ASTM D6188-17 Standard Test Method for Viscosity of Cellulose by Cuprammonium Ball Fall.pdf

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1、Designation: D6188 17Standard Test Method forViscosity of Cellulose by Cuprammonium Ball Fall1This standard is issued under the fixed designation D6188; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A n

2、umber in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method describes the procedure for estimatingthe molecular weight of cellulose by determining the viscosityof cuprammonium (Cu

3、Am) solutions of cellulosic materials,such as wood pulp, cotton, and cotton linters. This test methodis suitable for rapid, routine testing of large numbers ofsamples with high accuracy and precision. This test methodupdates and extends the procedure reported by the AmericanChemical Society (ACS).21

4、.2 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 appr

5、o-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of Int

6、ernational Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:3D1193 Specification for Reagent WaterD1695 Terminology of Cellulose and Cellulose DerivativesE438 Specification for Glasses i

7、n Laboratory Apparatus3. Terminology3.1 This standard terminology of cellulose and cellulosederivatives, see Terminology D1695.4. Summary of Test Method4.1 An in-process or finished product sample is taken. Allcooking and bleaching chemicals must be washed out ofin-process samples. Dry samples are w

8、etted with demineral-ized water. Samples are either squeezed or pressed to 20 to40 % consistency as necessary, then passed through a picker.4.2 The wet pulp sample is dried with air whose maximumtemperature is 120C and weighed under conditions that causethe specified quantity of sample to be obtaine

9、d. The weighedsample is placed in a glass 120-mL (4-oz) bottle, steel shot areadded, a vacuum is pulled on the bottle, and 97 mL ofcuprammonium solution are added to the bottle. The bottle isplaced on a shaker to mix and dissolve the pulp sample in theCuAm solution.4.3 The dissolved sample is transf

10、erred to a glass viscositytube. The tube is mounted vertically with a bright light behindthe tube. A special glass bead (see 7.13) is dropped into thecenter of the solution in the tube. The time is measured inseconds (s) for the glass bead to pass between two marks on thetube which are 20 cm apart.

11、This time (s) is the uncorrected “asis” cuprammonium ball fall viscosity. The temperature of thesolution is determined, and the correction factor for thistemperature is multiplied by the uncorrected viscosity of thesample. This gives the “as is” cuprammonium ball fall viscos-ity value.4.4 The “as is

12、” viscosity value for the sample size used isconverted to the 2.50-g ACS viscosity by the equationsprovided in 14.4. The viscosity is reported in “ACS seconds.”5. Significance and Use5.1 This test method is suitable for use as a rapid control testfor pulp manufacture or for careful determination of

13、theviscometric molecular weight of purified cotton or woodderived pulps.5.2 This test method is applicable over a very large range ofcellulose molecular weights because seven sample sizes aredefined. (Sample weights are reduced as cellulose molecularweight increases.)1This test method is under the j

14、urisdiction of ASTM Committee D01 on Paintand Related Coatings, Materials, andApplications and is the direct responsibility ofSubcommittee D01.36 on Cellulose and Cellulose Derivatives.Current edition approved June 1, 2017. Published June 2017. Originallyapproved in 1997. Last previous edition appro

15、ved in 2008 as D6188 97 (2008)which was withdrawn January 2017 and reinstated in June 2017. DOI: 10.1520/D6188-17.2Carver et al., “A Standard Method for Determining the Viscosity of Cellulosein Cuprammonium Hydroxide,” Industrial and Engineering Chemistry, AnalyticalEdition, Vol 1, No 1, 1929, pp. 4

16、9-51.3For 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 website.Copyright ASTM International, 100 Barr Harbor Drive, PO

17、Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by

18、 the World Trade Organization Technical Barriers to Trade (TBT) Committee.15.3 Cotton and high molecular weight pulps may be difficultto dissolve. (WarningThis test method is only valid if thesample dissolves completely without gels.)6. Interferences6.1 High temperature drying of pulp causes a reduc

19、tion inviscosity. Therefore, limit the maximum temperature of the airused to dry the sample to 120C and the maximum drying timeto 20 min to keep viscosity loss to a minimum. All in-processsamples must be washed to remove cooking and bleachingchemicals, because the presence of chemicals while drying

20、willincrease viscosity loss.6.2 The weight of sample used with this test method iscritical. The effect of incorrect sample weight on viscosity isshown in Table 1.6.2.1 If the pulp sample is properly weighed but a smallamount fails to dissolve, the viscosity will be incorrect by atleast the percentag

