1、Designation: D1076 14D1076 15Standard 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 re
2、vision, 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.1. Scope1.1 This specification covers requirements for first grade concentrated natural rubber latex (see Tabl
3、e 1) of the followingcategories:Category 1Centrifuged Hevea natural latex preserved with ammonia only or by formaldehyde followed by ammonia.Category 2Creamed Hevea natural latex preserved with ammonia only or by formaldehyde followed by ammonia.Category 3Centrifuged Hevea natural latex preserved wi
4、th low ammonia with other necessary preservatives.Category 4Centrifuged, or centrifuged and creamed, guayule latex, or other natural rubber latex, containing less than 200 gtotal protein per gram dry weight of latex, with ammonia or other hydroxide, with other necessary preservatives and stabilizers
5、.Category 5Centrifuged Hevea natural latex treated with aluminum hydroxide or by other means, preserved with ammoniaonly or by formaldehyde followed by ammonia containing less than 0.5 % non-rubber content.1.2 This specification is not necessarily applicable to latices prepared or preserved by other
6、 methods, and shall not be construedas limiting the desirability or usefulness of other categories of latices. It does apply to natural latex sources other than Heveabrasiliensis but does not apply to compounded latex concentrates.1.3 The analytical procedures applicable to the specifications are in
7、cluded and appear in the following order:SectionSampling 6 and 7Total Solids 81 This specification is under the jurisdiction of ASTM Committee D11 on Rubber and is the direct responsibility of Subcommittee D11.22 on Natural Rubber.Current edition approved July 1, 2014Dec. 15, 2015. Published Decembe
8、r 2014January 2016. Originally approved in 1949. Last previous edition approved in 20102014as D1076 10.D1076 14. DOI: 10.1520/D1076-14.10.1520/D1076-15.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.
9、3Dry rubber content (DRC),A min, % 59.8 64.0 59.8 42.0 60.8Total 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
10、min 0.29 max 0.60 min 0.60 minOr: total alkalinity calculated 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, maxB 0.80 0.80 0.80 0.80 0.8Mechanical stability, s, min 650 650 650 90 650Copper content, max, % of t
11、otal solids 0.0008 0.0008 0.0008 0.0008 0.0008Manganese content, max, % of total sol-ids0.0008 0.0008 0.0008 0.0008 0.0008Color on visual inspection no pronounced blue or grayCOdor after neutralization with boric acid no putrefactive odorA Dry rubber content by definition and use is the acid coagula
12、ble portion of latex after washing and drying.B It 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.C Blue or gray color usually denotes iron contamination caused by improper storage in containers.This docum
13、ent is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as a
14、ppropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1Dry Rubber Content 9Protein Content 10Total Alkalinity 11V
15、iscosity 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 the standard. The values given in pa
16、rentheses are for information only.2. Referenced Documents2.1 ASTM Standards:2D1278 Test Methods for Rubber from Natural SourcesChemical AnalysisD4483 Practice for Evaluating Precision for Test Method Standards in the Rubber and Carbon Black Manufacturing IndustriesD5712 Test Method for Analysis of
17、Aqueous Extractable Protein in Latex, Natural Rubber, and Elastomeric Products Using theModified Lowry MethodD6499 Test Method for The Immunological Measurement of Antigenic Protein in Natural Rubber and its ProductsE70 Test Method for pH of Aqueous Solutions With the Glass Electrode3. General Speci
18、fication Requirements3.1 In manufacturing, the material shall be processed in accordance with the best commercial practice and shall be of uniformcomposition.3.2 The material shall conform to the chemical and physical requirements prescribed in Table 1.4. Significance and Use4.1 This specification d
19、enotes limits on the 4 categories of latex as defined in the scope and defines the test methods to use forthe specified properties. These test methods may be used for production control or for referee purposes.5. Inspection5.1 Inspection of the material shall be made as agreed upon between the purch
20、aser and the seller as part of the purchase contract.SAMPLING AND METHODS OF TESTING6. Preparations for Sampling6.1 Drums:6.1.1 Open-Head DrumsThe top shall be removed and the contents stirred with a high-speed stirrer for 10 min.6.1.2 Closed-Head DrumsIf the drum has at least 2 % air space, which i
