1、Designation: D1076 10Standard Specification forRubberConcentrated, Ammonia Preserved, Creamed, andCentrifuged Natural Latex1This standard is issued under the fixed designation D1076; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision,
2、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.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 This specification covers
3、 requirements for first gradeconcentrated natural rubber latex (see Table 1) of the followingcategories:Category 1Centrifuged Hevea natural latex preservedwith ammonia only or by formaldehyde followed by ammonia.Category 2Creamed Hevea natural latex preserved withammonia only or by formaldehyde foll
4、owed by ammonia.Category 3Centrifuged Hevea natural latex preservedwith low ammonia with other necessary preservatives.Category 4Centrifuged, or centrifuged and creamed, gu-ayule latex, or other natural rubber latex, containing less than200 g total protein per gram dry weight of latex, withammonia o
5、r other hydroxide, with other necessary preserva-tives and stabilizers.Category 5Centrifuged Hevea natural latex treated withaluminum hydroxide or by other means, preserved with am-monia only or by formaldehyde followed by ammonia contain-ing less than 0.5 % non-rubber content.1.2 This specification
6、 is not necessarily applicable to laticesprepared or preserved by other methods, and shall not beconstrued as limiting the desirability or usefulness of othercategories of latices. It does apply to natural latex sources otherthan Hevea brasiliensis but does not apply to compoundedlatex concentrates.
7、1.3 The analytical procedures applicable to the specifica-tions are included and appear in the following order:SectionSampling 6 and 7Total Solids 8Dry Rubber Content 9Protein Content 10Total Alkalinity 11Viscosity 12Sludge Content 13Coagulum Content 14KOH Number 15pH 16Mechanical Stability 17Copper
8、 and Manganese 18Density 19-31Volatile Fatty Acids 32-36Boric Acid 37Dry Films 38Precision for All Test Methods 391.4 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.2. Referenced Documents2.1 ASTM Standards:2D1278 Test Methods
9、 for Rubber from Natural SourcesChemical AnalysisD4483 Practice for Evaluating Precision for Test MethodStandards in the Rubber and Carbon Black ManufacturingIndustriesD5712 Test Method for Analysis of Aqueous ExtractableProtein in Natural Rubber and Its Products Using theModified Lowry Method1This
10、specification is under the jurisdiction ofASTM Committee D11 on Rubberand is the direct responsibility of Subcommittee D11.22 on Natural Rubber.Current edition approved Oct. 1, 2010. Published November 2010. Originallyapproved in 1949. Last previous edition approved in 2006 as D1076 06. DOI:10.1520/
11、D1076-10.2For 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.1Copyright ASTM International, 100 Barr Harbor Drive
12、, PO Box C700, West Conshohocken, PA 19428-2959, United States.D6499 Test Method for The Immunological Measurementof Antigenic Protein in Natural Rubber and its ProductsE70 Test Method for pH of Aqueous Solutions With theGlass Electrode3. General Specification Requirements3.1 In manufacturing, the m
13、aterial shall be processed inaccordance with the best commercial practice and shall be ofuniform composition.3.2 The material shall conform to the chemical and physicalrequirements prescribed in Table 1.4. Significance and Use4.1 This specification denotes limits on the 4 categories oflatex as defin
14、ed in the scope and defines the test methods to usefor the specified properties.These test methods may be used forproduction control or for referee purposes.5. Inspection5.1 Inspection of the material shall be made as agreed uponbetween the purchaser and the seller as part of the purchasecontract.SA
15、MPLING AND METHODS OF TESTING6. Preparations for Sampling6.1 Drums:6.1.1 Open-Head DrumsThe top shall be removed andthe contents stirred with a high-speed stirrer for 10 min.6.1.2 Closed-Head DrumsIf the drum has at least 2 % airspace, which is 20 mm (0.75 in.) on a standard drum, lay it onits side
16、and roll for not less than 10 min. Up end the drum toits original position and allow to stand for 15 min and thenrepeat the rolling operation for at least a further 10 min. In thecase of drums with less than 2 % air space, all of the latex inthe closed-head drum shall be transferred to a larger vess
17、el andmixed with a high-speed stirrer for 10 min.6.2 Tank CarsSamples shall be taken from the top andbottom of the car. If the total solids in the top and bottomsamples agree within 0.5 %, the car shall be considereduniform enough for sampling. If top and bottom samples do notagree within 0.5 %, the
18、 contents of the car shall be agitateduntil samples taken from the top and bottom do agree on totalsolids within 0.5 %.7. Sampling7.1 DrumsAfter preparations for sampling, sample with-out delay. A suitable method is by slowly inserting a clean, dryglass tube of 10 to 15 mm internal diameter and open
19、 at bothends, until it reaches the bottom of the container. Then closethe upper end of the tube and transfer the contents to a clean,dry sample bottle. Repeat the operation until sufficient latexhas been obtained. Alternatively, a specially constructed metalsampling tube may be used, the bottom of w
20、hich can be closedby remote control. No copper or brass shall be used in any partof its construction. At least 10 % of the drums in a shipmentshall be sampled.7.2 Tank CarsSeparate samples of at least 475 cm3eachshall be taken from the top, center, and bottom of the tank car.Take the top sample firs
21、t, then the center sample, and thebottom sample last. Use a weighted sampler with a remotelyoperated removable top, or other suitable sampling device thatwill accomplish the same results. Blend the three samplesthoroughly. Each sample shall be poured immediately into atightly stoppered container. Th
22、e three samples shall be com-bined and thoroughly blended into a composite sample.At least950 cm3of this composite sample shall be used for test. Onecomposite sample only is required from each tank car.8. Total Solids8.1 ApparatusTared, covered, flat-bottom weighing dishapproximately 60 mm (2.5 in.)