21、e of the sample that failed to dissolve.6.3 The volume of cuprammonium solution used is alsocritical. The effect of incorrect volume on viscosity is shown inTable 2.6.4 Use the temperature correction factors given in Table 3to correct the cuprammonium viscosities to 25C, assumingthat a 1C increase c

22、auses a 3 % decrease in the measuredviscosity of the solution. Correction for temperatures off bymore than 5C is not recommended. Samples should beretested, ensuring than the CuAm solution is within tempera-ture limits.7. Apparatus7.1 Testing Laboratory, maintained at 25 6 2C.7.2 Picker, suitable fo

23、r shredding pulp without damaging it.The picker must have provisions that permit sample remainingafter picking is completed to be blown out with compressed air.7.3 Drier, suitable for pulp sample that dries the pulp withhot air whose temperature is never permitted to get higher that120C.7.4 Analytic

24、al Balance, capable of weighing to 60.001 g.7.5 Bottles, wide mouth, glass, for use with an approxi-mately No. 5 rubber stopper, and with a capacity of at least 120mL (4 oz). The type of bottle must be selected such that it issuitable for dissolving pulps in cuprammonium solution asspecified in this

25、 test method.7.6 Steel Balls, chrome alloy, Grade 25, 3.2-mm (18-in.)diameter.7.7 Automatic Pipet, special made, capable of delivering 976 1 mLof CuAm solution, which is part of the cuprammoniumsolution filling system (see Fig. 1).7.8 Rubber Stopper Assembly, (see Fig. 2).7.9 Vacuum Source, capable

26、of pulling a vacuum of 686 mmHg.7.10 Shaker, capable of shaking bottles of cuprammoniumsolution containing pulp. The shaker is to hold the bottles in ahorizontal position, and its design and operation should be suchthat in-process pulps will be completely dissolved after 20 minof shaking.7.11 Transf

27、er Assembly, for transferring thecuprammonium-cellulose solution from the bottle to the vis-cosity tube (see Fig. 3).7.12 Viscosity Tube, specially made (see Fig. 4).7.13 Glass Viscosity Beads, for ACS cuprammonium vis-cosity determination. These beads are to be ground to adiameter that causes the v

28、iscosity of each second of bead fallTABLE 1 Effect of Weight Errors on Viscosity ErrorPulp Weight Percent Viscosity ErrorError, % Underweight Overweight1 3.8 3.92 7.4 8.05 17.4 21.110 31.8 45.6TABLE 2 Effect of Volume Errors on Viscosity ErrorVolume Percent Viscosity ErrorError, (mL) Low Volume High

29、 Volume1 4.0 3.92 8.2 7.65 21.8 17.910 48.3 32.6TABLE 3 Temperature Correction FactorsTemperature Correction FactorError, C Low Temperature High Temperature1 0.971 1.0302 0.943 1.0613 0.915 1.0934 0.888 1.1265 0.863 1.159FIG. 1 Solution Filling SystemD6188 172time in cuprammonium-cellulose solution

30、to equal 22 cP. (Thiswill mean that a sample that has a bead fall time of 10 s willhave a viscosity of 220 cP, and a sample that has a bead falltime of 50 s will have a viscosity of 1100 cP). Since the densityof various shipments of glass beads will vary somewhat, thediameter of the beads will have

31、to be varied to compensate forthe variation in the density of the glass. Generally the beadswill be about 3.3 mm in diameter, and they will weigh about0.046 g.7.14 Moisture BalanceApparatus to determine the dryweight of cellulose.7.15 pH Meter.7.16 Viscosity Tube Holder/Lighting AssemblyThis deviceh

32、olds the viscosity tube vertically with a bright light behind thetube so that the bead falling through the cuprammoniumsolution can be easily seen.7.17 Bead Centering ApparatusThis consists of a smallcorrosion resistant funnel topped tube having an internaldiameter just sufficient to permit the bead

33、s to fall throughfreely.7.18 Timer, accuracy/precision: 630sover1h.7.19 Plastic Sieve, with 0.250 mm openings, the same as USAlternate No. 70, Tyler 60 mesh sieve.7.20 Plastic Container, 2500 to 3500 mL graduated poly-ethylene beaker with handle.8. Reagents and Materials8.1 Cuprammonium Solution, co

