1、Designation: D 2165 94 (Reapproved 2006)Standard Test Method forpH of Aqueous Extracts of Wool and Similar Animal Fibers1This standard is issued under the fixed designation D 2165; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, th
2、e 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 test method covers th
3、e determination of the pH ofaqueous extracts from wool and similar animal fibers. It isapplicable to fibers in any conditionraw wool, scoured wool,sliver, top, yarn, or fabric.1.2 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsib
4、ility 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. For specificprecautionary statements, see Section 11.2. Referenced Documents2.1 ASTM Standards:2D 123 Terminology Relating to TextilesD 25
5、25 Practice for Sampling Wool for MoistureE70 Test Method for pH of Aqueous Solutions With theGlass Electrode3. Terminology3.1 Definitions:3.1.1 aqueous extract, n in wool testing, the solutionobtained by digesting a material with water or with a sodiumchloride solution to dissolve soluble materials
6、.3.1.2 pH, nin common usage, a measure of acidity oralkalinity of a solution, on a logarithmic scale, with neutralityrepresented by a value of seven, with increasing acidityrepresented by decreasingly smaller values, and with increas-ing alkalinity represented by increasingly larger values.3.1.2.1 D
7、iscussionFor a technical discussion of pH, in-cluding such phenomena as the effect of temperature on pH,see any recognized chemistry text. The pH of textiles isgenerally determined on aqueous extracts of the textile beingtested.3.1.3 For definitions of other textile terms used in this testmethod, se
8、e Terminology D 123.4. Summary of Test Method4.1 An extract is prepared using distilled water or 0.1 Nsodium chloride solution at the boil under reflux, or at roomtemperature with agitation. The pH of the extract is measuredelectrometrically with a glass electrode.5. Significance and Use5.1 The pH v
9、alues of the extracts give an indication of theacidity or alkalinity of the fiber and its water-soluble impuri-ties. These values are useful in indicating previous processingand in anticipating subsequent performance. For particularpurposes, the pH of an extract prepared by one method may bea more i
10、nformative index than another and as a consequencefour optional extraction procedures are included.5.2 This test method is not recommended for acceptancetesting because the between-laboratory precision is relativelypoor. In some cases, the purchaser and the seller may have totest a commercial shipme
11、nt of one or more specific materialsby the best available method, even though the method has notbeen recommended for acceptance testing of commercialshipments. In such a case, if there is disagreement arising fromdifferences in values reported by the purchaser and the sellerwhen using this method fo
12、r acceptance testing, the statisticalbias, if any, between the laboratory of the purchaser and thelaboratory of the seller should be determined, with eachcomparison being based on testing specimens randomly drawnfrom one sample of material of the type being evaluated.6. Apparatus and Materials6.1 Al
13、l glassware coming in contact with the liquid shall beof a chemical-resistant glass,3in which the contacting surfaceshave been soaked for two days in 0.1 N hydrochloric acid andthen rinsed thoroughly with distilled water (see 7.1) until therinsings have a pH of 6.0 or higher.NOTE 1It is desirable bu
14、t not mandatory that the glassware bereserved for extraction tests only and be filled with distilled water duringstorage between tests.1This test method is under the jurisdiction ofASTM Committee D13 on Textilesand is the direct responsibility of Subcommittee D13.13 on Wool and Felt.Current edition
15、approved Aug. 15, 2006. Published October 2006. Originallyapproved in 1961. Last previous edition approved in 2000 as D 2165 94(2000).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume info
16、rmation, refer to the standards Document Summary page onthe ASTM website.3Borosilicate glass has been found satisfactory.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.2 Apparatus for Extraction at Room Temperature:6.2.1 Erlenmeye
17、r Flasks, 250-ml, wide-mouth, withground-glass stoppers.6.2.2 Laboratory Shaker or Agitator, with apparatus forattaching the flasks, holding at least three flasks, to provideagitation that will not raise the temperature more than 5.5C in2h.6.3 Additional Equipment Needed for Extraction at TheBoil:6.