21、s 20 mm (0.75 in.) on a standard drum, lay it on itsside and roll for not less than 10 min. Up end the drum to its original position and allow to stand for 15 min and then repeat therolling operation for at least a further 10 min. In the case of drums with less than 2 % air space, all of the latex i
22、n the closed-headdrum shall be transferred to a larger vessel and mixed with a high-speed stirrer for 10 min.6.2 Tank CarsSamples shall be taken from the top and bottom of the car. If the total solids in the top and bottom samples agreewithin 0.5 %, the car shall be considered uniform enough for sam
23、pling. If top and bottom samples do not agree within 0.5 %, thecontents of the car shall be agitated until samples taken from the top and bottom do agree on total solids within 0.5 %.7. Sampling7.1 DrumsAfter preparations for sampling, sample without delay. A suitable method is by slowly inserting a
24、 clean, dry glasstube of 10 to 15 mm internal diameter and open at both ends, until it reaches the bottom of the container. Then close the upperend of the tube and transfer the contents to a clean, dry sample bottle. Repeat the operation until sufficient latex has been obtained.Alternatively, a spec
25、ially constructed metal sampling tube may be used, the bottom of which can be closed by remote control. Nocopper or brass shall be used in any part of its construction. At least 10 % of the drums in a shipment shall be sampled.2 For referencedASTM standards, visit theASTM website, www.astm.org, or c
26、ontactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.D1076 1527.2 Tank CarsSeparate samples of at least 475 cm3 each shall be taken from the top, center, and bottom of the tank car. Taket
27、he top sample first, then the center sample, and the bottom sample last. Use a weighted sampler with a remotely operatedremovable top, or other suitable sampling device that will accomplish the same results. Blend the three samples thoroughly. Eachsample shall be poured immediately into a tightly st
28、oppered container. The three samples shall be combined and thoroughlyblended into a composite sample. At least 950 cm3 of this composite sample shall be used for test. One composite sample onlyis required from each tank car.8. Total Solids8.1 ApparatusTared, covered, flat-bottom weighing dish approx
29、imately 60 mm (2.5 in.) in diameter, which may be made ofglass, tinned metal, or aluminum.8.2 ReagentDistilled water.8.3 ProcedureWeigh 2.5 6 0.5 g of the latex to the nearest 1 mg in the tared, covered weighing dish. Remove the cover anddistribute the latex over the bottom of the dish over an area
30、of approximately 32 cm2 (5 in.2). This may be facilitated by carefullyadding approximately 1 cm3 of distilled water to the latex and gently swirling the dish. With the dish uncovered, dry the specimenin a vented air oven for 16 h at 70 6 2C or 2 h at 100 6 2C. Replace the cover, cool in a desiccator
31、 to room temperature, andweigh. Repeat drying and weighing until the mass is constant to 1 mg or less. Tests shall be run in duplicate and shall check within0.15 %. The average of the two determinations shall be taken as the result.8.4 CalculationsCalculate the percentage of total solids as follows:
32、Total solids,%5C 2A!/B 2A!# 3100 (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 Content9.1 ApparatusPorcelain evaporating dish approximately 100 mm in diameter and 50 mm deep.9.2 ReagentAcetic
33、 acid aqueous solution (20 Mg/m3).9.3 Weigh approximately 10 g of the latex to the nearest 1 mg into a porcelain evaporating dish, and add distilled water untilthe total solids content is approximately 25 %. Add sufficient acetic acid (2 %), while stirring constantly over a 5-min period, tocoagulate
34、 completely the latex (80 cm3 should be sufficient). Category 4 guayule latex may also require the addition of up to 20mL hydrochloric acid (2 %) to complete its coagulation.9.3.1 Place the dish on a steam bath and leave undisturbed for 15 to 30 min. A clear serum should result, and 30 min is themax
35、imum time allowed. If the serum is milky, the acid was either added too fast or in insufficient amount and the procedure shouldbe repeated until a clear serum results. Pick up coagulated latex particles with the main body of the coagulum. Wash coagulumin running water and pass between rolls. Repeat
36、this process 5 times and reduce the sheet of coagulated rubber to a maximumthickness of 2 mm and dry at 70 6 2C in a vented air oven atmosphere. If oxidation occurs, the test may be run with the optionof using a drying temperature of 55 6 2C, or an antioxidant may be added to the latex before coagul
37、ation. If polymer oxidationoccurs, the test may be rerun with the option of using a drying temperature of 55 6 2C. Cool in a desiccator to room temperatureand weigh. Repeat drying and weighing until the mass is constant to 1 mg or less.9.4 Duplicate samples shall be run and shall check within 0.2 %.
