ASTM D871-1996(2004) Standard Test Methods of Testing Cellulose Acetate《测试乙酸纤维素的试验方法》.pdf

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1、Designation: D 871 96 (Reapproved 2004)Standard Test Methods of TestingCellulose Acetate1This standard is issued under the fixed designation D 871; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number

2、 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 cover procedures for testing cellu-lose

3、acetate.1.2 The test procedures appear in the following sections:SectionsAsh 8 to 11Color and Haze 67 to 72Combined Acetyl or Acetic Acid ContentTest Method A. Solution Method 17, 19 to 23Test Method B. Heterogeneous Saponification Method 17, 24 to 26Free Acidity 12 to 16Heat Stability 47 to 56Hydro

4、xyl Content 27 to 33Intrinsic Viscosity 57 to 62Moisture Content 4 to 7Primary Hydroxyl Content 34 to 39Sulfur or Sulfate Content 40 to 45Viscosity 63 to 661.3 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.4 This standard d

5、oes not purport to address all of thesafety concerns, 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.2. Referenced Documents2.1 ASTM St

6、andards:2D 1193 Specification for Reagent WaterD 1343 Test Method for Viscosity of Cellulose Derivativesby Ball-Drop MethodD 2929 Test Method for Sulfur Content of Cellulosic Ma-terials by X-Ray FluorescenceD 5897 Test Method for Determination of Percent Hydroxylon Cellulose Esters by Potentiometric

7、 TitrationAlternative Method3. Purity of Reagents3.1 Reagent grade chemicals shall be used in all tests.Unless otherwise indicated, it is intended that all reagents shallconform to the specifications of the Committee on AnalyticalReagents of the American Chemical Society, where suchspecifications ar

8、e available.3Other grades may be used, pro-vided it is first ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.3.2 Unless otherwise indicated, references to water shall beunderstood to mean reagent tared, low, wide-form we

9、ighingbottle and water, conforming to Specification D 1193.MOISTURE CONTENT4. Significance and Use4.1 Moisture content of the cellulose ester can be used toestimate the dry weight of the cellulose ester. Since celluloseesters are desiccants, their moisture content can vary greatlydepending on storag

10、e.5. Procedure5.1 Transfer about5gofthesample to a tared, low,wide-form weighing bottle and weigh to the nearest 0.001 g.Dry in an oven for2hat1056 3C. Remove the bottle fromthe oven, cover, cool in a desiccator, and weigh.6. Calculation6.1 Calculate the percentage of moisture as follows:Moisture, %

11、 5 A/B! 3 100where:1These test methods are under the jurisdiction of ASTM Committee D01 onPaint and Related Coatings, Materials, and Applications and are the directresponsibility of Subcommittee D01.36 on Cellulose and Cellulose Derivatives.Current edition approved June 1, 2004. Published June 2004.

12、 Originallyapproved in 1946. Last previous edition approved in 1996 as D 871 96.2For referenced ASTM standards, 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

13、onthe ASTM website.3Reagent 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, Dorset, U.K., and the Unite

14、d States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.A = weight loss on heating, g, andB = sample used, g.7. Precision and Bias7.1 No st

15、atement on bias can be made as no referencematerial is available as a standard.ASH8. Significance and Use8.1 Ash content gives an estimate of the inorganic contentof cellulose ester samples. The presence of high levels ofinorganic content (ash) can be detrimental to the melt stabilityand optical cla

16、rity of a cellulose ester in melt processing or actas a potential source of insolubles when the ester is used insolution.9. Procedure9.1 Dry the sample for2hat1056 3C and weigh 10 to 50g, to the nearest 0.01 to 0.1 g, depending on its ash content andthe accuracy desired. An air-dried sample may be u

17、sed andcalculated to dry weight using the value for moisture deter-mined as in Sections 5 and 6. Burn directly over a flame in a100-mL tared platinum crucible that has been heated toconstant weight and weighed to the nearest 0.1 mg. Add thesample in portions if more than 10 g is taken. The samplesho

18、uld burn gently and the portions should be added as theflame subsides. Continue heating with a burner only as long asthe residue burns with a flame. Transfer the crucible to a mufflefurnace and heat at 550 to 600C for 3 h, or longer if required,to burn all the carbon. Allow the crucible to cool and

19、thentransfer it, while still warm, to a desiccator. When the cruciblehas cooled to room temperature, weigh accurately to thenearest 0.1 mg.10. Calculation10.1 Calculate the percentage of ash as follows:Ash, % 5 A/B! 3 100where:A = ash, g, andB = sample used, g.11. Precision and Bias11.1 No statement

20、 on bias can be made as no referencematerial is available as a standard.FREE ACIDITY12. Significance and Use12.1 Free Acidity is a measure of unesterified organic acidin the ester. The presence of high levels of free acid ispotentially detrimental to the melt processing of the ester andcan impact th

