1、Designation: D 3194 04Standard Test Method forRubber From Natural SourcesPlasticity Retention Index(PRI)1This standard is issued under the fixed designation D 3194; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last r
2、evision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method gives an indication of the oxidationresistance of raw natural rubber at a specified temperature. Thisresis
3、tance is indicated by the Plasticity Retention Index (PRI),a ratio expressed as a percentage of the aged plasticity to theoriginal plasticity determined by means of a parallel plateplastometer. A low PRI value indicates a poor resistance tooxidation.1.2 The values stated in SI units are to be regard
4、ed as thestandard.1.3 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-bility of regulatory limitations prior to u
5、se.2. Referenced Documents22.1 ASTM Standards:D 1485 Test Methods for Rubber from Natural SourcesSampling and Sample PreparationD 3040 Practice for Preparing Precision Statements forStandards Related to Rubber and Rubber Testing3D 3182 Practice for RubberMaterials, Equipment, andProcedures for Mixin
6、g Standard Compounds and Prepar-ing Standard Vulcanized SheetsE 145 Specification for Gravity-Convection and Forced-Ventilation Ovens3. Summary of Test Method3.1 A homogenized sample of raw rubber is prepared by aspecified procedure to create a sheet from which six cylindricalpellets of specified di
7、mensions are cut, three to be tested inoriginal condition and three to be aged under specified condi-tions.3.2 Plasticity on both the original and aged samples ismeasured as the median final thickness of each set of samplesafter a compressive force of 100 N 6 1 N is applied for aspecified time. The
8、PRI is the ratio expressed as a percentageof the aged to the original plasticity.4. Significance and Use4.1 This test method may be used to evaluate the heat and/oroxidation stability (aging) of raw rubber under controlledconditions. High original and aged plasticity values usuallycorrespond to good
9、 aging properties. The ratio of the aged tooriginal plasticity values expressed as a percentage, the PRI, isused as an indication of aging.5. Apparatus5.1 Parallel Plate Plastometer4, with a 10 mm diameterplaten. The platen temperature shall be 100 6 1C and theplastometer shall have a timer unit cap
10、able of giving a 15 6 1s initial conditioning period during which the sample shall becompressed to 1 6 0.01 mm and a test period of 15 6 1 s undera compression force of 100 N 61 N. The plastometer shall alsohave a measuring device gauge reading to 0.01 mm. Calibra-tion procedures recommended by the
11、manufacturer of theplastometer should be followed.5.2 Punch, that will die out cylindrical specimens approxi-mately 13 mm in diameter from a prepared sheet of rubber.1This method is under the jurisdiction of ASTM Committee D11 on Rubber andis the direct responsibility of Subcommittee D11.22 on Natur
12、al Rubber.Current edition approved Feb. 1, 2004. Published February 2004. Originallyapproved in 1973. Last previous edition approved in 1999 as D 3194 99.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMS
13、tandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn.4The sole source of supply of the Wallace Rapid Plastimeter known to thecommittee at this time is Leverett A. Anderson Co., P.O. Box 5400, Akron, OH44313. If you are aware of alternative suppliers
14、, please provide this information toASTM International Headquarters. Your comments will receive careful consider-ation at a meeting of the responsible technical committee1, which you may attend.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, Unite
15、d States.5.3 Circulating Air Oven, specified in Specification E 145,Type IIA. The oven must be capable of maintaining 140 60.5C.5.4 Dishes or Tray, aluminum, for test specimens, light-weight aluminum dishes approximately 38 mm (1.5 in.) indiameter or an aluminum tray approximately 150 by 150 mm(7 by
16、 7 in.) for aging specimens in the oven.5.5 Tissue paper or cigarette paper, approximately 40 by 40mm (1.5 by 1.5 in.). This paper shall be bleached, unglazedacid-free tissue paper, of approximately 1.7 g/m2.6. Precautions6.1 The initial thickness of the prepared sheet can affect thefinal thickness
17、after testing. Ascertain the required mill openingby preliminary trial; it will vary with the rubber and the mill.6.2 The temperature and speed of the testing operations canaffect the results. An increase in temperature or the time topreheat or time to read the dial micrometer can result in low,fina
18、l plasticity readings.7. Sampling7.1 The natural rubber sample shall be obtained in accor-dance with Method D 1485.8. Test Specimen Preparation8.1 Homogenize the piece to be tested (mass approximately360 g) 10 times through a mill as described in Practice D 3182.The mill rolls should be at 70 6 5C w
19、ith an opening ofapproximately 1.65 mm (0.065 in.). After each of the first sixpasses, roll the rubber into a cylinder and pass endwise throughthe mill rolls. After the sixth pass, the sample shall not berolled, but is folded.8.2 Take a test portion of about 30 g from the homogenizedsample and pass
20、it three times (doubling the sheet betweenpasses) between mill rolls at room temperature with theopening adjusted so that the final sheet thickness is approxi-mately 1.7 mm (0.07 in.). After the third pass, double the sheet,which should be uniform in texture and free of holes, and pressthe two halve
21、s lightly together.8.3 Die out six or more test specimens from the doubledsheet with the punch and measure their thickness until six testpellets are obtained with a thickness of 3.4 6 0.2 mm (0.134 60.008 in.) having a volume of 0.40 6 0.04 cm3. Randomlydivide these into two sets of three, one for t
22、est before aging andthe other for test after aging.9. Procedure9.1 Aging:9.1.1 Before aging is started, the oven must be stabilized at140 6 0.5C for at least12 h.9.1.2 The dishes or tray containing the three pellets (8.3) tobe aged must be arranged within the calibrated region of theoven. Insert the
