1、Designation: D465 05 (Reapproved 2010)Standard Test Methods forAcid Number of Naval Stores Products Including Tall Oiland Other Related Products1This standard is issued under the fixed designation D465; the number immediately following the designation indicates the year oforiginal adoption or, in th
2、e 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 Department of Defense.1. Scope1.1 These
3、 test methods are intended for determining the acidnumber of naval store products as defined in TerminologyD804 including tall oil products, wood and gum rosin, andother related materials. These test methods may not be appli-cable to all modified rosin products. Two test methods arecovered, as follo
4、ws:1.1.1 Potentiometric method (referee), and1.1.2 Internal indicator method (alternate).1.2 The potentiometric method is suitable for use with bothlight- and dark-colored products. It should be considered thereferee method. The internal indicator method is suitable foruse only with light- and mediu
5、m-colored products with aGardner color of less than 12. It should be considered thealternate method.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.4 This standard does not purport to address all of thesafety concerns, if
6、any, associated with its use. It 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:2D803 Test Methods for Testing Tall OilD804 Termi
7、nology Relating to Naval Stores, Including TallOil and Related ProductsE70 Test Method for pH of Aqueous Solutions With theGlass ElectrodeE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test
8、 Method3. Significance and Use3.1 These test methods are designed to broaden the scope ofthe earlier editions of the test method by the inclusion of tall oiland tall oil derived products as test materials and will bereferenced in Test Methods D803.3.2 The acid number is an important property of nava
9、l storesproducts, tall oil, and the products obtained by the fractionationof tall oil. It is the test method widely used to determine thetotal free acid content of these products.3.3 The potentiometric test method should be used when themost reproducible results are required.4. Preparation of Sample
10、4.1 If the sample for analysis is rosin, it shall consist ofsmall pieces of rosin chipped from a freshly exposed part of alump or lumps, and thereafter crushed to facilitate weighingand dissolution. Prepare the sample the same day on which thetest is begun, in order to avoid changes in properties du
11、e tosurface oxidation. This is very pronounced on ground rosinhaving a large surface area exposed to the air. Existing rosindust and powdered rosin must not be used.4.2 If the sample is a nonhomogenous liquid, heat the entiresample in a closed container fitted with a capillary vent or theequivalent.
12、 Some kind of agitation, even if done occasionallyby hand, saves much time. Heat by immersion in open steam orhot water bath to avoid overheating. When dealing withcrystallized rosin a temperature of approximately 160C maybe needed. Sampling should take place only when the entiresample is homogeneou
13、s and has been well stirred.4.3 For other products no special preparation is necessaryexcept storage in a closed container prior to testing.1These test methods are under the jurisdiction of ASTM Committee D01 onPaint and Related Coatings, Materials, and Applications and are the directresponsibility
14、of Subcommittee D01.34 on Pine Chemicals and HydrocarbonResins.Current edition approved June 1, 2010. Published June 2010. Originallyapproved in 1937. Last previous edition approved in 2005 as D465 05. DOI:10.1520/D0465-05R10.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orco
15、ntact 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, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.4 Guideline for sa
16、mple size, solvent, and titrant:SampleSample Size,gSolvent I,mLSolvent II,mLTitrant,KOHFatty acidsDTOARosin soap4.0 6 0.05 Isopropylalcohol, ormethanol100None 0.5NFA esters 20 6 0.1 Isopropylalcohol, ormethanol100None 0.1NRosinCTOAPitch4.0 6 0.05 Toluene 25 Isopropylalcohol 750.5NRosin esters10 6 0.
