1、Designation: D 465 05Standard Test Methods forAcid Number of Naval Stores Products Including Tall Oiland Other Related Products1This standard is issued under the fixed designation D 465; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisi
2、on, 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 These test methods a
3、re intended for determining the acidnumber of naval store products as defined in TerminologyD 804 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 follows:1.1.1 Poten
4、tiometric 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 medium-colored prod
5、ucts 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 any, associate
6、d 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:2D 803 Test Methods for Testing Tall OilD 804 Terminology Relat
7、ing to Naval Stores, Including TallOil and Related ProductsE70 Test Method for pH of Aqueous Solutions With theGlass ElectrodeE 177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3.
8、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 D 803.3.2 The acid number is an important property of naval storesp
9、roducts, 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 Sample4.1 If th
10、e 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 due tosurfa
11、ce 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. Some kin
12、d 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 homogeneous and has
13、 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 of Subcom
14、mittee D01.34 on Naval Stores.Current edition approved Dec. 1, 2005. Published January 2006. Originallyapproved in 1937. Last previous edition approved in 2001 as D 465 01.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For An
15、nual 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 sample size, solvent, and titrant:SampleSample Size,gSol
16、vent 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 0.1 g10 6 0.1 Toluene 25 Isopropylalcohol 750.1N_ADTO re
17、presents 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 Reagents of the American ChemicalSociety, where such specifi
18、cations 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 standard or alkali-resistant electrodes for this test. An
19、 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 tall-form.7. Reagents7.1 Alkali, Standard Solution (0
20、.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 addition of40 mL of isopropyl alcohol once the KHP has
21、 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 potentio-metrically or colorimetrically using either phenolph
22、thalein 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 sticks) in methylalcohol conforming to 7.4, and dilute to
23、 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 0.1 N KOHsolution. Protect the standardized solution ag
24、ainst 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 should usethe same equipment and techniques as used in
25、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 dilute to 1 L in a volumetricflask. Use the special gr
26、ade4of 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 standard buffer solutionfrom 7.6, following essentiall
27、y 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 swirlto dissolve. Heat gently if necessary to dissolve the s
28、ample.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 that there is vigorous stirring withoutspattering.NOT
29、E 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 readings. Sufficient alkali may be addedinitially to bring
30、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 smaller until the end point hasbeen passed, as indica
31、ted 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 Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorse
32、t, 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.D465052per 0.1 mL added. Continue the titration with 1.0-mL p
33、ortionsuntil 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 the millilitres ofalkali used. For greater accuracy, a plot ma
34、y 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 titrator is used, the end point iseither as inflection point from
35、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 controlled condi-tions, solvent, etc.10. Calculation and Report10.1
36、 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,mLN = normality of the alkali solution, andB = specimen weight,
37、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 Indicator SolutionDissolve 0.1 g ofthymol blue in 100 mL of meth
38、yl 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 proper amount of solvent I (see 4.4)and swirl to dissolve. Hea
39、t 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 thymol blueindicator solution. Dark colored samples may require
40、 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 titrant is consumed the sample sizeshould be increased.14. Calculati
41、on 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 fatty acids,distilled tall oil, and rosin, was run in 1994. Eac
42、h of 14laboratories tested each of the three materials. The design ofthe experiment, similar to that of Practice E 691 and awithin-between analysis of the data are given in ASTMResearch Report.515.2 Test ResultThe precision information given belowfor the acid number of naval stores products is for t
43、hecomparison 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 terms (repeatability limit and reproducibilitylimit) are used a
44、s specified in Practice E 177. 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 = 1.2.15.4 BiasThese test methods have no bias because acidnum
45、ber is defined only in terms of these test methods.16. Keywords16.1 acid number; rosin; tall oil; tall oil fatty acids5Supporting data are available from ASTM International Headquarters. RequestRR:D011086.D465053ASTM International takes no position respecting the validity of any patent rights assert
46、ed 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 infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by t
47、he 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
48、 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 Committee on Standards, at the address shown below.This standard is copyrighted by ASTM Interna
49、tional, 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).D465054
