ASTM D395-2018 Standard Test Methods for Rubber Property&x2014 Compression Set.pdf

1、Designation: D395 18Standard Test Methods forRubber PropertyCompression Set1This standard is issued under the fixed designation D395; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parenthese

2、s indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope1.1 These test methods cover the testing of rubber intendedfor use in app

3、lications in which the rubber will be subjected tocompressive stresses in air or liquid media. They are applicableparticularly to the rubber used in machinery mountings, vibra-tion dampers, and seals. Three test methods are covered asfollows:Test Method SectionACompression Set Under Constant Force i

4、n Air 811BCompression Set Under Constant Deflection in Air 1215CCompression Set Under Constant Deflection in AirConsidering Material Hardness16211.2 The choice of test method is optional, but considerationshould be given to the nature of the service for whichcorrelation of test results may be sought

5、. Unless otherwisestated in a detailed specification, Test Method B shall be used.1.3 Test Method B is not suitable for vulcanizates harderthan 90 IRHD.1.4 The values stated in SI units are to be regarded as thestandard.1.5 This standard does not purport to address all of thesafety concerns, if any,

6、 associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.6 This international standard was developed in accor-dance with international

7、ly recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D1349 Practic

8、e for RubberStandard Conditions for Test-ingD3182 Practice for RubberMaterials, Equipment, and Pro-cedures for Mixing Standard Compounds and PreparingStandard Vulcanized SheetsD3183 Practice for RubberPreparation of Pieces for TestPurposes from ProductsD3767 Practice for RubberMeasurement of Dimensi

9、onsD4483 Practice for Evaluating Precision for Test MethodStandards in the Rubber and Carbon Black ManufacturingIndustriesE145 Specification for Gravity-Convection and Forced-Ventilation Ovens3. Summary of Test Methods3.1 A test specimen is compressed to either a deflection orby a specified force an

10、d maintained under this condition for aspecified time and at a specified temperature.3.2 The residual deformation of a test specimen is measured30 min after removal from a suitable compression device inwhich the specimen had been subjected for a definite time tocompressive deformation under specifie

11、d conditions.3.3 After the measurement of the residual deformation, thecompression set, as specified in the appropriate test method, iscalculated according to Eq 1 and Eq 2.4. Significance and Use4.1 Compression set tests are intended to measure the abilityof rubber compounds to retain elastic prope

12、rties after pro-longed action of compressive stresses. The actual stressingservice may involve the maintenance of a definite deflection,the constant application of a known force, or the rapidly1These test methods are under the jurisdiction of ASTM Committee D11 onRubber and Rubber-like Materials and

13、 are the direct responsibility of SubcommitteeD11.10 on Physical Testing.Current edition approved July 1, 2018. Published September 2018. Originallyapproved in 1934. Last previous edition approved in 2016 as D395 161. DOI:10.1520/D0395-18.2For referenced ASTM standards, visit the ASTM website, www.a

14、stm.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.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis inte

15、rnational standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Co

16、mmittee.1repeated deformation and recovery resulting from intermittentcompressive forces. Though the latter dynamic stressing, likethe others, produces compression set, its effects as a whole aresimulated more closely by compression flexing or hysteresistests. Therefore, compression set tests are co

17、nsidered to bemainly applicable to service conditions involving staticstresses. Tests are frequently conducted at elevated tempera-tures.5. Test Specimens5.1 Specimens from each sample may be tested in duplicate(Option 1) or triplicate (Option 2). The compression set of thesample in Option 1 shall b

18、e the average of the two specimensexpressed as a percentage. The compression set of the samplein Option 2 shall be the median (middle most value) of thethree specimens expressed as a percentage.5.2 The standard test specimen shall be a cylindrical diskcut from a laboratory prepared slab.5.2.1 The di

19、mensions of the standard specimens shall be:Type 1A2BThickness, mm (in.) 12.5 0.5(0.49 0.02)6.00.2(0.24 0.01)Diameter, mm (in.) 29.0 0.5(1.14 0.02)13.0 0.2(0.51 0.01)AType 1 specimen is used in Test Methods A, B, and C.BType 2 specimen is used in Test Method B and C.5.2.2 When cutting the standard s