21、e odor of the ester.13. Reagents13.1 Phenolphthalein Indicator Solution (1 g/100 mL)Dissolve1gofphenolphthalein in 100 mL of ethyl alcohol(95 %).13.2 Sodium Hydroxide, Standard Solution (0.01 N)Prepare and standardize a 0.01 N solution of sodium hydroxide(NaOH).14. Procedure14.1 Shake5gofthesample,

22、ground to pass a No. 20 (850m) sieve and corrected for moisture content if necessary, in a250-mL Erlenmeyer flask with 150 mL of freshly boiled, coldwater. Stopper the flask and allow it to stand for 3 h. Filter offthe cellulose acetate and wash it with water. Titrate thecombined filtrate and washin

23、gs with 0.01 N NaOH solution,using phenolphthalein indicator solution.14.2 Run a blank determination on the water, using the samevolume as was used in extracting the sample.15. Calculation15.1 Calculate the percentage of acidity as free acetic acidas follows:Free acetic acid, % 5 A 2 B!N 3 0.06 3 10

24、0/W (1)where:A = NaOH solution used to titrate the sample, mL,B = NaOH solution used to titrate the blank, mL,N = normality of the NaOH solution, andW = sample used, g.16. Precision and Bias16.1 No statement on bias can be made as no referencematerial is available as a standard.COMBINED ACETYL OR AC

25、ETIC ACID CONTENT17. Scope17.1 Two test methods are described for determining thecombined acetyl or acetic acid content. The first, described inSections 19 to 22, is more precise, but less widely applicable,than the method described in Sections 24 to 26.18. Significance and Use18.1 Acetyl or acetic

26、acid content is a measure of theamount of acetic acid esterified onto the cellulose backbone ofthe polymer. The amount of substitution of acetate ester has avery strong effect on the polymers solubility and physicalproperties.Test Method ASolution Method19. Apparatus19.1 Weighing Bottle, glass-stopp

27、ered, 15-mL capacity,25-mm diameter by 50-mm high.19.2 Tray, copper or aluminum, approximately 136.5 mm (538 in.) square, containing 25 compartments 25.4 mm (1 in. )square. Each compartment shall have the correct dimensions tocontain one weighing bottle. The entire tray shall fit inside adesiccator

28、and should have a basket-type handle to facilitatethe introduction and removal of the tray (convenient but notessential).19.3 Buret, automatic zero, 35-mL, 25-mL bulb, stemgraduated from 25 to 35 mL in 0.05-ml increments; or pipet,automatic zero, 30-mL, for 1.0 N NaOH solution.D 871 96 (2004)219.4 B

29、uret, automatic zero, 15-mL, 10-mL bulb, stemgraduated from 10 to 15 mL in 0.05-mL increments, for 1 NH2SO4.19.5 Buret, 5-ml, in 0.01 or 0.1-mL divisions, for backtitration with 0.1 N NaOH solution.19.6 Magnetic Stirrer, for single flask.19.7 Magnetic Stirrer, capacity twelve or more flasks.19.8 Sti

30、rring Bars, stainless steel Type 416, length 50 mm,diameter 5 to 6 mm, or equivalent, dimensions not critical.20. Reagents20.1 AcetoneAdd one 30-mL portion of 1.0 N NaOHsolution to a mixture of 150 mL acetone and 100 mL hot water,allow to stand with frequent swirling for 30 min, and titratewith 1.0

31、N H2SO4. Add another 30-mL portion of 1.0 N NaOHsolution to 100 mL of hot water, allow to stand for 30 min, andtitrate. The difference between the two titrations shall notexceed 0.05 mL.20.2 Dimethyl Sulfoxide.20.3 Pyridine.20.4 Sodium Hydroxide Solution (40 g/L)Dissolve 40 g ofsodium hydroxide (NaO

32、H) in water and dilute to 1 L.20.5 Sodium Hydroxide, Standard Solution (0.1 N)Prepare and standardize a 0.1 N solution of NaOH.20.6 Sulfuric Acid (1.0 N)Prepare and standardize a 1.0N solution of sulfuric acid (H2SO4).20.7 Phenolphthalein Indicator Solution (1 g/100 mL)Dissolve1gofphenolphthalein in

33、 100 ml of ethyl alcohol(95 %).21. Procedure21.1 Dry 1.9 6 0.05 g of the ground well-mixed sample ina weighing bottle for2hat1056 3C and weigh the driedsample by difference to the nearest 1 mg into a 500-mLwide-mouth Erlenmeyer flask. Prepare a blank by dryingapproximately 3.8 g of potassium acid ph