23、 in diameter, which may bemade of glass, tinned metal, or aluminum.8.2 ReagentDistilled water.TABLE 1 Requirements for Specified Latex CategoriesCategory 1 Category 2 Category 3 Category 4 Category 5Total solids, min,% 61.3 66.0 61.3 44.0 61.3Dry rubber content (DRC),Amin, % 59.8 64.0 59.8 42.0 60.8
24、Total solids content minus dry rubbercontent, max,%2.0 2.0 2.0 2.0 0.5Protein content (g/g dw latex)Total protein by D5712 200 maxHevea antigenic protein by D6499 None detectableTotal alkalinity calculated as ammonia,as % latex0.60 min 0.55 min 0.29 max 0.60 min 0.60 minOr: total alkalinity calculat
25、ed as KOH,as % latex0.10 minSludge content, max, % 0.10 0.10 0.10 0.10 0.1Coagulum content, max, % 0.050 0.050 0.050 0.050 0.05KOH number, maxB0.80 0.80 0.80 0.80 0.8Mechanical stability, s, min 650 650 650 90 650Copper content, max, % of total solids 0.0008 0.0008 0.0008 0.0008 0.0008Manganese cont
26、ent, max, % of totalsolids0.0008 0.0008 0.0008 0.0008 0.0008Color on visual inspection no pronounced blue or grayCOdor after neutralization with boric acid no putrefactive odorADry rubber content by definition and use is the acid coagulable portion of latex after washing and drying.BIt is accepted t
27、hat KOH numbers for boric acid preserved latices will be higher than normal, equivalent to the amount of boric acid in the latex.CBlue or gray color usually denotes iron contamination caused by improper storage in containers.D1076 1028.3 ProcedureWeigh 2.5 6 0.5 g of the latex to thenearest 1 mg in
28、the tared, covered weighing dish. Remove thecover and distribute the latex over the bottom of the dish overan area of approximately 32 cm2(5 in.2). This may befacilitated by carefully adding approximately 1 cm3of distilledwater to the latex and gently swirling the dish. With the dishuncovered, dry t
29、he specimen in a vented air oven for 16 h at 706 2Cor2hat1006 2C. Replace the cover, cool in adesiccator to room temperature, and weigh. Repeat drying andweighing until the mass is constant to 1 mg or less. Tests shallbe run in duplicate and shall check within 0.15 %. The averageof the two determina
30、tions shall be taken as the result.8.4 CalculationsCalculate the percentage of total solidsas follows:Total solids, % 5 C 2 A!/B 2 A!# 3 100 (1)where:A = mass of the weighing dish, g,B = mass of the dish plus the original sample, g, andC = mass of the dish plus the dried sample, g.9. Dry Rubber Cont
31、ent9.1 ApparatusPorcelain evaporating dish approximately100 mm in diameter and 50 mm deep.9.2 ReagentAcetic acid aqueous solution (20 Mg/m3).9.3 Weigh approximately 10 g of the latex to the nearest 1mg into a porcelain evaporating dish, and add distilled wateruntil the total solids content is approx
32、imately 25 %. Addsufficient acetic acid (2 %), while stirring constantly over a5-min period, to coagulate completely the latex (80 cm3shouldbe sufficient). Category 4 guayule latex may also require theaddition of up to 20 mLhydrochloric acid (2 %) to complete itscoagulation.9.3.1 Place the dish on a
33、 steam bath and leave undisturbedfor 15 to 30 min.Aclear serum should result, and 30 min is themaximum time allowed. If the serum is milky, the acid waseither added too fast or in insufficient amount and the proce-dure should be repeated until a clear serum results. Pick upcoagulated latex particles
34、 with the main body of the coagulum.Wash coagulum in running water and pass between rolls.Repeat this process 5 times and reduce the sheet of coagulatedrubber to a maximum thickness of 2 mm and dry at 70 6 2Cin a vented air oven atmosphere. If oxidation occurs, the testmay be run with the option of
35、using a drying temperature of 556 2C, or an antioxidant may be added to the latex beforecoagulation. If polymer oxidation occurs, the test may be rerunwith the option of using a drying temperature of 55 6 2C.Cool in a desiccator to room temperature and weigh. Repeatdrying and weighing until the mass
36、 is constant to 1 mg or less.9.4 Duplicate samples shall be run and shall check within0.2 %. The average of the two determinations shall be taken asthe result.9.5 CalculationCalculate the dry rubber content as fol-lows:Dry rubber content, % 5 mass of dry coagulum/mass of sample 3 100(2)10. Protein C
