1、Designation: D4226 16 An American National StandardStandard Test Methods forImpact Resistance of Rigid Poly(Vinyl Chloride) (PVC)Building Products1This standard is issued under the fixed designation D4226; the number immediately following the designation indicates the year oforiginal adoption or, in
2、 the case of revision, the year of last revision. 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 These test methods cover the determination of theenergy required to crack or break
3、 rigid poly(vinyl chloride)(PVC) plastic sheeting and profile flat sections used in buildingproducts, as well as extruded or molded test samples, underspecified conditions of impact from a freefalling standardweight striking an impactor with either of two configurations incontact with the specimen.1
4、.2 Two test procedures are included:1.2.1 Procedure A, used to determine minimum impactenergy required to cause failure (hole, crack, split, shatter, ortear).1.2.2 Procedure B, used to determine minimum impactenergy required to cause brittle failure.1.3 The values stated in inch-pound units are to b
5、e regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.NOTE 1There is no known ISO equivalent to this standard.1.4 The text of this standard references notes and footnoteswhich provide expla
6、natory material. These notes and footnotes(excluding, those in tables in figures) shall not be considered asrequirements of this standard.1.5 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
7、establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. Specific precau-tionary statements are given in Section 8.2. Referenced Documents2.1 ASTM Standards:2D618 Practice for Conditioning Plastics for TestingD883 Terminology Relatin
8、g to PlasticsD3679 Specification for Rigid Poly(Vinyl Chloride) (PVC)SidingD5947 Test Methods for Physical Dimensions of SolidPlastics SpecimensE178 Practice for Dealing With Outlying Observations3. Terminology3.1 DefinitionsDefinitions are in accordance with Termi-nology D883, unless otherwise indi
9、cated.3.2 Definitions of Terms Specific to This Standard:3.2.1 failure (of test specimen, as related to impactresistance)signified by the presence of a punched hole,crack, split, shatter, or tear that was created in the target area bythe impact of the falling weight (see Fig. 1).3.2.2 ductile failur
10、e (ductile break, as related to impactresistance) a tear or split having an angle greater than 0 atthe tip and extending through the entire thickness of thespecimen such that light is directly visible through the tear orsplit (see Fig. 1).3.2.3 brittle failure (brittle break, as related to impactres
11、istance) a punched hole, split, or shatter where a piece ofthe specimen separates from the main part of the specimen ora crack that has a 0 angle at the tip as viewed by the naked eye(see Fig. 1).3.2.4 mean failure height (Procedure A)the height fromwhich the falling weight will cause 50 % of the sp
12、ecimens tofail.1These test methods are under the jurisdiction of ASTM Committee D20 onPlastics and are the direct responsibility of Subcommittee D20.24 on PlasticBuilding Products.Current edition approved May 1, 2016. Published May 2016. Originallyapproved in 1983. Last previous edition approved in
13、2011 as D4226 - 11. DOI:10.1520/D4226-16.2For 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 to the standards Document Summary page onthe ASTM website.*A Summary of Change
14、s section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2.5 mean failure energy (mean impact resistance), ( Pro-cedure A)energy required to produce 50 % failures; theproduct of the weight and mea
15、n failure height.3.2.6 normalized mean failure energy (normalized meanimpact resistance) the mean failure energy per unit (average)specimen thickness (Procedure A).3.2.7 mean brittle failure heightthe height from which thefalling weight will cause 50 % brittle failures in specimens(Procedure B).3.2.