18、3.1 Erlenmeyer Flask, 500-mL, with ground-glass joint.6.3.2 Air Condenser, Glass, reflux, to fit the flask.6.3.3 Tube, to hold absorbent for acidic and basic gases.6.3.4 Glass Stopper, for flask, equipped with a stopcock andthermometer with a range from 0 to 105C.6.4 pH Meter and Glass Electrode, co
19、nforming to therequirements of Sections 5 and 6 of Test Method E70.7. Reagents7.1 Distilled Water, having a pH of between 6.2 and 7.0. Ifnot in that range of pH, redistillation is necessary.7.2 Sodium Chloride, Standard Solution (0.1 N), preparedfrom reagent grade sodium chloride (NaCl) and distille
20、d waterhaving a pH of between 6.2 and 7.0.7.3 Anhydrous Calcium Sulfate or Equivalent Absorbent forAcid or Alkaline Gases.8. Sampling and Specimen Preparation8.1 Take a lot sample of raw wool, scoured wool, sliver, top,yarn, or fabrics as specified in the sampling procedure inPractice D 2525.8.2 Sel
21、ect specimens at random from the unconditionedsample, each weighing 10 6 0.1 g. Cut the fibers of thespecimen into lengths of about 5 mm and blend.9. Number of Specimens9.1 Take a number of specimens per laboratory samplingunit such that the user can expect at the 95 % probability levelthat the test
22、 result for a laboratory sampling unit will be nomore than 0.5 percentage points above or below the trueaverage for the laboratory sampling unit as follows:9.1.1 Reliable Estimate of sWhen there is a reliableestimate of s based upon extensive past records in the userslaboratory as directed in the te
23、st method, calculate the requirednumber of specimens per laboratory sampling unit using Eq 1:n 5 ts/E!2(1)where:n = number of specimens per laboratory sampling unit(rounded upward to a whole number),s = reliable estimate of the standard deviation of individualobservations on similar materials in the
24、 users labora-tory under conditions of single operator precision,t = value of Students t for two-sided limits, a 95 %probability level, and the degrees of freedom associ-ated with the estimate of v (Table 1), andE = 0.5 percentage points, the allowable variation.9.1.2 No Reliable Estimate of sWhen t
25、here is no reliableestimate of s for the users laboratory, Eq 1 should not be useddirectly. Instead, specify the fixed numbers of specimensshown in Table 2. These numbers of specimens are calculatedusing values of s which are listed in Table 2 and which aresomewhat larger values of s than are usuall
26、y found in practice.When a reliable estimate of s for the users laboratory becomesavailable, Eq 1 will usually require fewer specimens than arelisted in Table 2.10. Preparation of Extracts10.1 Extraction with Boiling Water Include an approxi-mately proportionate quantity of any fallout present in ea
27、chspecimen. Transfer each specimen to a separate flask. Coverthe fibers with 200 mL of boiling water (see 7.1). Connect thereflux condenser, making certain that anhydrous calcium sul-fate absorbent is in the absorption tube. Shake, to completewetting of the fiber, and heat gently to maintain boiling
28、.Agitatethe solution every 10 min by shaking the apparatus. After 30 to35 min, remove the flask from the heat source, remove thereflux condenser, and stopper the flasks as quickly as possiblewith a stopper containing a thermometer. Cool the flask andcontents in water maintained at 21 6 2C, without r
29、emovingthe stopper. Measure the pH within 10 min after extraction andcooling have been completed, as directed in Section 11.10.2 Extraction with Water at Room TemperatureTake thetwo specimens, including an approximately proportionatequantity of any fallout present. Transfer each specimen to aseparat
30、e flask. Cover the fibers with 100 mL of neutral distilledwater at 21C. Then stopper the flask using a glass stopperhaving a built-in thermometer. Shake vigorously by hand forabout 30 s to wet the specimen thoroughly and then agitatemechanically for2hatarate that will not warm the solutionabove 28C.
31、 Measure the pH as directed in Section 11.TABLE 1 Values of Students t for One-Sided and Two-SidedLimits and the 95 % ProbabilityAdfOne-SidedTwo-SideddfOne-SidedTwo-SideddfOne-SidedTwo-Sided1 6.314 12.706 11 1.796 2.201 22 1.717 2.0742 2.920 4.303 12 1.782 2.179 24 1.711 2.0643 2.353 3.182 13 1.771
32、2.160 26 1.706 2.0564 2.132 2.776 14 1.761 2.145 28 1.701 2.0485 2.015 2.571 15 1.753 2.131 30 1.697 2.0426 1.943 2.447 16 1.746 2.120 40 1.684 2.0217 1.895 2.365 17 1.740 2.110 50 1.676 2.0098 1.860 2.306 18 1.734 2.101 60 1.671 2.0009 1.833 2.262 19 1.729 2.093 120 1.658 1.98010 1.812 2.228 20 1.7
33、25 2.086 1.645 1.960AValues in this table were calculated using Hewlett Packard HP 67/97 UsersLibrary Programs 03848D, “One-Sided and Two-Sided Critical Values of Studentst” and 00350D, “Improved Normal and Inverse Distribution.” For values at otherthan the 95 % probability level, see published tabl