37、ontent10.1 Total ProteinSolubilize latex proteins in1%SDSand 50 mM sodium phosphate buffer (final concentration) andthen quantify using the modified Lowry test according to TestMethod D5712.10.1.1 Solubilization MethodMix latex sample (500 l)with 450 l 100 mM sodium phosphate buffer (1:1) into three
38、microfuge tubes for each sample; add 50 l 20 % SDS intoeach tube, mix; incubate at 25C for 2 h with shaking at200 rpm; spin for 5 min, remove rubber pad; transfer aqueousphase into new tubes and spin again to clarify; divide eachsample into 3 3 0.6 mL tubes for each sample (these can bestored at 4C
39、overnight); prepare bovine serum albuminstandards in extraction buffer at 0, 5, 10, 15, 25, 50, 100, 200,300, and 400 g/mL; add 60 l 1.5 mg/mL sodium deoxycho-late to samples and standards, mix, stand for 10 min; add 120l of 72 % freshly mixed trichloroacetic acid and phospho-tungstic acid (1:1) int
40、o each sample, mix, incubate for 30 minat RT; spin 15 min at 6000 xg, remove supernatant, air drypellet; suspend each pellet in 250 l 0.2 M sodium hydroxideand store at 4C until assayed; assay within 24 h using themodified Lowry test according to Test Method D5712.10.2 Hevea Antigenic ProteinSolubil
41、ize latex proteinswith 1 % SDS and 50 mM sodium phosphate buffer (finalconcentration) then quantify using the antigenic protein assayaccording to Test Method D6499.11. Total Alkalinity11.1 ApparatusGlass electrode pH meter.11.2 Reagent0.1 mol standard HCl.11.3 Preparation of SpecimenPlace approximat
42、ely5goflatex into a glass weighing bottle of approximately 10-cm3capacity, having a ground glass cap, and weigh to the nearest1 mg. Pour the specimen into a beaker containing approxi-mately 300 cm3of distilled water, restopper quickly to preventloss of ammonia, and set aside for reweighing. The spec
43、imenmass is equal to the difference between the two weighings. Thetransfer of the sample to the beaker shall be done in such a waythat no latex runs down the outside of the weighing bottle.11.4 Recommended ProcedureInsert the electrodes of acalibrated glass electrode pH meter into the liquid and not
44、e thepH. The meter should be calibrated and the pH measurementsmade in accordance with Test Method E70, and the directionsgiven by the manufacturer of the meter. Slowly, and whilestirring constantly, add 0.1 mol HCl until a pH of 6.0 isreached. Too rapid addition or inadequate stirring of the sample
45、while the acid is being added may cause local coagulation ofthe rubber. With samples of unknown alkalinity, it is recom-mended that the acid be added in 1-cm3increments, and a pHreading taken 10 s after each addition. As the pH of 6.0 isapproached, smaller increments should be added.11.5 Alternative
46、 ProcedurePrepare the sample as de-scribed in 11.3. Add 6 drops of a 0.10 % alcoholic solution ofmethyl red and titrate with approximately 0.1 mol HCl until theindicator turns pink. The end point occurs before completecoagulation takes place and the color change of the indicatorcan be detected again
47、st the white background of the slightlycoagulated latex.D1076 10311.6 CalculationCalculate the total alkalinity, reported asNH3based on grams of NH3per 100 g of latex as follows:Total alkalinity, as NH3! % 5 1.7 3 M 3 n!/W (3)where:M = mole of the standard HCl,n = volume of standard HCl required, cm
48、3, andW = original mass of the latex, g.11.6.1 If total alkalinity is wanted as KOH, the followingcalculation applies to both procedures:Total alkalinity, as KOH! % 5 5.61 3 M 3 n!/W (4)where:M = mole of the standard HCl,n = volume of standard HCl required, cm3, andW = original mass of the latex, g.
49、11.6.2 If total alkalinity is wanted based on the water phaseof the latex, calculate as follows:Total alkalinity, as % of water 5 1.7 3 M 3 n!/W1 2 TS/100!(5)where:TS = percent total solids,M = mole of the standard HCl,n = volume of standard HCl required, cm3, andW = original mass of the latex, g.11.6.3 If total alkalinity is wanted as KOH based on thewater phase of the latex, calculate as follows:Total alkalinity, as KOH! as % of water 5 5.61 3 M 3 n!/W12 TS/100! (6)where:TS = percent total solids,M = mole of the standard H
