1、Designation: D1795 13Standard Test Method forIntrinsic Viscosity of Cellulose1This standard is issued under the fixed designation D1795; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parenth
2、eses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of the intrin-sic viscosity of purified celluloses such as bleached woodpulps, cotton linters, and regenerated
3、 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 for measurement by this test method.NOTE 1The use of cuprammonium hydroxide solution for regularviscosity determination is
4、 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 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard
5、.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-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced
6、Documents2.1 ASTM Standards:2D445 Test Method for Kinematic Viscosity of Transparentand Opaque Liquids (and Calculation of Dynamic Viscos-ity)D629 Test Methods for Quantitative Analysis of TextilesE1 Specification for ASTM Liquid-in-Glass ThermometersE2251 Specification for Liquid-in-Glass ASTM Ther
7、mom-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, is determined at 25C bymeans of a calibrated glass capillary-type visco
8、meter. 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, light, acids, alkalies,oxidizing and reducing agents, and the like, u
9、sed 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 depends upon the rate-of-shear or velocitygradient during measurement
10、.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 method, the effect of rate-of-shear is assumed to benegligible for referee
11、 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 TypeThe Cannon-Fenske, Ubbelohde, or similar capillary type instrument
12、asdescribed in Test Method D445 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 size 100 viscometeris normally used for the sample solution and a size 5
13、0 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 E1. Thermometric devices such asRTDs, thermistors and liquid-in-glass thermometers (as speci-fied in
14、 Specification E2251) of equal or better accuracy in thespecified temperature range, may be used.5.3 BathA constant-temperature bath at 25C suitable forimmersion of the viscometer so that the reservoir or the top ofthe capillary, whichever is uppermost, is immersed at least 501This test method is un
15、der the jurisdiction of ASTM Committee D01 on Paintand Related Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.36 on Cellulose and Cellulose Derivatives.Current edition approved June 1, 2013. Published July 2013. Originally approvedin 1960. Last previous edi
16、tion approved in 2007 as D1795 96 (2007)1. DOI:10.1520/D1795-13.2For 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 onthe ASTM websi
17、te.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1mm, and with provision for visibility of the instrument and thethermometer. Firm supports for the viscometer shall be pro-vided; or the viscometer may be sealed in as an integral part
18、 ofthe bath. Either a liquid bath with thermostatic regulation anda stirrer or a vapor bath with pressure regulation is permissible.The efficiency 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 ov
19、er thelength of the viscometer, or from viscometer to viscometer inthe various bath positions. If a vapor bath is used, there mustbe no temperature 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 e
20、lectrical timing device shall be used, graduated indivisions of 0.2 s or less, and accurate to within 0.05 % whentested over not less than a 10-min period. Such electricaltiming devices shall be used only on electrical circuits ofcontinuously controlled frequency. Frequency-controlled de-vices of su
21、itable capacity for laboratory purposes, accurate towithin 1 part in 10 000 should be used. Errors exceeding0.05 % of a 10-min interval may occur in timing devicesactuated by electrical synchronous motors driven by mostpublic power systems, which are intermittently and not con-tinuously controlled.6
22、. Reagent6.1 Cupriethylenediamine Hydroxide Solution (1.00 6 0.01M), in copper, with the molar ratio of ethylenediamine tocopper of 2 6 0.1 to 1. This solvent may be prepared in thelaboratory. It is also commercially available.37. Reference Materials7.1 Viscosity Oil StandardsCalibrating oils in the
23、 speci-fied ranges of viscosity.3Aqueous solutions of glycerol may beused instead of standardized oils; the compositions for variousviscosities are given in chemical handbooks. The applicableviscosity oil standards (Note 2) are listed in Table 1.NOTE 2The viscosity oil standards are available only a
24、s 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 is inadequate.38. Calibration of Viscometer8.1 The following directions apply to the Cannon-Fenskeviscometer (Note 3). They should be modified according to theop
25、erating instructions for other types of viscometers. Theviscometers shall be calibrated (Note 4) by means of liquidshaving known viscosities approximately equal to those of thesolvent and cellulose solutions respectively (1.2 and 12 cP,approximately).NOTE 3Detailed specifications and directions for