34、es of critical values of Studentst in any standard statistical text (1), (2), (3), and (4).TABLE 2 Specimens Required Under Conditions of UnknownVariability in Users Laboratory, pH UnitsNames of the PropertiesNumber ofSpecimensBasisADistilled water at 21C 5 s = 0.154Distilled water at boil 7 s = 0.1
35、960.1 N NaCl solution at 21C 3 s = 0.1260.1 N NaCl solution at boil 3 s = 0.126AThe values of s in this table are somewhat larger than will usually be found inpractice (see 9.1.2).D 2165 94 (2006)210.3 Extraction with Boiling 0.1 N NaCl SolutionProceedas directed in 10.1 substituting 0.1 N NaCl solu
36、tion for thedistilled water. Measure the pH as directed in Section 11.10.4 Extraction with 0.1 N NaCl Solution at RoomTemperatureProceed as directed in 10.2, substituting 0.1 NNaCl solution for the distilled water. Measure the pH asdirected in Section 11.11. Procedure11.1 Immediately before use with
37、 the specimen, standardizethe pH meter and electrodes as directed in Section 8 of TestMethod E70, using standard buffers selected to bracket theexpected pH of the extract, at 21C.NOTE 2Caution: If calomel electrodes are used in the pH meter,adequate safety precautions need to be taken because calome
38、l (mercurouschloride) is a toxic substance.11.2 After the meter has been standardized as directed in11.1, wash the electrodes and sample container repeatedly withdistilled water until the indicated pH value no longer changes.This will require at least three changes of water. Remove thedrops of liqui
39、d hanging from the electrode by touching withabsorbent tissue.11.3 Remove the stopper from the flask for specimen No. 1and decant enough extract into the sample container to im-merse the electrodes 10 mm below the surface of the liquid.Restopper the flask. Agitate the solution with a stirring rod of
40、chemical-resistant glass or by rotating the sample containeruntil the pH reading reaches a steady value. Discard thisportion of the extract but do not rinse the electrodes. Disregardthe observed pH reading. In the same way, decant and measurethe pH value of further portions, without rinsing the elec
41、trodes,until two successive portions agree within 0.1 pH unit. Recordthese values and the average of the two values to the nearest0.01 unit.11.4 If the electrodes are mounted in a cell which does notpermit agitation, allow the first portion to stand for 3 min andsubsequent portions for 1 min before
42、taking a reading andproceed as directed in 11.3.11.5 Test each of the other specimens as directed in 11.3above, being certain not to rinse the electrodes between tests.12. Calculation12.1 Calculate the average pH of all pairs of the extracts ofeach specimen as the average of the last two readings an
43、dround the average to the nearest 0.1 pH unit.12.2 Using the results obtained for the first and secondspecimens, calculate the standard deviation of each specimencalculated to 0.01 pH unit and round to the nearest 0.1 pH unit.13. Report13.1 State that the tests were made on specimens preparedas dire
44、cted in Test Method D 2165, and that the pH wasmeasured as directed in Test Method E70. Describe thematerial or product sampled and the method of sampling used.13.2 Report the average pH value and standard deviationand state the extraction method. For example:AverageValueStan-dardDevia-tionpH at 21C
45、 distilled water = _ _ _ _ _ _ _ _pH at boil distilled water = _ _ _ _ _ _ _ _pH at 21C 0.1 N NaCl solution = _ _ _ _ _ _ _ _pH at boil 0.1 N NaCl solution = _ _ _ _ _ _ _ _14. Precision and Bias14.1 SummaryIn comparing two averages, the differencesshould not exceed the following critical difference
46、s in 95 casesout of 100 when all of the observations are taken by the samewell-trained operator using the same piece of test equipmentand specimens randomly drawn from the same sample ofmaterial:Distilled water at 21C 0.135 pH units for averages of 5Distilled water at boil 0.145 pH units for average
47、s of 70.1 N NaCl solution at 21C 0.143 pH units for averages of 30.1 N NaCl solution at boil 0.143 pH units for averages of 3The size of an observed difference is likely to be affectedadversely by different circumstances. The true values of theproperties tested by Test Method D 2165 can be defined o
48、nly interms of specific test methods. Within this limitation, theprocedures in Test Method D 2165 for determining theseproperties have no known bias. Paragraphs 14.2 and 14.3explain the basis for this summary and for evaluations madeunder other conditions.14.2 Interlaboratory Test Data4An interlabor
49、atory testwas run in 1967 in which randomly drawn samples of threematerials were tested in each of four laboratories. Eachlaboratory used one operator who tested two specimens of eachmaterial. The components of variance expressed as standarddeviations were calculated to be the values listed in Table 3.NOTE 3Since the interlaboratory tests included only four laboratories,between-laboratory precision data should be used with special caution.NOTE 4The tabulated values of the critical differences should becons
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