17、1 g10 6 0.1 Toluene 25 Isopropylalcohol 750.1N_ADTO 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 re-agents shall conform to the specifications established by theCommittee on Analytical Reagen
18、ts of the American ChemicalSociety, where such specifications are available. References towater shall be understood to mean distilled or deionized water.3POTENTIOMETRIC METHOD (REFEREE METHOD)6. Apparatus6.1 Glass Electrode pH Meter, conforming to the require-ments of Test Method E70. Use either sta
19、ndard or alkali-resistant electrodes for this test. An automatic potentiometrictitrator 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 mechanicalstirrer.6.4 Beaker, 400-mL
20、 tall-form.7. Reagents7.1 Alkali, Standard Solution (0.5 N)Dissolve 33 g ofpotassium hydroxide (KOH) (pellets or sticks) in methylalcohol conforming to 5.1, and dilute to 1 L with the samesolvent. Standardize to 6 0.001 N by dissolving potassium acidphthalate (KHP) in 60 mL of water followed by the
21、addition of40 mL of isopropyl alcohol once the KHP has dissolved; 2.553g of KHP will be neutralized by 25.0 mL of 0.5 N KOHsolution. Protect the standardized solution against evaporationand absorption of carbon dioxide (CO2) from the air. Thesolution should be standardized frequently, either potenti
22、o-metrically or colorimetrically using either phenolphthalein orthymol blue as the indicator. The standardization should usethe same equipment and techniques as used in the actual acidnumber determination.7.2 Alkali, Standard Solution (0.1 N)Dissolve 6.6 g ofpotassium hydroxide (KOH) (pellets or sti
23、cks) in methylalcohol conforming to 7.4, and dilute to 1 L with the samesolvent. Standardize to 6 0.001 N by dissolving potassium acidphthalate (KHP) in 60 mL of water followed by the addition of40 mL of isopropyl alcohol once the KHP has dissolved;0.5106 g of KHP will be neutralized by 25.0 mL of 0
24、.1 N KOHsolution. Protect the standardized solution against evaporationand absorption of carbon dioxide (CO2) from the air. Thesolution should be standardized frequently, either potentio-metrically or colorimetrically using either phenolphthalein orthymol blue as the indicator. The standardization s
25、hould usethe same equipment and techniques as used in the actual acidnumber determination.7.3 Isopropyl Alcohol,asin5.1.7.4 Methyl Alcohol,asin5.1.7.5 Toluene,asin5.1.7.6 Borax Buffer, Standard Solution (0.01 M, pH 9.18 at25C)Dissolve 3.81 6 0.01 g of disodium tetraborate(Na2B4O710H2O) in water and
26、dilute to 1 L in a volumetricflask. Use the special grade4of borax prepared specifically foruse as a pH standard. As an alternative, a commerciallyavailable buffer with a pH between 9 and 11 may be usedinstead of self-prepared standard.8. Standardization of Apparatus8.1 Adjust the pH meter with the
27、standard buffer solutionfrom 7.6, following essentially the same procedure as de-scribed in Test Method E70.9. Procedure9.1 Transfer the prescribed amount of sample recommendedin 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 swirlt
28、o dissolve. Heat gently if necessary to dissolve the sample.9.2 Add the correct amount of solvent II (see 4.4), ifrequired, and cool to near room temperature.9.3 Adjust the beaker so the lower half of each electrode ofthe pH meter is immersed in the solution. Start the stirrer andadjust the speed so
29、 that there is vigorous stirring withoutspattering.NOTE 1Glass electrodes tend to dehydrate in nearly anhydroussolvent medium. Condition the electrode in water between tests and checkwith known pH buffers frequently.9.4 Titrate with the standard alkali solution, recording theburet and pH meter readi
30、ngs. Sufficient alkali may be addedinitially to bring the pH of the solution to about 8. Allowsufficient time for the electrode system to reach equilibrium.Add alkali in 1.0-mL portions until the change in pH perincrement added amounts to about 0.3 pH unit. Reduce theadditions of alkali to 0.1 mL or
31、 smaller until the end point hasbeen passed, as indicated by a significant decrease in pH units3Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For Suggestions on the testing of reagents notlisted by the American Chemical Society, see Annual Sta
