1、Designation: D 1485 07Standard Practice forRubber from Natural SourcesSampling and SamplePreparation1This standard is issued under the fixed designation D 1485; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revis
2、ion. 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 practice, intended for referee purposes, covers auniform procedure for sampling lots of solid natural rubber.Natural rubbe
3、r generally is marketed in bales or packages ofvarious sizes.1.2 A procedure for determining the acceptability of lots ofnatural rubber is given. This procedure is based on a variablesampling plan.1.3 The sample size is based on the assumption of a visuallyhomogeneous material. If obvious heterogene
4、ity exists, thenumber of samples shall be increased.1.4 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsib
5、ility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 1278 Test Methods for Rubber from Natural SourcesChemical AnalysisD 3182 Practice for RubberMa
6、terials, Equipment, andProcedures for Mixing Standard Compounds and Prepar-ing Standard Vulcanized SheetsD 3184 Test Methods for RubberEvaluation of NR(Natural Rubber)2.2 ANSI Standard:Z1.9 Sampling Procedures and Tables for Inspection byVariables for Percent Defective33. Significance and Use3.1 Thi
7、s practice outlines a procedure for sampling andsample preparation of natural rubber. A statistical method fordetermining a quality index and lot acceptability is given. Thesampling plan is optional for quality control or production, butmay be used when needed for referee purposes.4. Sampling4.1 Sam
8、ple SizeThe number of samples to be selected torepresent the lot shall be determined by the size of the lot asindicated in Table 1. A sample bale is selected randomly fromthe lot for each sample required.NOTE 1The sampling plan is more efficient for large lots. The risk forthe producer and consumer
9、decreases as the sample size increases.4.2 Removal of Test Portion:4.2.1 From each sample bale selected, cut one 600 to 1500-gtest portion of rubber, depending on the tests to be made. Eachtest portion is tested separately. Cut the test portion through theentire bale, normal to the bale surfaces of
10、the largest area,without the use of lubricant. Remove outer wrapping sheets,polyethylene film, bale coating, or other extraneous surfacematerial from the test portion. Unless the test portion is to betested immediately, place it in an airtight container of not morethan twice the volume of the test p
11、ortion, or wrap it tightly intwo layers of aluminum foil until tested.NOTE 2In testing for volatile matter only, a sample weighing approxi-mately 150 g may be taken as a continuous piece from any part of the bale.5. Lot Acceptability5.1 Each property of the lot is evaluated separately. Therequiremen
12、ts of these tests are of two types: (1) those having asingle limit such as a minimum or maximum and (2) thosehaving double limits, that is, a minimum and a maximum. Aquality index is calculated for each property tested, and fromthis index, an estimate is made of the percent of the lot that isdefecti
13、ve. If this percentage does not exceed the allowablevalues shown in Table 1, the lot is considered acceptable.5.2 Quality Index Calculations:5.2.1 For a requirement having a maximum limit, calculatethe quality index as follows:1This practice is under the jurisdiction of ASTM Committee D11 on Rubber
14、andis the direct responsibility of Subcommittee D11.22 on Natural Rubber.Current edition approved March 1, 2007. Published April 2007. Originallyapproved in 1957. Last previous edition approved in 2002 as D 1485 86 (2002).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontac
15、t ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute, 25 W. 43rd St., 4thFloor, New York, NY 10036.1Copyright ASTM International, 100 Barr
16、 Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.Q 5 U 2 X!/S (1)where:Q = quality index,U = maximum value permitted by the specification,X= mean of all sample values obtained, andS = standard deviation of the sample values.5.2.2 For a requirement having a minimum limit, c
17、alculatethe quality index as follows:Q 5 X2 L!/S (2)where:Q, X, and S = same as those for maximum value andL = minimum value permitted by the specifica-tion.5.3 Acceptability:5.3.1 For a quality characteristic having a single specifica-tion limit, a lot is acceptable if the quality index equals orex
