1.6 This test method is not generally applicable to materialssuch as elastomers or nonrigid plastics in

12、 which there is nofracture, permanent deformation, or other change due toyielding in flexure. However, it may be desirable to test suchmaterials as file samples to establish reference points when thetest is applied as described in 1.5.1.7 The values stated in SI units are to be regarded as thestanda

13、rd. The values given in parentheses are for informationonly.1.8 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-b

14、ility of regulatory limitations prior to use.NOTE 1There is no known ISO equivalent to this standard.2. Referenced Documents2.1 ASTM Standards:2D256 Test Methods for Determining the Izod PendulumImpact Resistance of PlasticsD618 Practice for Conditioning Plastics for TestingD883 Terminology Relating

15、 to PlasticsD5420 Test Method for Impact Resistance of Flat, RigidPlastic Specimen by Means of a Striker Impacted by aFalling Weight (Gardner Impact)D5947 Test Methods for Physical Dimensions of SolidPlastics Specimens1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand i

16、s the direct responsibility of Subcommittee D20.10 on Mechanical Properties.Current edition approved April 1, 2011. Published April 2011. Originallyapproved in 1999. Last previous edition approved in 2010 as D6395 - 10. DOI:10.1520/D6395-11.2For referenced ASTM standards, visit the ASTM website, www

17、.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to 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,

18、PO Box C700, West Conshohocken, PA 19428-2959, United States.3. Terminology3.1 Definitions used in this test method are in accordancewith Terminology D883.4. Significance and Use4.1 The flatwise flexural impact test is a test in which thekinetic energy lost by a moving pendulum during impact isused

19、to determine the energy to break or deform a testspecimen.4.2 The standard Izod test apparatus as described in TestMethod D256 is retrofitted with clamping jaws, which hold thetest specimen such that the flat face of the specimen is struckby the pendulum during a test.4.3 The pendulum shall be a sta

20、ndard Izod pendulum asdescribed in Test Method D256. It shall be capable of deliv-ering an energy of 2.71 6 0.14 J (2.00 6 0.10 ft.-lbf). Exceptas detailed in 10.5, this basic pendulum shall be used with allspecimens that extract less than 85 % of the available energy.Higher energy pendulums or a ba

21、sic pendulum to whichweights are added to increase its available energy shall be usedwith specimens that require more energy to break. A series ofenergy levels such that each has twice the energy of the nextlighter one will be found convenient. The striking nose of thependulum shall contact one of t

22、he flat faces of the specimen ata specified distance above the clamp edge. The ratio of thedistance between the top of the clamp and the centerline of therounded striking edge to the specimen thickness shall be 2.5 60.1.4.4 The type of failure of each specimen tested shall beassigned one of the foll

23、owing categories:Complete Break (C) A break in which the specimen isseparated into two or more pieces.Hinge Break (H)Anearly complete break in which there islittle or no spring back when the free end is bent or displaced.Partial Break (P)An incomplete break in which fractureextends through at least

24、50 % of the specimen thickness, andsuch that the free end can be bent with relatively little effort yethas considerable spring back.Nonbreak (N)A result where there is no fracture or thefracture extends less than 50 % of the specimen thickness.4.5 The value of this impact test is to determine the ch

25、angein impact properties that may result from a material havingbeen exposed to one or a series of environments, such asweathering at different intervals or different intensities whenthese data are compared to a file sample exposed only to thestandard laboratory environment or other agreed upon condi

26、-tions.4.6 The flatwise impact resistance is calculated as energyabsorbed per unit of cross-sectional area.4.7 Before proceeding with this test method, referenceshould be made to the specification of the material being tested.Any test specimen preparation, conditioning, dimensions,and/or testing par

27、ameters covered in the material specificationshall take precedence over those mentioned in this test methodexcept in cases where to do so would conflict with the purposefor conducting testing. If there are no material specifications,then the default conditions apply.5. Interferences5.1 Use of an imp

28、roper shim will result in test values eithertoo large or too small depending upon whether the shim in useis too short or too long.5.2 Orientation and molded-in stresses due to flow andcooling history result in variation in properties within injectionmolded specimen, especially at the ends and at the

29、 gate region.The effects of such variations can be minimized by avoidingtests close to the gate or the ends of the specimen.5.3 The clearance between the pendulum and the clamp asthe pendulum passes the clamp at its closest point during a testsignificantly affects the results of this test. If the sp

30、ecimenthickness is greater than about one half of the clearance, a largeenergy loss due to friction occurs in ductile specimens. Theratio of shear to surface tensile stress increases and the natureof failure may change abruptly over a narrow range ofspecimen thickness. The clearance is dictated by t

31、he ratio of thedistance between the pendulum nose centerline and the clamptop to the specimen thickness (2.5 6 0.1). The movable jawface and fixed jaw face set used for the thickness of specimenbeing tested shall either be of proper dimensions for this ratioor be adjustable in design to allow the ra

32、tio to be achieved.5.4 The use of excessive clamping force may inducestresses in test specimens causing variation in test results.6. Apparatus6.1 Testing MachineThe testing machine shall consist ofthe standard Izod test instrument as detailed in Test MethodD256 but with a modified clamping arrangeme

