1、Designation: D465 05 (Reapproved 2010)D465 15Standard Test Methods forAcid Number of Naval StoresPine Chemical ProductsIncluding Tall Oil and Other Related Products1This standard is issued under the fixed designation D465; the number immediately following the designation indicates the year oforigina
2、l adoption or, in the case of revision, 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 U.S. Department of
3、Defense.1. Scope1.1 These test methods are intended for determining the acid number of naval storepine chemical products as defined inTerminology D804 including tall oil products, wood and gum rosin, and other related materials. These test methods may not beapplicable to all modified rosin products.
4、 Two test methods are covered, as follows:1.1.1 Potentiometric method (referee), and1.1.2 Internal indicator method (alternate).1.2 The potentiometric method is suitable for use with both light- and dark-colored products. It should be considered the refereemethod. The internal indicator method is su
5、itable for use only with light- and medium-colored products with a Gardner color ofless than 12. It should be considered the alternate method.1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.4 This standard does not purpo
6、rt to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D803 T
7、est Methods for Testing Tall OilD804 Terminology Relating to Pine Chemicals, Including Tall Oil and Related ProductsE70 Test Method for pH of Aqueous Solutions With the Glass ElectrodeE177 Practice for Use of the Terms Precision and Bias in ASTM Test MethodsE691 Practice for Conducting an Interlabor
8、atory Study to Determine the Precision of a Test Method3. Significance and Use3.1 These test methods are designed to broaden the scope of the earlier editions of the test method by the inclusion of tall oiland tall oil derived products as test materials and will be referenced in Test Methods D803.3.
9、2 The acid number is an important property of naval stores products, pine chemical products, such as tall oil, and the productsobtained by the fractionation of tall oil. It is the test method widely used to determine the total free acid content of these products.3.3 The potentiometric test method sh
10、ould be used when the most reproducible results are required.4. Preparation of Sample4.1 If the sample for analysis is rosin, it shall consist of small pieces of rosin chipped from a freshly exposed part of a lumpor lumps, and thereafter crushed to facilitate weighing and dissolution. Prepare the sa
11、mple the same day on which the test is begun,in order to avoid changes in properties due to surface oxidation. This is very pronounced on ground rosin having a large surfacearea exposed to the air. Existing rosin dust and powdered rosin must not be used.1 These test methods are under the jurisdictio
12、n of ASTM Committee D01 on Paint and Related Coatings, Materials, and Applications and are the direct responsibility ofSubcommittee D01.34 on Pine Chemicals and Hydrocarbon Resins.Current edition approved June 1, 2010Dec. 1, 2015. Published June 2010December 2015. Originally approved in 1937. Last p
13、revious edition approved in 20052010 asD465 05.D465 05 (2010). DOI: 10.1520/D0465-05R10.10.1520/D0465-15.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standard
14、sstandards Document Summary page on the ASTM website.This document 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 acc
15、urately, ASTM recommends that users consult prior editions as appropriate. 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 St
16、ates14.2 If the sample is a nonhomogenous liquid, heat the entire sample in a closed container fitted with a capillary vent or theequivalent. Some kind of agitation, even if done occasionally by hand, saves much time. Heat by immersion in open steam or hotwater bath to avoid overheating. When dealin
17、g with crystallized rosin a temperature of approximately 160C may be needed.Sampling should take place only when the entire sample is homogeneous and has been well stirred.4.3 For other products no special preparation is necessary except storage in a closed container prior to testing.D465 1524.4 Gui
18、deline for sample size, solvent, and titrant:SampleSample Size,gSolvent I,mLSolvent II,mLTitrant,KOHFatty acidsDTOARosin soap4.0 0.05 Isopropylalcohol, ormethanol100None 0.5NFA esters 20 0.1 Isopropylalcohol, ormethanol100None 0.1NRosinCTOAPitch4.0 0.05 Toluene 25 Isopropylalcohol 750.5NRosin esters