20、pecimen, the circular diehaving the required inside dimensions specified in 5.2.1 shallbe rotated in a drill press or similar device and lubricated bymeans of a soap solution. A minimum distance of 13 mm (0.51in.) shall be maintained between the cutting edge of the die andthe edge of the slab. The c

21、utting pressure shall be as light aspossible to minimize cupping of the cut edges. The dies shallbe maintained carefully so that the cutting edges are sharp andfree of nicks.5.3 An optional method of preparing the standard specimenmay be the direct molding of a circular disk having thedimensions req

22、uired for the test method used and specified in5.2.1.NOTE 1It should be recognized that an equal time and temperature, ifused for both the slab and molded specimen, will not produce anequivalent state of cure in the two types of specimen. A higher degree ofcure will be obtained in the molded specime

23、n. Adjustments, preferably inthe time of cure, must be taken into consideration if comparisons betweenthe specimens prepared by different methods are to be considered valid.NOTE 2It is suggested, for the purpose of uniformity and closertolerances in the molded specimen, that the dimensions of the mo

24、ld bespecified and shrinkage compensated for therein. A two-plate mold with acavity 13.0 6 0.1 mm (0.510 6 0.004 in.) in thickness and 29.20 6 0.05mm (1.148 6 0.002 in.) in diameter, with overflow grooves, will provideType 1 specimens for Test Method A and Test Method B. A similar moldbut having a c

25、avity of 6.3 6 0.3 mm (0.25 6 0.012 in.) in thickness and13.3 6 0.1 mm (0.52 6 0.004 in.) in diameter will provide Type 2specimens for Test Method B.5.4 When the standard test specimen is to be replaced by aspecimen taken from a vulcanized rubber part of greaterthickness than the one indicated in 5.

26、2.1, the sample thicknessshall be reduced first by cutting transversely with a sharp knifeand then followed by buffing to the required thickness inaccordance with Practice D3183.5.5 An alternative method of preparing specimens is byplying up cylindrical disks cut from a standard sheet preparedin acc

27、ordance with Practice D3182 using the specimen sizesspecified in 5.2.1 and cutting as described in 5.2.2, or where adrill press is not available cutting the specimens with a singlestroke from a cutting die.5.5.1 The disks shall be plied, without cementing, to thethickness required. Such plies shall

28、be smooth, flat, of uniformthickness, and shall not exceed seven in number for Type 1specimens and four in number for Type 2 specimens.5.5.2 Care shall be taken during handling and placing of theplied test specimen in the test fixture by keeping the circularfaces parallel and at right angles to the

29、axis of the cylinder.5.5.3 The results obtained on plied specimens may bedifferent from those obtained using solid specimens and theresults may be variable, particularly if air is trapped betweendisks.5.5.4 The results obtained on the specimens prepared by oneof the methods may be compared only to t

30、hose prepared by thesame method.5.6 For routine or product specification testing, it is some-times more convenient to prepare specimens of a different sizeor shape, or both. When such specimens are used, the resultsshould be compared only with those obtained from specimensof similar size and shape a

31、nd not with those obtained withstandard specimen. For such cases, the product specificationshould define the specimen as to the size and shape. If suitablespecimens cannot be prepared from the product, the testmethod and allowable limits must be agreed upon between theproducer and the purchaser.6. C

32、onditioning6.1 Store all vulcanized test specimens or product samplesto be tested at least 24 h but not more than 60 days. When thedate of vulcanization is not known, make tests within 60 daysafter delivery by the producer of the article represented by thespecimen.6.2 Allow buffed specimens to rest

33、at least 30 min beforespecimens are cut for testing.6.3 Condition all specimens before testing for a minimum of3hat236 2C (73.4 6 3.6F). Specimens whose compressionset properties are affected by atmospheric moisture shall beconditioned for a minimum of 24 h in an atmosphere controlledto a relative h

34、umidity of 50 6 10 %RH (40 to 60 %RH).7. Precision and Bias37.1 These precision statements have been prepared in ac-cordance with Practice D4483. Please refer to Practice D4483for terminology and other testing and statistical concepts.7.2 Prepared test specimens of two rubbers for Test MethodsA and

35、B were supplied to five laboratories. These were tested3Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D11-1138.D395 182in duplicate each day on two separate testing days.Atest result,therefore, is the average of two test specim

36、ens, for both TestMethods A and B.7.3 One laboratory did not run the Test Method A testing;therefore, the precision for Test Method A is derived from fourlaboratories.7.4 The Type 1 precision results are given in Table 1 andTable 2.7.5 BiasIn test method statistical terminology, bias is thedifferenc