33、nt. Figs. 1-3illustrate typical clamping arrangements applicable to someinstruments. Other clamping arrangements may be used pro-vided that they maintain the specified ratio of the distancebetween the top of the clamp and the centerline of thependulum nose to the specimen thickness (2.5 6 0.1). Othe

34、rarrangements must also provide uniform clamping along theclamped length of the specimen and position the specimen suchthat when the pendulum is freely hanging, the striking edge iswithin 0.2 % of full scale of touching the front face of thespecimen as required by Test Method D256. As indicated byth

35、ese figures, the specimen clamp faces may be bolted orotherwise firmly attached to the existing Izod fixed andmovable jaws. To avoid compromising the instruments capa-bility for Izod testing, using either a dedicated set of fixed andmovable Izod jaws or clamping faces mounted in such a wayas to not

36、alter the existing Izod jaws is recommended.6.2 Specimen Clamp FacesSpecial clamp faces (see Fig.2) for both the fixed and the movable jaws of the clamp shallbe used to clamp the test specimen flatwise with its long axisvertical and its thickness direction parallel to the direction ofthe pendulum sw

37、ing. The clamp faces constitute a set. Somedimensions within the set are dictated by the thickness of thespecimen being tested and by the particular Izod instrumentbeing used. Fig. 2 provides the dimensions for clamp faceswhen used with one type of Izod instrument to test 1.60 mm(0.062 in.) thick sp

38、ecimen.6.2.1 For 1.60 mm (0.062 in.) thick specimens the distancebetween the upper edge of the clamp and the striking nose ofthe pendulum is 4.0 mm (0.161 in.) providing a clearanceD6395 112between the clamp and the lowest part of the pendulumsstriking nose of 3.20 mm (0.126 in.).NOTE 2The required

39、dimensions of hardware may vary from thoseprovided in the figures as a result of individual tolerances necessary tomate with preexisting components. The cumulative tolerances of indi-vidual hardware components must result in the required ratio of thedistance between the top of the clamp and the cent

40、erline of the roundedstriking edge to the specimen thickness of 2.5 6 0.1.6.3 ShimsAset of steel blocks (see Fig. 3) shall be used toprovide spacing between the lower end of the jaw faces to keepthe faces as parallel as possible during testing. A shim shall beselected to provide a spacing between th

41、e clamp faces matchedas closely as possible to the thickness of the specimen beingtested. In no case shall the shim protrude beyond the jaw faceby less than the specimen thickness or insufficient clamping ofthe specimen may result. Fig. 3 provides the dimensions for aset of shims spanning a typical

42、range of thickness for thetesting of 1.60 mm (0.0625 in.) thick specimen.6.4 MicrometersSuitable micrometers with a resolution of0.025 mm (0.001 in.) or better shall be used to measure thethickness of the test specimen. The micrometer shall conformto the applicable provisions of Test Method D5947.7.

43、 Sampling, Test Specimen, and Test Units7.1 The standard test specimen shall have a rectangularcross-section and an approximate length of 65 mm (2.5 in.).Most specimens should be 12.7 mm (0.500 in.) wide by 1.60mm (0.0625 in.) thick, but for some materials, such as thosewhich are glass reinforced, i

44、t may be desirable to use speci-mens of other thicknesses. The specimens may be molded orcut from flat sheet, but they shall be of uniform dimensionswithin any given set.7.2 Trim or sand off any protrusions that might interferewith clamping or positioning the specimen in the instrumentclamps. Do not

45、 introduce notches or scratches in the test faceof the specimen.7.3 Injection-molded specimens shall have at least 6 mm(0.25 in.) cut from the end to be tested first so that when thespecimen is clamped in the testing machine, the clamp edgewill be no less than 12 mm (0.5 in.) from the original end o

46、f thespecimen. The clamp edge shall also be at least 6 mm (0.25 in.)from a gate. Whenever this test is used for assessing agingeffects, cut off any portion of the test specimen end which hasnot been uniformly exposed to the aging environment so thatthe edge of the clamp will be at least 6 mm (0.25 i

47、n.) from theunexposed region.8. Calibration and Standardization8.1 Check the flatwise impact tester periodically for con-formance to the provisions of Test Method D256.8.2 The proper movable jaw face, fixed jaw face, and shimshall be installed for the thickness of the specimen being tested.The dimen

48、sional relationships between the various combina-tions of hardware components for a 1.60 mm (0.0625 in.) thickspecimen is provided in Fig. 1.8.3 The clearance between the pendulum and the upper gripsurface at their closest point shall be checked frequently toconfirm that the correct clearance is bei

49、ng used for thethickness of the specimen being tested and that the clearanceplus striker radius meets the required ratio.8.4 Adequate file samples for each group of treated samplesshall be tested, preferably at the same time that the treatedsamples are tested.9. Conditioning9.1 ConditioningCondition the test specimens at 23 62C (73.4 6 3.6F) and 50 6 10 % relative humidity for notless than 40 h prior to test in accordance with Procedure A ofPractice D618, unless otherwise specified by contract orrelevant material specification, or unless it has been shown thatconditioni