19、10 0.1 g10 0.1 Toluene 25 Isopropylalcohol 750.1NA DTO DTO represents distilled tall oil, while CTO represents crude tall oil.5. Purity of Reagents and Water5.1 Unless otherwise indicated, it is intended that all reagents shall conform to the specifications established by the Committeeon Analytical
20、Reagents of the American Chemical Society, where such specifications are available. References to water shall beunderstood to mean distilled or deionized water.3POTENTIOMETRIC METHOD (REFEREE METHOD)6. Apparatus6.1 Glass Electrode pH Meter, conforming to the requirements of Test Method E70. Use eith
21、er standard or alkali-resistantelectrodes for this test. An automatic potentiometric titrator may be used in place of a pH meter.6.2 Buret, 50 mL with 0.1 mL divisions.6.3 Stirrer, variable-speed with polytetrafluoroethylene (PTFE) coated magnetic stir bar or other type mechanical stirrer.6.4 Beaker
22、, 400-mL tall-form.7. Reagents7.1 Alkali, Standard Solution (0.5 N)Dissolve 33 g of potassium hydroxide (KOH) (pellets or sticks) in methyl alcoholconforming to 5.1, and dilute to 1 Lwith the same solvent. Standardize to 6 0.001 N by dissolving potassium acid phthalate (KHP)in 60 mL of water followe
23、d by the addition of 40 mL of isopropyl alcohol once the KHP has dissolved; 2.553 g of KHP will beneutralized by 25.0 mL of 0.5 N KOH solution. Protect the standardized solution against evaporation and absorption of carbondioxide (CO2) from the air. The solution should be standardized frequently, ei
24、ther potentiometrically or colorimetrically usingeither phenolphthalein or thymol blue as the indicator. The standardization should use the same equipment and techniques as usedin the actual acid number determination.7.2 Alkali, Standard Solution (0.1 N)Dissolve 6.6 g of potassium hydroxide (KOH) (p
25、ellets or sticks) in methyl alcoholconforming to 7.4, and dilute to 1 Lwith the same solvent. Standardize to 6 0.001 N by dissolving potassium acid phthalate (KHP)in 60 mL of water followed by the addition of 40 mL of isopropyl alcohol once the KHP has dissolved; 0.5106 g of KHP will beneutralized b
26、y 25.0 mL of 0.1 N KOH solution. Protect the standardized solution against evaporation and absorption of carbondioxide (CO2) from the air. The solution should be standardized frequently, either potentiometrically or colorimetrically usingeither phenolphthalein or thymol blue as the indicator. The st
27、andardization should use the same equipment and techniques as usedin the actual acid number determination.7.3 Isopropyl Alcohol, as in 5.1.7.4 Methyl Alcohol, as in 5.1.7.5 Toluene, as in 5.1.3 Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. Fo
28、r Suggestions on the testing of reagents not listed bythe American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and NationalFormulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.D465 1537.6 Borax Buf
29、fer, Standard Solution (0.01 M, pH 9.18 at 25C)Dissolve 3.81 6 0.01 g of disodium tetraborate (Na2B4O710H2O) in water and dilute to 1 L in a volumetric flask. Use the special grade4 of borax prepared specifically for use as a pHstandard. As an alternative, a commercially available buffer with a pH b
30、etween 9 and 11 may be used instead of self-preparedstandard.8. Standardization of Apparatus8.1 Adjust the pH meter with the standard buffer solution from 7.6, following essentially the same procedure as described inTest Method E70.9. Procedure9.1 Transfer the prescribed amount of sample recommended
31、 in 4.4, weighed to the nearest 0.001 g, to a 400-mL tall-formbeaker. Add the proper amount of solvent I (see 4.4) and swirl to dissolve. Heat gently if necessary to dissolve the sample.9.2 Add the correct amount of solvent II (see 4.4), if required, and cool to near room temperature.9.3 Adjust the
32、beaker so the lower half of each electrode of the pH meter is immersed in the solution. Start the stirrer and adjustthe speed so that there is vigorous stirring without spattering.NOTE 1Glass electrodes tend to dehydrate in nearly anhydrous solvent medium. Condition the electrode in water between te
33、sts and check with knownpH buffers frequently.9.4 Titrate with the standard alkali solution, recording the buret and pH meter readings. Sufficient alkali may be added initiallyto bring the pH of the solution to about 8.Allow sufficient time for the electrode system to reach equilibrium.Add alkali in
