ASTM D1795-1996(2007)e1 Standard Test Method for Intrinsic Viscosity of Cellulose《纤维素固有粘度的标准试验方法》.pdf

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1、Designation: D 1795 96 (Reapproved 2007)e1Standard Test Method forIntrinsic Viscosity of Cellulose1This standard is issued under the fixed designation D 1795; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revisio

2、n. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.e1NOTESpecification E 1 was replaced with Specification E 2251 in Section 2 and 5.2 in June 2007.1. Scope1.1 This test method covers the dete

3、rmination of the intrin-sic viscosity of purified celluloses such as bleached woodpulps, cotton linters, and regenerated cellulose. It is applicableto all cellulose samples with an intrinsic viscosity of 15 dl/g orless. Most native (unpurified) celluloses have intrinsic viscos-ity values too high fo

4、r measurement by this test method.NOTE 1The use of cuprammonium hydroxide solution for regularviscosity determination is described in Method T 206 m-55 of theTechnical Association of Pulp and Paper Industry on “CuprammoniumDisperse Viscosity of Pulp,” and Joint Army-Navy Specifications JAN-C-206.1.2

5、 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.3 This standard does 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-

6、priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 445 Test Method for Kinematic Viscosity of Transparentand Opaque Liquids (and Calculation of Dynamic Viscos-ity)D 629 Test Methods for Quantitative

7、Analysis of TextilesE 2251 Specification for Liquid-in-Glass ASTM Thermom-eters with Low-Hazard Precision Liquids3. Summary of Test Method3.1 Aweighed sample of the material is dissolved in a 0.5 Mcupriethylenediamine hydroxide solution. The viscosity of thissolution, and also that of the solvent, i

8、s determined at 25C bymeans of a calibrated glass capillary-type viscometer. Therelative viscosity is calculated and the corresponding intrinsicviscosity is read from a table.4. Significance and Use4.1 This test is a sensitive measure of the degradation ofcellulose resulting from the action of heat,

9、 light, acids, alkalies,oxidizing and reducing agents, and the like, used in itsprocessing or purification. The intrinsic viscosity value may beconverted to degree of polymerization (DP) or to intrinsicfluidity, if desired.4.2 Solutions of cellulose are not Newtonian liquids; that is,their viscosity

10、 depends upon the rate-of-shear or velocitygradient during measurement.This effect is smaller for samplesof low molecular mass (DP) and at low concentrations than forhigh-DP samples and at high concentrations. For the cellulosesand concentrations included within the limits set forth in thistest meth

11、od, the effect of rate-of-shear is assumed to benegligible for referee purposes. For other conditions and forresearch purposes this assumption may be invalid, but todiscuss ways of accounting for this effect is beyond the scopeof the present test method.5. Apparatus5.1 Viscometer, Glass, Capillary T

12、ypeThe Cannon-Fenske, Ubbelohde, or similar capillary type instrument asdescribed in Test Method D 445 is recommended. In order toavoid correction for the kinetic energy effect, choose a viscom-eter with a small enough capillary to give an outflow time of 80s or more for the Cannon-Fenske type. (A s

13、ize 100 viscometeris normally used for the sample solution and a size 50 for thesolvent.)5.2 ThermometerASTM Kinematic Viscosity Thermom-eter for use at 25C, having a range from 19 to 27C andconforming to the requirement for Thermometer 17C asprescribed in Specification E 2251.5.3 BathA constant-tem

14、perature bath at 25C suitable forimmersion of the viscometer so that the reservoir or the top ofthe capillary, whichever is uppermost, is immersed at least 50mm, and with provision for visibility of the instrument and the1This test method is under the jurisdiction of ASTM Committee D01 on Paintand R

15、elated Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.36 on Cellulose and Cellulose Derivatives.Current edition approved June 1, 2007. Published July 2007. Originally approvedin 1960. Last previous edition approved in 2001 as D 1795 96 (2001)e1.2For referen

16、ced 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 onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West C

17、onshohocken, PA 19428-2959, United States.thermometer. Firm supports for the viscometer shall be pro-vided; or the viscometer may be sealed in as an integral part ofthe bath. Either a liquid bath with thermostatic regulation anda stirrer or a vapor bath with pressure regulation is permissible.The ef

18、ficiency of the stirring and the balance between heatlosses and heat input must be such that the temperature of thebath medium does not vary by more than 60.1C over thelength of the viscometer, or from viscometer to viscometer inthe various bath positions. If a vapor bath is used, there mustbe no te