37、e between an average test value and the reference ortrue test property value. Reference values do not exist for thesetest methods since the value or level of the test property isexclusively defined by the test method. Bias, therefore, cannotbe determined.TEST METHOD ACOMPRESSION SET UNDERCONSTANT FO

38、RCE IN AIR8. Apparatus8.1 MicrometerA micrometer, analog or digital, for mea-suring specimen thickness, in accordance with Practice D3767,Method A1.8.2 Compression Device, consisting of a force applicationspring and two parallel compression plates assembled bymeans of a frame or threaded bolt in suc

39、h a manner that thedevice shall be portable and self-contained after the force hasbeen applied and that the parallelism of the plates shall bemaintained. The force may be applied in accordance with either8.2.1 or 8.2.2.8.2.1 Calibrated Spring Force ApplicationThe requiredforce shall be applied by a

40、screw mechanism for compressinga calibrated spring the proper amount. The spring shall be ofproperly heat-treated spring steel with ends ground and per-pendicular to the longitudinal axis of the spring. A suitablecompression device is shown in Fig. 1. The spring shallconform to the following require

41、ments:8.2.1.1 The spring shall be calibrated at room temperature23 6 5C (73.4 6 9F) by applying successive increments offorce not exceeding 250 N (50 lbf) and measuring thecorresponding deflection to the nearest 0.2 mm (0.01 in.). Thecurve obtained by plotting the forces against the correspondingdef

42、lections shall have a slope of 70 6 3.5 kN/m (400 6 20lbf/in.) at 1.8 kN (400 lbf). The slope is obtained by dividingthe two forces above and below 1.8 kN by the differencebetween the corresponding deflections.8.2.1.2 The original dimensions of the spring shall notchange due to fatigue by more than

43、0.3 mm (0.01 in.) after ithas been mounted in the compression device, compressedunder a force of 1.8 kN (400 lbf), and heated in the oven forone week at 70 6 2C (158 6 3.6F). In ordinary use, a weeklycheck of the dimensions shall show no greater change than thisover a period of 1 year.8.2.1.3 The mi

44、nimum force required to close the spring(solid) shall be 2.4 kN (530 lbf).8.2.2 External Force ApplicationThe required force shallbe applied to the compression plates and spring by externalmeans after the test specimen is mounted in the apparatus.Either a calibrated compression machine or known mass

45、es maybe used for force application. Provision shall be made by theuse of bolts and nuts or other devices to prevent the specimenand spring from losing their initial deflections when theTABLE 1 Type 1 Precision Results, % Compression SetTestMethod AMaterialMeanLevelWithin LaboratoryABetween Laborato

46、ryASrr (r) SRR (R)1 1.73 (%) 0.050 0.142 8.2 0.190 0.54 31.12 26.1 0.898 2.54 9.7 2.37 6.71 25.7ASr= within laboratory standard deviation.r = repeatability (in measurement units).(r) = repeatability (in percent).SR= between laboratory standard deviation.R = reproducibility (in measurement units).(R)

47、 = reproducibility (in percent).TABLE 2 Type 1 Precision Results, % Compression SetTestMethod BMaterialMeanLevelWithin LaboratoryABetween LaboratoryASrr (r) SRR (R)1 13.7 (%) 0.591 1.67 12.2 1.54 4.36 31.82 52.8 0.567 1.60 3.0 5.92 16.8 31.7ASr= within laboratory standard deviation.r = repeatability

48、 (in measurement units).(r) = repeatability (in percent).SR= between laboratory standard deviation.R = reproducibility (in measurement units).(R) = reproducibility (in percent).FIG. 1 Device for Compression Set Test, Using Calibrated SpringLoading, Test Method AD395 183external force is removed. The

49、 spring shall have essentially thesame characteristics as described in 8.2.1, but calibration is notrequired. A suitable compression device is shown in Fig. 2.8.3 PlatesThe plates between which the test specimen iscompressed shall be made of steel of sufficient thickness towithstand the compressive stresses without bending.8.3.1 The surfaces against which the specimen is held shallhave an industrial chrome (hard chrome) plated finish and shallbe cleaned thoroughly and wiped dry before each test.8.3.2 The steel surfaces contacting the rubb