34、 1.0-mLportions until the change in pH per increment added amounts to about 0.3 pH unit. Reduce the additions of alkali to 0.1 mL orsmaller until the end point has been passed, as indicated by a significant decrease in pH units per 0.1 mL added. Continue thetitration with 1.0-mL portions until it be
35、comes apparent that the inflection point has been well defined.9.5 Determine the inflection point (point of maximum change in pH per millilitre of alkali solution) to the nearest 0.05 mL byplotting the pH readings against the millilitres of alkali used. For greater accuracy, a plot may be made of th
36、e change in pH permillilitre of alkali, against the pH. The peak of this curve will indicate the exact inflection point. The inflection point is consideredas the end point of the titration. Alternatively, if an automatic titrator is used, the end point is either as inflection point from theplotted c
37、urve or the pH determined to coincide with the inflection point in the laboratory performing the analysis.NOTE 2The value of 10.8 is the average pH encountered at the inflection point by the above procedure using closely controlled conditions, solvent,etc.10. Calculation and Report10.1 Calculate the
38、 acid number of the sample, expressed as milligrams of KOH per gram of sample, as follows, and report tothe nearest whole number:Acid number5A 3N 356.1!/Bwhere:A = alkali solution required for titration of the specimen, mL,N = normality of the alkali solution, andB = specimen weight, g.INTERNAL INDI
39、CATOR METHOD (ALTERNATE METHOD)11. Reagents11.1 Prepare or use, as required, the reagents described in 7.1 7.5.11.2 Phenolphthalein Indicator SolutionDissolve 1 g of phenolphthalein in 100 mL of methyl alcohol.11.3 Thymol Blue Indicator SolutionDissolve 0.1 g of thymol blue in 100 mL of methyl alcoh
40、ol.12. Apparatus12.1 Same apparatus as 6.2 and 6.3.12.2 Erlenmeyer flask, 250-mL.13. Procedure13.1 Transfer the prescribed amount of sample recommended in 4.4, weighed to the nearest 0.001 g, to a 250-mL Erlenmeyerflask. Add the proper amount of solvent I (see 4.4) and swirl to dissolve. Heat gently
41、 if necessary to dissolve.4 The National Institute for Standards and Testing standard sample of borax No. 187 is satisfactory for this purpose.D465 15413.2 Add the correct amount of solvent II (see 4.4) if required and cool to near room temperature.13.3 Titrate the solution with the standard alkali
42、solution using 4 to 5 drops of either phenolphthalein or thymol blue indicatorsolution. Dark colored samples may require additional indicator to be added to the solution. With phenolphthalein titrate to the firstpersistent faint pink color, or with thymol blue titrate to a blue-green color. Read bur
43、et to 0.05-mL titrant.NOTE 3If less than 20 mL of titrant is consumed the sample size should be increased.14. Calculation and Report14.1 Calculate the acid number as described in Section 10 and report to the nearest whole number.15. Precision and Bias15.1 Interlaboratory Test ProgramAn interlaborato
44、ry study of the acid number of three substances, tall oil fatty acids, distilledtall oil, and rosin, was run in 1994. Each of 14 laboratories tested each of the three materials. The design of the experiment, similarto that of Practice E691 and a within-between analysis of the data are given in ASTM
45、Research Report.515.2 Test ResultThe precision information given below for the acid number of naval storespine chemical products is for thecomparison of two test results, each of which is the average of three test determinations as follows:15.2.1 Repeatability Limit, 95 % (within laboratory) = 1.2.1
46、5.2.2 Reproducibility Limit, 95 % (between laboratories) = 3.3.15.3 These terms (repeatability limit and reproducibility limit) are used as specified in Practice E177. The respective standarddeviations among test results, related to the above numbers by the factor of 2.8, are as follows:15.3.1 Repea
47、tability standard deviation = 0.4.15.3.2 Reproducibility standard deviation = 1.2.15.4 BiasThese test methods have no bias because acid number is defined only in terms of these test methods.16. Keywords16.1 acid number; rosin; tall oil; tall oil fatty acidsASTM International takes no position respec
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49、ndard 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 revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Commi