23、 tray and close the oven door quickly to preventexcessive oven heat loss. Start timing as soon as the oven dooris closed.9.1.3 After 30 6 0.25 min remove the tray from the ovenand remove the dishes from the tray. Allow them to cool toroom temperature for a minimum of 30 min and a maximum of2 h befor
24、e testing.9.2 Measurement of Plasticity:9.2.1 The platen of the plastometer shall have come toequilibrium at 100 6 1C for 15 min before making measure-ments.9.2.2 Place two pieces of tissue paper (5.5) between theheated platens and set the thickness measuring device to zerowhen the platens are close
25、d.9.2.3 Insert a pellet at room temperature between two piecesof tissue paper and place the whole assembly centrally betweenthe heated platens. Put the machine lever into operation. Aftera 15-s conditioning period, the timing device automaticallyreleases the force of 100 N 61 N to compress the speci
26、men.This load period is automatically adjusted, exactly 15-s dura-tion. The final thickness expressed in units equivalent to 0.01mm remains locked after the 15s load period on the dialmicrometer until the operating handle is moved to open theinstrument. Record the measured thickness from the dialmic
27、rometer. Repeat the above for each of the pellets, both agedand in original condition.9.2.4 The measured thickness for each pellet within either ofthe groups should not vary by more than 6 0.01 mm from themedian value of that group. Run additional pellets, if needed,to get three of each group within
28、 this tolerance.10. Calculation10.1 The plasticity is 100 times the final thickness asexpressed in units equivalent to 0.01 mm.10.2 Using the median values of these plasticity results ofboth original (Po) and aged test specimens, calculate the PRI asfollows:PRI 5plasticity aged/plasticity original!3
29、100 (1)11. Report11.1 The report shall include the following:11.1.1 Three values of the plasticity for the original and theaged test pieces,11.1.2 Type of oven used, and11.1.3 Plasticity Retention Index (PRI).12. Precision and Bias512.1 This precision and bias section has been prepared inaccordance
30、with Practice D 4483. Refer to this practice forterminology and other statistical details.12.2 The precision results in this precision and bias sectiongive an estimate of the precision of the test method with thematerials used in the particular interlaboratory program asdescribed below. The precisio
31、n parameters should not be usedfor acceptance/rejection testing of any group of materialswithout documentation that they are applicable to those par-ticular materials and the specific testing protocols that includethis test method.12.3 A Type 1, Class II interlaboratory precision programwas conducte
32、d (except for sample No. 6, which was Type 1,Class I). Both repeatability and reproducibility are short term.A period of a few days separate test results, which were5Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR: D111066.D31940
33、42repeated on three separate days. Participation included 13laboratories, and six materials were used. Therefore, p = 13, q= 6, and n = 3. A test result is the median value obtained fromthree determinations as specified in Section 10.12.4 Other than sample No. 1, which was IIR, the materialsused wer
34、e natural rubber. They were prepared through step 8.2of this test method. Participants were required to die out andtest the cut pellets. Sample identification: No. 1 = Butyl rubber,No. 2 = PA80 coagulated latex, No. 3 = SIR20, No. 4 = No.1RSS, No. 5 = CV50, and No. 6 = SIR20 cut pellets.12.5 The res
35、ults of the precision calculations are given inTable 1, with the materials arranged in increasing mean PRIvalue.12.6 The precision for these tests on a relative basis may beexpressed as follows (sample No. 1 IIR excluded):12.6.1 Repeatability The repeatability (r) of this test hasbeen established as
36、 9.8 %. Two single measurements (determi-nations) that differ by more than the tabulated (r) (expressed aspercentage of their mean value) must be considered suspect,that is, having arisen from different sample populations. Sucha decision dictates that appropriate action be taken.12.6.2 Reproducibili
37、ty The reproducibility (R) of this testhas been established as 34.5 %. Two single measurements(determinations) that differ by more than the tabulated (R)(expressed as percentage of their mean value) must be consid-ered suspect, that is, having arisen from different samplepopulations. Such a decision
38、 dictates that appropriate action betaken.12.7 BiasIn test method terminology, bias is the differ-ence between an average test value and the reference (true) testproperty value. Reference values do not exist for this testmethod since the value or level of the test property isexclusively defined by t
39、he test method. Bias, therefore, cannotbe determined.13. Keywords13.1 natural rubber; plasticity; P.R.I.; retention indexASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expres
40、sly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised,
41、 either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may at
42、tend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States.
43、 Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).TABLE 1 ASTM Test Method D 3194 Type 1 PrecisionWallacePlast
44、icity (PRI)ABSampleMeanValueWithin Laboratories Between Laboratoriessrr (r) SRR (R)6 58.95 2.58 7.30 12.4 9.33 26.41 44.84 63.22 1.70 4.82 7.6 4.91 13.88 22.03 63.44 2.22 6.28 9.9 9.40 26.57 41.95 79.56 2.10 5.94 7.5 7.31 20.68 26.02 87.23 3.34 9.45 10.8 10.79 30.55 35.01C95.15 1.95 5.52 5.8 2.52 7.
45、13 7.5Mean 70.48Pooled 2.45 6.94 9.8 8.6 24.32 34.5AThis is short-term precision with p = 13, q = 6, and n =3.sr= Within laboratory standard deviation,r = Repeatability in measured units (srx 2.83),(r) = Repeatability in percent (r/mean) x 100),SR= Between laboratory standard deviation,R = Reproduci
46、bility in measured units (SRx 2.83), and(R) = Reproducibility in percent (R/mean) x 100).Outliers have been rejected from the tabled data.BUnits: PRI is the ratio expressed as a percentage of the aged to the originalplasticity. The basic plasticity units represent the thickness of the samples in 0.01mm times 100.CSample No. 1 excluded from mean and pooled values.D3194043
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