19、mperature gradient over the length of the viscometergreater than that permitted in a liquid bath.5.4 TimerA stop watch or other spring-activated timingdevice or electrical timing device shall be used, graduated indivisions of 0.2 s or less, and accurate to within 0.05 % whentested over not less than

20、 a 10-min period. Such electricaltiming devices shall be used only on electrical circuits ofcontinuously controlled frequency. Frequency-controlled de-vices of suitable capacity for laboratory purposes, accurate towithin 1 part in 10 000 should be used. Errors exceeding0.05 % of a 10-min interval ma

21、y occur in timing devicesactuated by electrical synchronous motors driven by mostpublic power systems, which are intermittently and not con-tinuously controlled.6. Reagent6.1 Cupriethylenediamine Hydroxide Solution (1.00 6 0.01M), in copper, with the molar ratio of ethylenediamine tocopper of 2 6 0.

22、1 to 1. This solvent may be prepared in thelaboratory. It is also commercially available.37. Reference Materials7.1 Viscosity Oil StandardsCalibrating oils in the speci-fied ranges of viscosity.3Aqueous solutions of glycerol may beused instead of standardized oils; the compositions for variousviscos

23、ities are given in chemical handbooks. The applicableviscosity oil standards (Note 2) are listed in Table 1.NOTE 2The viscosity oil standards are available only as 4.7- m3(1-pt)samples. More than 1 pt of any given oil (for example, duplicate samples)are supplied only when it is established that 1 pt

24、 is inadequate.38. Calibration of Viscometer8.1 The following directions apply to the Cannon-Fenskeviscometer (Note 3). They should be modified according to theoperating instructions for other types of viscometers. Theviscometers shall be calibrated (Note 4) by means of liquidshaving known viscositi

25、es approximately equal to those of thesolvent and cellulose solutions respectively (1.2 and 12 cP,approximately).NOTE 3Detailed specifications and directions for filling, calibrating,and measurement with types of capillary viscometers most used are givenin Test Method D 445.NOTE 4Calibration of the

26、viscometers may be avoided if both solventand solution are measured in the same instrument. Then the relativeviscosity is nearly the ratio of outflow times for solution and solvent,respectively. This simplification involves two assumptions. The first, thatthe densities of solution and solvent are eq

27、ual, holds very well for thedilute solutions used in these tests. The second, that the kinetic energycorrection is zero, depends upon the choice of viscometer. If the one usedgives convenient outflow times for the solution of less than 150 s, then itwill be too fast for the solvent. The kinetic ener

28、gy correction is zero,depending upon flow. On the other hand, if one is chosen so that theoutflow time for the solvent is large enough (80 s or more), then the timesfor the solutions will in most cases be inconveniently long. For somework, however, it may be desirable to make some sacrifice in accur

29、acy orin convenience during measurement in order to avoid calibration andusing two sizes of viscometers.8.2 By means of a pipet, add 7.0 mLof the calibrating liquidto the viscometer, in a constant-temperature bath at 25 6 0.1C(or fill as described in Test Method D 445, Appendix A).8.3 When the liqui

30、d has reached temperature equilibriumwith the bath (in about 5 min), determine the outflow time t bydrawing the top meniscus of the liquid above the mark betweenthe two bulbs and measuring the time required for the meniscusto pass from this mark to the mark below the lower bulb. Takethe average of t

31、wo or more observations, which should differby not more than 0.2 s.8.4 Determine the viscometer constant C by the equation:C 5h/dt (1)where:h = viscosity of the calibrating liquid, cP,d = density, g/mL, andt = time, s.9. Preparation of Sample9.1 To avoid undesirable effects from long heating at high

32、temperature, samples should be air-dried and the moisturecontent determined on a portion that is not used for measure-ment of viscosity. The mass of air-dried samples is thencorrected for moisture to obtain the mass of oven-driedcellulose used to calculate concentration.9.2 Soft, sheeted pulp should

33、 be picked apart with tweezersor scraped with a dull knife. Hard-pressed or harsh pulp shouldbe slurried in water, formed into thin sheets on a Bchnerfunnel, and dried at a temperature below 100C (preferablyroom temperature). Loose pulp should be picked apart by handto break up any lumps. Slurried o

34、r slush pulps should beformed into thin sheets and dried. Yarn and staple should bewashed in warm water containing a little detergent to removethe finish, rinsed thoroughly, dried (at low temperature), andfluffed. (It will be found helpful to cut yarn and long staple intoshort lengths, say 13 mm (12

