1、Designation: D2165 94 (Reapproved 2012)1Standard Test Method forpH of Aqueous Extracts of Wool and Similar Animal Fibers1This standard is issued under the fixed designation D2165; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the
2、 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.1NOTEThe terminology section was updated
3、 in July 2012.1. Scope1.1 This test method covers the 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,
4、 if 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. For specificprecautionary statements, see Section 11.2. Referenced Documents2.1 ASTM S
5、tandards:2D123 Terminology Relating to TextilesD2525 Practice for Sampling Wool for MoistureD4845 Terminology Relating to WoolE70 Test Method for pH of Aqueous Solutions With theGlass Electrode3. Terminology3.1 For all terminology related to D13.13, refer to Termi-nology D4845.3.1.1 The following te
6、rms are relevant to this standard:aqueous extract, pH.3.2 For all other terminology related to textiles, see Termi-nology D123.4. 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. Th
7、e pH of the extract is measuredelectrometrically with a glass electrode.5. Significance and Use5.1 The pH values 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
8、 subsequent performance. For particularpurposes, the pH of an extract prepared by one method may bea more informative 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 p
9、recision is relativelypoor. In some cases, the purchaser and the seller may have totest a commercial shipment 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 disag
10、reement arising fromdifferences in values reported by the purchaser and the sellerwhen using this method for 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 speci
11、mens randomly drawnfrom one sample of material of the type being evaluated.6. Apparatus and Materials6.1 All 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 thor
12、oughly with distilled water (see 7.1) until therinsings have a pH of 6.0 or higher.NOTE 1It is desirable but not mandatory that the glassware bereserved for extraction tests only and be filled with distilled water duringstorage between tests.6.2 Apparatus for Extraction at Room Temperature:6.2.1 Erl
13、enmeyer 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.1This test method is under the jurisdiction of ASTM Co
14、mmittee D13 on Textilesand is the direct responsibility of Subcommittee D13.13 on Wool and Felt.Current edition approved July 1, 2012. Published August 2012. Originallyapproved in 1961. Last previous edition approved in 2006 as D2165 94(2006).DOI: 10.1520/D2165-94R12E01.2For referenced ASTM standard
15、s, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Borosilicate glass has been found satisfactory.1Copyright ASTM International, 100 Barr Ha
16、rbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.3 Additional Equipment Needed for Extraction at TheBoil:6.3.1 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
17、.4 Glass Stopper, for flask, equipped with a stopcock andthermometer with a range from 0 to 105C.6.4 pH Meter and Glass Electrode, conforming 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, redis
18、tillation is necessary.7.2 Sodium Chloride, Standard Solution (0.1 N), preparedfrom reagent grade sodium chloride (NaCl) and distilled 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
19、a lot sample of raw wool, scoured wool, sliver, top,yarn, or fabrics as specified in the sampling procedure inPractice D2525.8.2 Select 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 Specimen
20、s9.1 Take a number of specimens per laboratory samplingunit such that the user can expect at the 95 % probability levelthat the test 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 Reliab
21、le Estimate of sWhen there is a reliableestimate of s based upon extensive past records in the userslaboratory as directed in the test 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(rou
22、nded upward to a whole number),s = reliable estimate of the standard deviation of individualobservations on similar materials in the 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 assoc
23、i-ated with the estimate of v (Table 1), andE = 0.5 percentage points, the allowable variation.9.1.2 No Reliable Estimate of sWhen there 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 numbe
24、rs of specimens are calculatedusing values of s which are listed in Table 2 and which aresomewhat larger values of s than are usually 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. Pre
25、paration of Extracts10.1 Extraction with Boiling Water Include an approxi-mately proportionate quantity of any fallout present in eachspecimen. Transfer each specimen to a separate flask. Coverthe fibers with 200 mL of boiling water (see 7.1). Connect thereflux condenser, making certain that anhydro
26、us calcium sul-fate absorbent is in the absorption tube. Shake, to completewetting of the fiber, and heat gently to maintain boiling.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
27、 as quickly as possiblewith a stopper containing a thermometer. Cool the flask andcontents in water maintained at 21 6 2C, without removingthe 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 Temperatu
28、reTake thetwo specimens, including an approximately proportionatequantity of any fallout present. Transfer each specimen to aseparate 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 h
29、and forTABLE 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 2.160 26 1.706 2.0564 2.132 2.776 1
30、4 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 1.725 2.086 1.645 1.960AValues in this
31、 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 tables of critical values of Studentst
32、in any standard statistical text (1), (2), (3), and (4).D2165 94 (2012)12about 30 s to wet the specimen thoroughly and then agitatemechanically for2hatarate that will not warm the solutionabove 28C. Measure the pH as directed in Section 11.10.3 Extraction with Boiling 0.1 N NaCl SolutionProceedas di
33、rected in 10.1 substituting 0.1 N NaCl solution 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
34、. Procedure11.1 Immediately before use with 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
35、precautions need to be taken because calomel (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
36、 changes of water. Remove thedrops of liquid 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.
37、Agitate the solution with a stirring rod ofchemical-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
38、 further portions, without rinsing the electrodes,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 m
39、in andsubsequent portions for 1 min before 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
40、 as the average of the last two readings andround 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 t
41、ests were made on specimens preparedas directed in Test Method D2165, 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 exampl
42、e: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 = 0.1960.1 N NaCl solution at 21C 3 s = 0.1260.1 N NaCl solution at boil 3 s = 0.126AThe value
43、s of s in this table are somewhat larger than will usually be found inpractice (see 9.1.2).D2165 94 (2012)13AverageValueStan-dardDevia-tionpH at 21C distilled water = _ _ _ _ _ _ _ _pH at boil distilled water = _ _ _ _ _ _ _ _pH at 21C 0.1 N NaCl solution = _ _ _ _ _ _ _ _pH at boil 0.1 N NaCl solut
44、ion = _ _ _ _ _ _ _ _14. Precision and Bias14.1 SummaryIn comparing two averages, the differencesshould not exceed the following critical differences 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 rand
45、omly 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 averages 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 dif
46、ference is likely to be affectedadversely by different circumstances. The true values of theproperties tested by Test Method D2165 can be defined only interms of specific test methods. Within this limitation, theprocedures in Test Method D2165 for determining theseproperties have no known bias. Para
47、graphs 14.2 and 14.3explain the basis for this summary and for evaluations madeunder other conditions.14.2 Interlaboratory Test Data4An interlaboratory testwas run in 1967 in which randomly drawn samples of threematerials were tested in each of four laboratories. Eachlaboratory used one operator who
48、 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 t
49、abulated values of the critical differences should beconsidered to be a general statement, particularly with respect to between-laboratory precision. Before a meaningful statement can be made abouttwo specified laboratories, the amount of statistical bias, if any, betweenthem must be established, with each comparison being based on recentdata obtained on randomized specimens from one sample of the materialto be tested.14.3 BiasThe true values of the properties listed in Table3 and Table 4 can only be