34、thalate and weighingit by difference into a flask as described. Carry the blankthrough the entire procedure.NOTE 1Potassium acid phthalate is used so that the concentration ofthe NaOH in contact with the solvent in the blank will be approximatelythe same as that in contact with the sample and so tha

35、t the titration of theblank will be approximately the same as the titration of the sample, thusavoiding errors caused by using a different buret for the titration of theblank and the sample or by refilling the 15-mL buret. If desired, however,the potassium acid phthalate may be omitted.21.2 If the a

36、cetyl content is 32 to 41 % or the acetic acidcontent is 45 to 57 %, put the sample into solution as follows:Add 150 mL of acetone and 5 to 10 mL of water and swirl tomix. Stopper the flask and allow it to stand with occasionalswirling until solution is complete. Solution may be hastenedby magnetic

37、stirring or by any suitable mechanical shaking thatwill provide a gentle rocking type of agitation to avoidsplashing the solution on the stopper. It is essential thatcomplete solution be effected. Proceed in accordance with21.4.21.3 If the acetyl content is 41 to 44.8 % or the acetic acidcontent is

38、57 to 62.5 %, dissolve the sample by either of thefollowing two methods:21.3.1 Gently rotate the flask by hand to distribute andspread the sample in a thin layer over the bottom of the flask.Add 70 mL of acetone to the flask and swirl gently until thesample particles are completely wetted and evenly

39、 dispersed.Stopper the flask and allow it to stand undisturbed for 10 min.Carefully add 30 mL of dimethyl sulfoxide from a graduate tothe flask, pouring the solvent down the sides of the flask towash down any sample particles clinging to the side. Stopperthe flask and allow it to stand with occasion

40、al swirling untilsolution is complete. Magnetic stirring or gentle mechanicalagitation that will not splash the solution is recommended.When solution appears to be complete, add 50 mL of acetoneand swirl or stir for 5 min. Proceed in accordance with 21.4.21.3.2 Dimethyl sulfoxide is the preferred so

41、lvent, but if itis not available, spread the sample in a thin layer over thebottom of the flask, add 15 mL of acetone, swirl to wet theparticles with acetone, stopper the flask, and allow the mixtureto stand undisturbed for 20 min. Add 75 mL of pyridinewithout shaking or swirling, and allow to stand

42、 for 10 min.Heat the solution just to boiling and swirl or stir for 5 min.Again heat to boiling and swirl or stir for 10 min. Continue toheat and stir until the mixture is homogeneous and all large gelmasses are broken down into individual highly swollen par-ticles. When these highly swollen gel par

43、ticles are welldispersed and are not fused together in large gel masses, nofurther heating is necessary. Cool the flask, add 30 mL ofacetone, and swirl or stir for 5 min. Proceed in accordance with21.4.21.4 Add 30 mL of NaOH solution (40 g/L) with constantswirling or stirring to the solution of the

44、sample and also to theblank. Use of a magnetic stirrer is recommended (Note 2). It isabsolutely necessary that a finely divided precipitate of regen-erated cellulose, free from lumps, be obtained. Stopper theflask and let the mixture stand with occasional swirling, or stiron the magnetic stirring un

45、it. Allow 30 min for saponificationof lower acetyl samples, 2 h for high acetyl samples whendimethyl sulfoxide is the solvent, and 3 h when pyridine is thesolvent. At the end of the saponification period, add 100 mL ofhot water, washing down the sides of the flask, and stir for 1 or2 min. Add 4 or 5

46、 drops of phenolphthalein indicator solutionand titrate the excess NaOH solution with 1.0 N H2SO4(Note3). Titrate rapidly with constant swirling or stirring ring untilthe end point is reached; then add an excess of 0.2 or 0.3 mLof H2SO4. Allow the mixture to stand with occasional stirringor preferab

47、ly stir on the magnetic stirrer for at least 10 min.Then add 3 drops of phenolphthalein indicator solution to eachflask and titrate the small excess of acid with 0.1 N NaOHsolution to a persistent phenolphthalein end point. Take ex-treme care to locate this end point; after the sample is titratedto

48、a faint pink end point, swirl the mixture vigorously or placeit for a moment on the magnetic stirrer. If the end point fadesbecause of acid soaking from the cellulose, continue theaddition of 0.1 N NaOH solution until a faint persistent endpoint remains after vigorous swirling or stirring. Titrate t

49、heblank in the same manner as the sample.NOTE 2While the amount of magnetic stirring is somewhat optional,such stirring during the entire period of the determination is stronglyD 871 96 (2004)3recommended. Solution is more rapid, titrations are more rapid, and theend point can be approached directly and without a back titration.NOTE 3It is important to correct all 1.0 N H2SO4buret readings fortemperature and buret corrections.22. Calculation22.1 Calculate the percentage by weight of acetyl and aceticacid as follows:Acetyl or acetic acid, % (2)5 D 2 C!Na1