16、8 mean brittle failure energy (mean energy of ductile-to-brittle transition), (Procedure B)energy required to pro-duce 50 % brittle failures; the product of the weight and meanbrittle failure height.3.2.9 normalized mean brittle failure energy (normalizedmean energy of ductile-to-brittle transition)
17、, (Procedure B)the mean brittle failure energy per unit (average) specimenthickness.3.2.10 outlieran observation that appears to deviate mark-edly from other members of the sample in which it occurs.4. Summary of Test Method4.1 The building product profile is cut apart, if necessary, toobtain a flat
18、 specimen at least 0.75 in. (19 mm) wide.4.2 Procedure A establishes the height from which a stan-dard falling 8-lb (3.6-kg) weight will cause 50 % of thespecimens to fail.4.3 Procedure B establishes the height from which a stan-dard falling 8-lb (3.6-kg) weight will cause 50 % of thespecimens to fa
19、il in a brittle mode.4.4 Both procedures employ either of two configurations ofimpactor heads resting on the specimen. The specimen lays ona stand that has a 0.64-in. (16.3-mm) hole. The falling weightimpacts on the impactor head tending to drive it through thespecimen into the hole of the stand.FIG
20、. 1 Types of Failures of the SpecimenD4226 1624.5 The technique used to find 50 % failure level in bothprocedures is commonly called the Bruceton Staircase Methodor Up-and-Down Method. Testing is concentrated near themean, reducing the number of specimens required to obtain areasonably precise estim
21、ate.5. Significance and Use5.1 The impact strength values obtained on the flat sectionsof a building product profile are relevant only to the flat sectionthat has been tested and these values do not necessarily indicatethe impact resistance of the whole product, which is affected bythe configuration
22、 of the profile (that is, corners, ribs, etc).5.2 Constant weight and variable height, employed in thesetest methods, allow the velocity of impact to vary and,therefore, by Procedure B, can determine the energy ofductile-to-brittle transition, which cannot be determined if avariable weight is droppe
23、d from a constant height.5.3 These test procedures have been found to be usefulelements in rigid poly(vinyl chloride) (PVC) building productcharacterization. Compound qualification, finished productquality control, environmental and weatherability research anddevelopment studies, and fabrication tol
24、erance prediction con-stitute useful applications.5.4 Choice of the specific impactor head configuration usedis related to a variety of product attributes, such as specimenthickness and product toughness as well as abstract factors,such as the anticipated mode of failure in a specific application.Th
25、e geometric uniqueness of the impactor head configurationsprevents any comparison or correlation of testing results onsamples tested with differing impactor head configurations. Ingeneral, the conical impactor, C.125, is useful to ensure failureof thicker specimens where the H.25 impactor caused nof
26、ailure.NOTE 2Equivalent surface conditions are more likely to occur whenspecimens are prepared by compression molding or extrusion than byinjection molding.5.5 When comparing different samples tested with the sameimpactor head configuration, impact resistance shall be permit-ted to be normalized for
27、 average specimen thickness over areasonably broad range (for example, 1 to 3 mm).3However,this should only be done when the surface conditions listed in6.1 are essentially equivalent.6. Interferences6.1 The results obtained are greatly influenced by thequality of the test specimens. Cracks usually
28、start at the surfacein tension; the surface opposite the one that is struck by theimpactor head. The composition of this surface layer and thedegree of orientation introduced during the formation of thespecimen are very important variables. Flaws in this surfacewill also affect results. Because of t
29、hese factors, sometimesadditional information about the sample is achieved by testing3O.R. Weaver, “Using Attributes to Measure a Continuous Variable in ImpactTesting Plastic Bottles,” Materials Research steel-rod impact weight weighing 8 6 0.2 lb (3.6 6 0.1 kg);hardened steel impactors as specified
30、 in 7.1.2; a slotted guidetube 40 in. (1.0 m) in length in which the impact weights slide,having an internal diameter sufficient so that friction does notreduce the weight velocity, and having graduations in inch-pound (newton-metre) increments, or multiples thereof. Abracket is used to hold the tub
31、e in a vertical position byattaching it to the base and also to hold the hand knob, whichis a pivot-arm alignment for the impactor, about 2 in. (50 mm)under the tube. The top edge of the opening in the specimensupport plate should be rounded to a 0.031-in. (0.8-mm) radius.Fig. 3 shows the specimen s
32、upport configuration for this test.7.1.1 The tester shall be mounted so that the axis of the tubeis plumb when measured with a spirit level at least 1 ft (300mm) in length.7.1.2 Impactor Configurations:7.1.2.1 Impactor C.125 shall be constructed, as is shown inFig. 4, of tough, hardened (Rockwell C5
33、0-55), scratch resistantsteel. It should have a conical (40-) configuration and 0.125-in. (3.18-mm) radius hemispherical tip.7.1.2.2 Impactor H.25 shall be constructed, as is shown inFig. 3, of tough, hardened (Rockwell C50-55) scratch resistantsteel. It should have a 0.25-in. (6.35-mm) radius hemis
34、phericaltip (see Fig. 3 and Fig. 4).7.1.2.3 The surface of the impactor head shall be polishedfree of nicks, scratches, or other surface irregularities.7.2 Supporting BaseIn order to minimize the energyabsorption, compression, and deflection of the support thetester shall be firmly fixed to a dense,
35、 solid, block or base.7.2.1 The main body of said block or base shall havemaximum dimensions of 16 in. (h) 30 in. (w) 30 in. (d) andshall have a minimum weight of 375 lb. This block shall beplaced at a height that facilitates equipment usage. It is notnecessary to bolt blocks or bases of this weight
36、 to the floor.NOTE 3The required block weight and dimensions conform tocommercially available butcher block type tables.7.2.2 Alternative supporting bases or those lighter than 375lb should be bolted to a concrete floor. Mean failure energycomparisons shall be made between these alternative supports
37、and one where the tester is bolted directly to the concrete floor.If mean failure energy differences between the concrete floorand the alternative support are found statisticallynonsignificant, use of the lighter support shall be allowed.7.2.3 If the weight of the butcher block that was originally37
38、5 lb or greater decreases with time to less than 375 lb,increase the block weight to a minimum of 375 lb by adding asuitable amount of weight to the bottom of the table. Theweight shall be tightly affixed and in direct contact with thebottom of the table and not cause any vibrations during theimpact
39、 test.NOTE 4The weight of the butcher block can decrease over time due,for instance to drying.7.2.4 Use of rubber mats either under the tester or thesupporting base is prohibited.7.3 Micrometer, for measurement of specimen thickness. Itshould be accurate to1%oftheaverage thickness ofspecimens used.