35、 in.), before washing.) Fabricsshould be cut into small pieces, desized (see Test MethodsD 629), thoroughly washed, and dried. Raveling will be helpful3The sole source of supply of the viscosity oil standards known to the committeeat this time is Cannon Instrument Co., P. O. Box 16, State College, P

36、A16801. If youare aware of alternative suppliers, please provide this information to ASTMInternational Headquarters. Your comments will receive careful consideration at ameeting of the responsible technical committee,1which you may attend.TABLE 1 Viscosity Oil StandardsViscometer Viscosity Oil Stand

37、ardSizeAbsolute ViscosityRange, cPADesignationApproximateAbsolute Viscosityat 25C (77F), cP501000.9to3.53.3 to 13.3S-3S-63.37.7AFor solution with density of 0.9.D 1795 96 (2007)e12before dissolving samples that tend to get in the solvent.Materials containing a considerable amount of non-cellulosicma

38、tter must first be purified; such treatments lie outside thescope of this test method.10. Preparation of Solution10.1 The sample size is dependent upon the nature of thematerial, smaller masses of high-viscosity celluloses and largermasses of low-viscosity celluloses being used in order to keepthe v

39、iscosity of the solutions within rather narrow limits.(Working at nearly constant viscosity reduces the effect of rateof shear upon the measurements.) The concentration for eachsample is chosen according to the rule:hc 5 3.09 6 0.5 (2)where:h = intrinsic viscosity, dL/g, andc = cellulose concentrati

40、on, g/dL.Obviously, use of this rule requires knowledge of theapproximate intrinsic viscosity of the sample before the con-centration can be estimated. In routine control work, suchinformation is available. If it is not, Table 2 will serve as anapproximate guide.10.2 Make up a preliminary solution o

41、f about the indicatedconcentration, and determine the viscosity as described inSections 11 and 12. From the relative viscosity thus obtained,find the approximate value of the intrinsic viscosity by meansof Table 3. From this determine the concentration needed togive: h c = 3.0. If this preliminary s

42、olution does not give avalue of hc of 3.0 6 0.5, prepare a second solution of theindicated concentration for the final viscosity measurement.10.3 Alkaline solutions of cellulose are known to be sensi-tive to oxidation. Hence it is usually necessary to exclude airduring solution of the sample; severa

43、l ways of doing this aredescribed in the literature, but the following is simple andadequate: Weigh out the calculated amount of air-dried cellu-lose (corrected to oven-dry mass) and transfer quantitatively toa suitable glass or polyethylene container (capacity somewhatmore than 50 mL) that can be t

44、ightly closed by a stopper orscrew cap.Add 25.0 mLof distilled water from a pipet or buret,insert the stopper or cap, and shake in order to wet out anddisperse the sample. Sweep the air from the vessel with astream of nitrogen and, with the nitrogen still flowing, add 25.0mL of solvent. Stopper or c

45、ap tightly and shake vigorously byhand or in a mechanical shaker until the cellulose is completelydissolved.NOTE 5Most work pulp and regenerated celluloses dissolve within 5min. Mercerized celluloses do not dissolve as easily in cupriethylenedi-amine as in cuprammonium solvent and require longer tim

46、es (up to 1 h).Some operators report difficulty in dissolving native celluloses includingcotton linters with degree of polymerization (DP) as low as that of woodpulps. The difficulty shows up by much poorer precision of results than the1 to 2 % that is normally obtained between measurements made wit

47、h twoor more solutions of the same sample. Even solutions that leave no residueon fritted-glass filters have been observed to give erratic results. Inad-equate dispersion of the sample is apparently the cause, and twomodifications in procedure have been recommended in such cases. One isto add about

48、0.04 % wetting agent to the water used to wet out thesample.4The other requires use of cupriethylenediamine solutions of twoconcentrations: The sample is wetted out with one solution that is 0.167 Min copper and dispersion is completed by adding the second solution,1.000 M in copper, in such volume

49、as to make the final copperconcentration 0.500 M.11. Measurement of Viscosity11.1 Transfer 7.0 mL of the solution by means of a syringeor pipet to a viscometer previously placed in the bath at 25Cand flushed with nitrogen (or fill as described in Test MethodD 445, Appendix A). Allow at least 5 min for the solution toreach bath temperature.11.2 By applying either pressure (with nitrogen) or suction,draw the solution into the lower bulb of the viscometer until thetop meniscus is a little above the mark between the two bulbs.Measure the time t required for