18、ceeds the minimum quality index shown in Table 1 for theapplicable lot and sample size.5.3.2 For a quality characteristic having both an upper andlower specification limit, estimate the percentages of the lotabove the upper limit and below the lower limit from Table 2using the appropriate sample siz
19、e and quality index valuescalculated in 5.2. A lot is acceptable if the sum of the twopercentages does not exceed the maximum allowable percentdefective shown in Table 1 for the lot size being evaluated.6. Preparation of Rubber for Test6.1 HomogenizationWeigh the test portion to the nearest0.1 g and
20、 then homogenize by passing it ten times between therolls of a standard laboratory mill which is in accordance withPractice D 3182. Set the clearance between the rolls at 1.30 60.15 mm and maintain the temperature of the roll surfaces at 706 5C. Roll the rubber after each pass and insert the rollend
21、wise on the next pass. Return any particles separatingduring homogenization to the rubber. On the tenth pass, sheetthe rubber and weigh it to the nearest 0.1 g. Use the initial andfinal masses in the calculation of volatile matter in accordancewith Test Methods D 1278. Place the homogenized rubber i
22、nan airtight container of not more than twice the volume of therubber or wrap tightly in two layers of aluminum foil untilrequired for test.6.2 Chemical TestsCut specimens from the homogenizedrubber in such amounts as are required for the specificchemical tests made in accordance with Test Methods D
23、 1278.6.3 Standard CompoundCut a portion of 400 g from thehomogenized rubber for the preparation of a standard com-pound for physical tests in accordance with Test MethodsD 3184.7. Precision and Bias7.1 Precision and bias statements are not directly applicableto these sampling methods, but they are
24、pertinent to individualtest methods that will use these sampling methods.8. Keywords8.1 natural rubber; sample preperation; samplingTABLE 1 Sampling PlanNOTEThe sampling plan is based on Inspection Level III, ANSI Z1.9,and an Acceptable Quality Level of 2.5 %.Lot Size, kg (lb)SampleSizeQ Value,minAA
25、llow-ablePercentDefec-tive,maxB300 to 4 000 (600 to 8 800) 3 1.12 7.64 001 to 6 500 (8 801 to 14 300) 4 1.17 10.96 501 to 11 000 (14 301 to 24 200) 5 1.24 9.811 001 to 18 000 (24 201 to 39 700) 7 1.33 8.418 001 to 30 000 (39 701 to 66 100) 10 1.41 7.330 001 to 50 000 (66 101 to 110 200) 15 1.47 6.65
26、0 001 to 80 000 (110 201 to 176 400) 20 1.51 6.2AMinimum value of Q for quality characteristics having single specification limit.BMaximum allowable percent defective for quality characteristics having bothupper and lower specification limit.TABLE 2 Estimate of Lot Percent DefectiveSampleSize3 4 5 7
27、 101520Q Value Estimated Percent of Lot Above or Below Limit0.95 19.3 18.3 17.9 17.5 17.3 17.2 17.21.00 16.7 16.7 16.4 16.1 16.0 15.9 15.91.05 13.7 15.0 14.9 14.8 14.7 14.7 14.71.10 9.8 13.3 13.5 13.5 13.5 13.5 13.51.15 0.3 11.7 12.1 12.3 12.3 12.4 12.41.20 . 10.0 10.8 11.1 11.2 11.3 11.41.25 . 8.7
28、9.7 10.2 10.4 10.5 10.61.30 . 6.7 8.2 8.9 9.2 9.4 9.51.35 . 5.0 7.0 7.9 8.3 8.5 8.61.40 . 3.3 5.9 7.0 7.4 7.7 7.81.45 . 1.7 4.8 6.1 6.6 6.9 7.01.50 . . 3.8 5.3 5.9 6.2 6.31.55 . . 2.9 4.5 5.2 5.5 5.71.60 . . 2.0 3.8 4.5 4.9 5.11.65 . . 1.3 3.2 4.0 4.4 4.51.70 . . 0.7 2.6 3.4 3.8 4.01.75 . . 0.2 2.1
29、2.9 3.4 3.61.80 . . . 1.7 2.5 2.9 3.11.85 . . . 1.3 2.1 2.6 2.81.90 . . . 0.9 1.8 2.2 2.41.95 . . . 0.6 1.4 1.9 2.12.00 . . . 0.4 1.2 1.6 1.82.10 . . . 0.1 0.7 1.2 1.32.20 . . . . 0.4 0.8 1.02.30 . . . . 0.2 0.5 0.72.40 . . . . 0.1 0.3 0.52.50 . . . . . 0.2 0.32.60 . . . . . 0.1 0.22.70 . . . . . 0.
30、1 0.12.80 . . . . . . 0.12.90 . . . . . . .D1485072ASTM 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 expressly advised that determination of the validity of any such patent righ
31、ts, 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, either reapproved or withdrawn. Your comments are invited either for
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33、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. 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).D1485073