32、ndards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.4The National Institute for Standards and Testing standard sample of borax No.187 is satisfactory for this purpose.D465 05
33、 (2010)2per 0.1 mL added. Continue the titration with 1.0-mL portionsuntil it becomes apparent that the inflection point has been welldefined.9.5 Determine the inflection point (point of maximumchange in pH per millilitre of alkali solution) to the nearest0.05 mL by plotting the pH readings against
34、the millilitres ofalkali used. For greater accuracy, a plot may be made of thechange in pH per millilitre of alkali, against the pH. The peakof this curve will indicate the exact inflection point. Theinflection point is considered as the end point of the titration.Alternatively, if an automatic titr
35、ator is used, the end point iseither as inflection point from the plotted curve or the pHdetermined to coincide with the inflection point in the labora-tory performing the analysis.NOTE 2The value of 10.8 is the average pH encountered at theinflection point by the above procedure using closely contr
36、olled condi-tions, solvent, etc.10. Calculation and Report10.1 Calculate the acid number of the sample, expressed asmilligrams of KOH per gram of sample, as follows, and reportto the nearest whole number:Acid number 5 A 3 N 3 56.1!/Bwhere:A = alkali solution required for titration of the specimen,mL
37、N = normality of the alkali solution, andB = specimen weight, g.INTERNAL INDICATOR METHOD (ALTERNATEMETHOD)11. Reagents11.1 Prepare or use, as required, the reagents described in7.1-7.5.11.2 Phenolphthalein Indicator SolutionDissolve1gofphenolphthalein in 100 mL of methyl alcohol.11.3 Thymol Blue In
38、dicator SolutionDissolve 0.1 g ofthymol blue in 100 mL of methyl alcohol.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 recom-mended in 4.4, weighed to the nearest 0.001 g, to a 250-mLErlenmeyer flask. Add the
39、proper amount of solvent I (see 4.4)and swirl to dissolve. Heat gently if necessary to dissolve.13.2 Add the correct amount of solvent II (see 4.4)ifrequired and cool to near room temperature.13.3 Titrate the solution with the standard alkali solutionusing 4 to 5 drops of either phenolphthalein or t
40、hymol blueindicator solution. Dark colored samples may require addi-tional indicator to be added to the solution. With phenolphtha-lein titrate to the first persistent faint pink color, or with thymolblue titrate to a blue-green color. Read buret to 0.05-mL titrant.NOTE 3If less than 20 mL of titran
41、t is consumed the sample sizeshould be increased.14. Calculation and Report14.1 Calculate the acid number as described in Section 10and report to the nearest whole number.15. Precision and Bias15.1 Interlaboratory Test ProgramAn interlaboratorystudy of the acid number of three substances, tall oil f
42、atty acids,distilled tall oil, and rosin, was run in 1994. Each of 14laboratories tested each of the three materials. The design ofthe experiment, similar to that of Practice E691 and a within-between analysis of the data are given in ASTM ResearchReport.515.2 Test ResultThe precision information gi
43、ven belowfor the acid number of naval stores products is for thecomparison of two test results, each of which is the average ofthree test determinations as follows:15.2.1 Repeatability Limit, 95 % (within laboratory) = 1.2.15.2.2 Reproducibility Limit, 95 % (between laborato-ries) = 3.3.15.3 These t
44、erms (repeatability limit and reproducibilitylimit) are used as specified in Practice E177. The respectivestandard deviations among test results, related to the abovenumbers by the factor of 2.8, are as follows:15.3.1 Repeatability standard deviation = 0.4.15.3.2 Reproducibility standard deviation =
45、 1.2.15.4 BiasThese test methods have no bias because acidnumber is defined only in terms of these test methods.16. Keywords16.1 acid number; rosin; tall oil; tall oil fatty acids5Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D
46、01-1086.D465 05 (2010)3ASTM 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 validity of any such patent rights, and the riskof infringem
47、ent of such rights, are entirely their own responsibility.This standard 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
48、 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 kn
49、own to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).D465