38、 The average of the two determinations shall be taken as theresult.9.5 CalculationCalculate the dry rubber content as follows:Dry rubber content,%5mass of dry coagulum/mass of sample3100 (2)10. Protein Content10.1 Total ProteinSolubilize latex proteins in 1 % SDS and 50 mM sodium phosphate buffer (f
39、inal concentration) and thenquantify using the modified Lowry test according to Test Method D5712.10.1.1 Solubilization MethodMix latex sample (500 l) with 450 l 100 mM sodium phosphate buffer (1:1) into threemicrofuge tubes for each sample; add 50 l 20 % SDS into each tube, mix; incubate at 25C for
40、 2 h with shaking at 200 rpm; spinfor 5 min, remove rubber pad; transfer aqueous phase into new tubes and spin again to clarify; divide each sample into 3 0.6mL tubes for each sample (these can be stored at 4C overnight); prepare bovine serum albumin standards in extraction buffer at0, 5, 10, 15, 25
41、, 50, 100, 200, 300, and 400 gmL; add 60 l 1.5 mg/mL sodium deoxycholate to samples and standards, mix,stand for 10 min; add 120 l of 72 % freshly mixed trichloroacetic acid and phosphotungstic acid (1:1) into each sample, mix,incubate for 30 min at RT; spin 15 min at 6000 xg, remove supernatant, ai
42、r dry pellet; suspend each pellet in 250 l 0.2 M sodiumhydroxide and store at 4C until assayed; assay within 24 h using the modified Lowry test according to Test Method D5712.D1076 15310.2 Hevea Antigenic ProteinSolubilize latex proteins with 1 % SDS and 50 mM sodium phosphate buffer (finalconcentra
43、tion) then quantify using the antigenic protein assay according to Test Method D6499.11. Total Alkalinity11.1 ApparatusGlass electrode pH meter.11.2 Reagent0.1 mol standard HCl.11.3 Preparation of SpecimenPlace approximately 5 g of latex into a glass weighing bottle of approximately 10-cm3 capacity,
44、having a ground glass cap, and weigh to the nearest 1 mg. Pour the specimen into a beaker containing approximately 300 cm3 ofdistilled water, restopper quickly to prevent loss of ammonia, and set aside for reweighing. The specimen mass is equal to thedifference between the two weighings. The transfe
45、r of the sample to the beaker shall be done in such a way that no latex runs downthe outside of the weighing bottle.11.4 Recommended ProcedureInsert the electrodes of a calibrated glass electrode pH meter into the liquid and note the pH.The meter should be calibrated and the pH measurements made in
46、accordance with Test Method E70, and the directions given bythe manufacturer of the meter. Slowly, and while stirring constantly, add 0.1 mol HCl until a pH of 6.0 is reached. Too rapidaddition or inadequate stirring of the sample while the acid is being added may cause local coagulation of the rubb
47、er. With samplesof unknown alkalinity, it is recommended that the acid be added in 1-cm3 increments, and a pH reading taken 10 s after eachaddition. As the pH of 6.0 is approached, smaller increments should be added.11.5 Alternative ProcedurePrepare the sample as described in 11.3. Add 6 drops of a
48、0.10 % alcoholic solution of methyl redand titrate with approximately 0.1 mol HCl until the indicator turns pink. The end point occurs before complete coagulation takesplace and the color change of the indicator can be detected against the white background of the slightly coagulated latex.11.6 Calcu
49、lationCalculate the total alkalinity, reported as NH3 based on grams of NH3 per 100 g of latex as follows:Total alkalinity,as NH3!%51.73M 3n!/W (3)where:M = mole of the standard HCl,n = volume of standard HCl required, cm3, andW = original mass of the latex, g.11.6.1 If total alkalinity is wanted as KOH, the following calculation applies to both procedures:Total alkalinity,as KOH!%55.613M 3n!/W (4)where:M = mole of the standard HCl,n = volume of standard HCl required, cm3, andW = original mass of the latex, g.11.6.2 If
