1、Designation: D 1076 06Standard Specification forRubberConcentrated, Ammonia Preserved, Creamed, andCentrifuged Natural Latex1This standard is issued under the fixed designation D 1076; 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 (e) 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 cov
3、ers 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 f
4、ollowed 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, withammoni
5、a or other hydroxide, with other necessary preserva-tives and stabilizers.1.2 This specification 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 natura
6、l latex sources otherthan Hevea brasiliensis but does not apply to compoundedlatex concentrates.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 1
7、1Viscosity 12Sludge Content 13Coagulum Content 14KOH Number 15pH 16Mechanical Stability 17Copper 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 p
8、arentheses are for informationonly.2. Referenced Documents2.1 ASTM Standards:2D 1278 Test Methods for Rubber from Natural SourcesChemical Analysis1This specification is under the jurisdiction ofASTM Committee D11 on Rubberand is the direct responsibility of Subcommittee D11.22 on Natural Rubber.Curr
9、ent edition approved June 1, 2006. Published June 2006. Originallyapproved in 1949. Last previous edition approved in 2002 as D 1076 02.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume in
10、formation, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.D 4483 Practice for Evaluating Precision for Test MethodStandards in the Rubber and Carbon Black Manufacturing
11、IndustriesD 5712 Test Method for Analysis of Aqueous ExtractableProtein in Natural Rubber and Its Products Using theModified Lowry MethodD 6499 Test Method for The Immunological Measurementof Antigenic Protein in Natural Rubber and its ProductsE70 Test Method for pH of Aqueous Solutions With theGlas
12、s Electrode3. General Specification Requirements3.1 In manufacturing, the material 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 Us
13、e4.1 This specification denotes limits on the 4 categories oflatex as defined 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
14、uponbetween the purchaser and the seller as part of the purchasecontract.SAMPLING 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 %
15、 airspace, which is 20 mm (0.75 in.) on a standard drum, lay it onits side 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, al
16、l of the latex inthe closed-head drum shall be transferred to a larger vessel 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 e
17、nough for sampling. If top and bottom samples do notagree within 0.5 %, the 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
18、 inserting a clean, dryglass tube of 10 to 15 mm internal diameter and open 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. Alternative
19、ly, a specially constructed metalsampling tube may be used, the bottom of which 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 take
20、n from the top, center, and bottom of the tank car.Take the top sample first, 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. Ea
21、ch sample shall be poured immediately into atightly stoppered container. The 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.TABLE 1 Requirements fo
22、r Specified Latex CategoriesCategory 1 Category 2 Category 3 Category 4Total solids, min,% 61.3 66.0 61.3 44.0Dry rubber content (DRC),Amin, % 59.8 64.0 59.8 42.0Total solids content minus dry rubbercontent, max,%2.0 2.0 2.0 2.0Protein content (g/g dw latex)Total protein by D 5712 200 maxHevea antig
23、enic protein by D 6499 None detectableTotal alkalinity calculated as ammonia,as % latex0.60 min 0.55 min 0.29 max 0.60 minOr: total alkalinity calculated as KOH,as % latex0.10 minSludge content, max, % 0.10 0.10 0.10 0.10Coagulum content, max, % 0.050 0.050 0.050 0.050KOH number, maxB0.80 0.80 0.80
24、0.80Mechanical stability, s, min 650 650 650 90Copper content, max, % of total solids 0.0008 0.0008 0.0008 0.0008Manganese content, max, % of totalsolids0.0008 0.0008 0.0008 0.0008Color on visual inspection no pronounced blue or grayCOdor after neutralization with boric acid no putrefactive odorADry
25、 rubber content by definition and use is the acid coagulable portion of latex after washing and drying.BIt is accepted that 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 contaminat
26、ion caused by improper storage in containers.D10760628. Total Solids8.1 ApparatusTared, covered, flat-bottom weighing dishapproximately 60 mm (2.5 in.) in diameter, which may bemade of glass, tinned metal, or aluminum.8.2 ReagentDistilled water.8.3 ProcedureWeigh 2.5 6 0.5 g of the latex to theneare
27、st 1 mg in 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 dishuncov
28、ered, dry the 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 tw
29、o determinations 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
30、Rubber Content9.1 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 conten
31、t is approximately 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 th
32、e dish on a 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 late
33、x particles 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
34、 option of 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 unt
35、il the mass 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
36、. Protein Content10.1 Total ProteinSolubilize latex proteins in1%SDSand 50 mM sodium phosphate buffer (final concentration) andthen quantify using the modified Lowry test according to TestMethod D 5712.10.1.1 Solubilization MethodMix latex sample (500 l)with 450 l 100 mM sodium phosphate buffer (1:1
37、) into threemicrofuge 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 bes
38、tored at 4C 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 ac
39、id (1:1) into 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 D 5712.10.2 Hevea Antigenic P
40、roteinSolubilize latex proteinswith 1 % SDS and 50 mM sodium phosphate buffer (finalconcentration) then quantify using the antigenic protein assayaccording to Test Method D 6499.11. Total Alkalinity11.1 ApparatusGlass electrode pH meter.11.2 Reagent0.1 mol standard HCl.11.3 Preparation of SpecimenPl
41、ace approximately5goflatex 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 reweig
42、hing. The specimenmass 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
43、liquid and note 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
44、 of the samplewhile 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
45、.5 Alternative 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 completeD1076063coagulation takes place and the color change of the indicato
46、rcan be detected against the white background of the slightlycoagulated latex.11.6 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
47、 required, cm3, 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
48、the latex, g.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 th
49、e 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 HCl,n = volume of standard HCl required, cm3, andW = original mass of the latex, g.12. Viscosity12.1 Apparatus:12.1.1 ViscometerThe apparatus3shall consist of a syn-chronous induction-type motor capable of driving at constantrotational speeds of 0.63 and 6.3 rad/s (6 and 60 rpm) a shaftto w
