1、Designation: D1485 07 (Reapproved 2015)Standard Practice forRubber from Natural SourcesSampling and SamplePreparation1This standard is issued under the fixed designation D1485; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the ye
2、ar 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. Scope1.1 This practice, intended for referee purposes, covers auniform procedure for sampling lots of solid natural rubbe
3、r.Natural rubber 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 obv
4、ious heterogeneity 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
5、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 use.2. Referenced Documents2.1 ASTM Standards:2D1278 Test Methods for Rubber from Natural SourcesChemical AnalysisD3182 Practice
6、 for RubberMaterials, Equipment, and Pro-cedures for Mixing Standard Compounds and PreparingStandard Vulcanized SheetsD3184 Practice for RubberEvaluation of NR (NaturalRubber)2.2 ANSI Standard:Z1.9 Sampling Procedures and Tables for Inspection byVariables for Percent Defective33. Significance and Us
7、e3.1 This 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. Samplin
8、g4.1 Sample 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 c
9、onsumer 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 surf
10、aces of 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 th
11、e test portion, or wrap it tightly intwo layers of aluminum foil until tested.NOTE 2In testing for volatile matter only, a sample weighingapproximately 150 g may be taken as a continuous piece from any part ofthe bale.5. Lot Acceptability5.1 Each property of the lot is evaluated separately. Therequi
12、rements 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 from1This practice is under the jurisdiction of ASTM Committee D11 on R
13、ubber andis the direct responsibility of Subcommittee D11.22 on Natural Rubber.Current edition approved Aug. 1, 2015. Published October 2015. Originallyapproved in 1957. Last previous edition approved in 2011 as D1485 07 (2011).DOI: 10.1520/D1485-07R15.2For referenced ASTM standards, visit the ASTM
14、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.3Available from American National Standards Institute, 25 W. 43rd St., 4thFloor, New York, NY 10036.Copyrigh
15、t ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1this index, an estimate is made of the percent of the lot that isdefective. If this percentage does not exceed the allowablevalues shown in Table 1, the lot is considered acceptable.5.2 Quality
16、Index Calculations:5.2.1 For a requirement having a maximum limit, calculatethe quality index as follows: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 requirem
17、ent having a minimum limit, calculatethe 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 thespecification.5.3 Acceptability:5.3.1 For a quality characteristic having a single specifica-tion limit, a lot is acceptable if th
18、e quality index equals orexceeds 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
19、 the appropriate sample size 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 port
20、ion to the nearest0.1 g and then homogenize by passing it ten times between therolls of a standard laboratory mill which is in accordance withPractice D3182. 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 p
21、ass and insert the rollendwise 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 D1278. Place
22、 the homogenized rubber in anairtight 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 accor
23、dance with Test Methods D1278.6.3 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 MethodsD3184.7. Precision and Bias7.1 Precision and bias statements are not directly applicableto these sampling
24、 methods, but they are pertinent to individualtest methods that will use these sampling methods.8. Keywords8.1 natural rubber; sample preperation; samplingTABLE 1 Sampling PlanNOTE 1The sampling plan is based on Inspection Level III, ANSIZ1.9, and an Acceptable Quality Level of 2.5 %.Lot Size, kg (l
25、b)SampleSizeQ Value,minAAllow-ablePercentDefective,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
26、to 110 200) 15 1.47 6.650 001 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 De
27、fectiveSampleSize3 4 5 7 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 1
28、1.2 11.3 11.41.25 . 8.7 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
29、3.8 4.01.75 . . 0.2 2.1 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 . . . . .
30、0.1 0.22.70 . . . . . 0.1 0.12.80 . . . . . . 0.12.90 . . . . . . .D1485 07 (2015)2ASTM 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
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