40、See Test Method D5947 for suitable microm-eters.8. Safety Precautions8.1 Shielding devices shall be provided to protect personnel.8.2 Atube can contain the impactor head if it rebounds afterstriking a specimen, or the impactor head may be drilled for acotterpin to prevent rebound. The cotterpin must
41、 be locatedwell above the penetration depth of the impactor head.FIG. 3 Impactor Head Configuration H.25 Specimen Support DetailD4226 1649. Sampling9.1 Sample in a statistically acceptable manner.The samplesshall be representative of the lot under study.10. Test Specimen10.1 Flat test specimens at l
42、east 0.75-in. (19-mm) wide arepermitted to be tested. The specimens shall be free of obviousimperfections unless they constitute variables under study.10.2 When the approximate mean failure height for a givensample is known, 20 specimens usually yield sufficientlyprecise results. If the mean failure
43、 height cannot beapproximated, six or more specimens shall be used to deter-mine the appropriate starting point of the test.NOTE 5Specimen quantity, as small as five, often yields sufficientlyreliable estimates of the mean failure height. However, the estimatedstandard deviation will be relatively l
44、arge.411. Conditioning11.1 Unless otherwise specified, condition the test speci-mens at 73.4 6 3.6F (23 6 2C) and 50 6 10 % relativehumidity for not less than 40 h prior to test in accordance withProcedure A of Methods D618. In cases of disagreement, thetolerance shall be 61.8F (61C) and 65 % relati
45、ve humidity.11.2 Quality Control TestsCondition the test specimens at73.4 6 3.6F (23 6 2C) for4hinair.12. Procedure12.1 Procedure A:12.1.1 When testing individual specimens or coupons, mea-sure and record the thickness of each specimen at the antici-pated area of impact. Average all values to determ
46、ine averagethickness. When using a single large specimen such as a stripof PVC siding, measure the thickness at five points uniformlydown the length of PVC siding under test. Use the average ofthese five values as the average thickness. The thickness of anyindividual measurement shall not vary by mo
47、re than 5 % fromthe average thickness.12.1.2 When testing individual specimens or coupons,choose randomly from the sample. Determine the order oftesting by using a set of random numbers.12.1.3 Select the proper impactor-head configuration (C.125or H.25) specified for the test and install on the appa
48、ratus.Adjust the guide arm so that each impactor head is visuallycentered and achieves the proper depth of penetration. Depth ofpenetration is the distance the impactor head protrudes into thesupport plate when properly seated. For the H.25 tup this shall4Brownless, K. A., Hodges J. L., Jr., and Ros
49、enblatt, Murray, “The Up-and-Down Method with Small Samples,” American Statistical Association Journal,JSTNA, Vol. 48, 1953, pp. 262-277.FIG. 4 Impactor Head Configuration C.125D4226 165be 0.48 in 6 0.04 in. (1.22 cm 6 0.10 cm) (Fig. 3) and 0.69in.6 0.04in. (1.75 cm 6 0.10 cm) for the C.125 tup (Fig. 4).NOTE 6Centering of Tup- Periodic visual inspection during testingensures tup is centered.12.1.4 After raising the weight and impactor foot, place thespecimen between the mandrel and the anvil making sure thatit lies flat and covers the anvil. The cla