26、filling, calibrating,and measurement with types of capillary viscometers most used are givenin Test Method D445.NOTE 4Calibration of the 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 sol
27、ution and solvent,respectively. This simplification involves two assumptions. The first, thatthe densities of solution and solvent are equal, 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
28、the one usedgives convenient outflow times for the solution of less than 150 s, then itwill be too fast for the solvent. The kinetic energy 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 tim
29、esfor the solutions will in most cases be inconveniently long. For somework, however, it may be desirable to make some sacrifice in accuracy 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 liqui
30、dto the viscometer, in a constant-temperature bath at 25 6 0.1C(or fill as described in Test Method D445, Appendix A).8.3 When the liquid 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
31、 two bulbs and measuring the time required for the meniscusto pass from this mark to the mark below the lower bulb. Takethe average of two or more observations, which should differby not more than 0.2 s.8.4 Determine the viscometer constant C by the equation:C 5 /dt (1)where: = viscosity of the cali
32、brating liquid, cP,d = density, g/mL, andt = time, s.9. Preparation of Sample9.1 To avoid undesirable effects from long heating at hightemperature, 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 sample
33、s is thencorrected for moisture to obtain the mass of oven-driedcellulose used to calculate concentration.9.2 Soft, sheeted pulp should 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 dri
34、ed at a temperature below 100C (preferablyroom temperature). Loose pulp should be picked apart by handto break up any lumps. Slurried or slush pulps should beformed into thin sheets and dried. Yarn and staple should bewashed in warm water containing a little detergent to remove3The sole source of su
35、pply of the viscosity oil standards known to the committeeat this time is Cannon Instrument Co., P. O. Box 16, State College, PA16801. If youare aware of alternative suppliers, please provide this information to ASTMInternational Headquarters. Your comments will receive careful consideration at amee
36、ting of the responsible technical committee,1which you may attend.TABLE 1 Viscosity Oil StandardsViscometer Viscosity Oil StandardSizeAbsolute ViscosityRange, cPADesignationApproximateAbsolute Viscosityat 25C, cP501000.9to3.53.3 to 13.3S-3S-63.37.7AFor solution with density of 0.9.D1795 132the finis
37、h, rinsed thoroughly, dried (at low temperature), andfluffed. (It will be found helpful to cut yarn and long staple intoshort lengths, say 13 mm (12 in.), before washing.) Fabricsshould be cut into small pieces, desized (see Test MethodsD629), thoroughly washed, and dried. Raveling will be helpfulbe
38、fore dissolving samples that tend to get in the solvent.Materials containing a considerable amount of non-cellulosicmatter 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, sma
39、ller masses of high-viscosity celluloses and largermasses of low-viscosity celluloses being used in order to keepthe viscosity of the solutions within rather narrow limits.(Working at nearly constant viscosity reduces the effect of rateof shear upon the measurements.) The concentration for eachsampl
40、e is chosen according to the rule:#c 5 3.0960.5 (2)where: = intrinsic viscosity, dL/g, andc = cellulose concentration, 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, suchinfo
41、rmation is available. If it is not, Table 2 will serve as anapproximate guide.10.2 Make up a preliminary solution of 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
42、viscosity by meansof Table 3. From this determine the concentration needed togive: c = 3.0. If this preliminary solution does not give avalue of c 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
43、to be sensi-tive to oxidation. Hence it is usually necessary to exclude airduring solution of the sample; several 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 trans
44、fer quantitatively toa suitable glass or polyethylene container (capacity somewhatmore than 50 mL) that can be tightly 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 fr
45、om the vessel with astream of nitrogen and, with the nitrogen still flowing, add 25.0mL of solvent. Stopper or cap 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
46、 celluloses do not dissolve as easily in cupriethylenedi-amine as in cuprammonium solvent and require longer times (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
47、 up by much poorer precision of results than the1 to 2 % that is normally obtained between measurements made with 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
48、apparently the cause, and twomodifications in procedure have been recommended in such cases. One isto add about 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
49、is 0.167 Min copper and dispersion is completed by adding the second solution,1.000 M in copper, in such volume 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 MethodD445, 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 t