34、ntaining 20 6 1 g/L ofcopper (expressed as copper) and 200 6 2 g/L of ammoniumhydroxide (expressed as ammonium).8.2 Water, potable.8.3 Water, reagent (in accordance with Specification D1193)with an electrical resistance of at least 1 000 000 -cm. Thiswater is used to determine the pH of the film lef

35、t after acidwashing.9. Hazards9.1 CuAm solution is corrosive, and thus harmful to the skinand eyes. Wear safety glasses or goggles while working withthis solution. Gloves and laboratory coat or chemical apron arerecommended.10. Sampling10.1 The sample for this test may consist of a wet pulp or adry,

36、 finished product sample. Take a representative portion ofthe pulp sample that contains at least 10 and not more than25 g of dry pulp.10.2 If the sample is an in-process pulp sample, thoroughlywash out any process chemicals (acids, bases, or bleach),which may be present. Drain the excess water out o

37、f the wetpulp sample (see 10.3).10.3 If any sample is above 40 % consistency, wet it withdemineralized water. If the sample is below 20 % consistency,hand squeeze it or press it until the consistency is between 20to 40 %.10.4 Seven sample sizes are authorized by this test method.These sizes, in g, a

38、re 0.85, 1.00, 1.25, 1.50, 2.20, 2.40, and3.50. Select the sample size which will be used for the test.Generally, select a sample size which will give a CuAmviscosity between 15 and 60 s. Never use a sample size thatgives a CuAm viscosity of less than 10 or more than 100 s. (Ifa test result is not w

39、ithin these limits, a new sample size shouldbe selected.)10.5 In order to ensure that traces of the last sample passedthrough the picker will not contaminate the new sample, pickenough of the present sample that an amount equal to at least1 g of dry pulp has passed through the picker. Discard all of

40、this portion of the sample. Then, pick enough of the sample tocarry out the viscosity test. Immediately after each sample hasbeen passed through the picker, turn on the compressed airgoing into the picker for at least 2 s. (This is to blow out asmuch as possible of the sample before it has time to d

41、ry andstick to the surfaces of the picker.)10.6 Dry the picked sample with air as follows:10.6.1 Temperature does not exceed 120C, and10.6.2 Time does not exceed 20 min.10.7 Weigh the sample in a manner that will consistentlygive weighed samples which contain dry pulp weights withinthe specification

42、s of Table 4.10.8 More accurate and precise results will be obtained ifthe pulp sample is conditioned to an equilibrium moisturecontent and the consistency of the sample determined bymoisture balance. This modification provides better weightcontrol, but is not suited for rapid turn-around process co

43、ntrol.11. Calibration and Standardization11.1 Select control pulp samples for which a relatively largesupply is available. Ensure that the cuprammonium viscositiesFIG. 2 Rubber Stopper Assembly In BottleD6188 173of these samples are sufficiently different so that differentsample weights are required

44、. Determine the cuprammoniumviscosity of each sample using exactly the same procedure thatwould be used for testing unknown samples. Record thecuprammonium viscosity in a log book. Keep a separatecontrol chart of the cuprammonium viscosity values (or loga-rithm of the values) for each of the samples

45、. Measure thesecontrol samples at a convenient frequency.12. Conditioning/Preparation12.1 Conditioning of dry samples to an equilibrium mois-ture content will give more accurate and precise results.12.2 It is usually necessary to treat bottles, stopperassemblies, and viscosity tubes with a solution

46、of sulfuric acidto coagulate the CuAm-cellulose solution before this apparatuscan be cleaned. (WarningIt is very important that thisapparatus be thoroughly washed to remove all of the sulfuricacid before it is dried. If there is a small amount of sulfuric acidremaining on the surface of any apparatu

47、s when it dries, a thinfilm of sulfuric acid will remain on the surface of theapparatus.)13. Procedure13.1 Carry out the following operations in a room main-tained at 25 6 2C (77 6 3.6F).13.2 This test method defines clean, dry bottles; clean, drystopper assemblies; and clean, dry viscosity tubes as

48、 ones thatappear to be clean, do not have water or water droplets in or onthem, and that will deliver water with a pH not lower than 5.0or higher than 7.0 when their surfaces are washed withdemineralized water.13.3 In carrying out this part of this test, note that CuAmsolution is present in glass tu

49、bes and rubber or plastic hoseunder a slight pressure. (WarningCuAm solution is harmfulto the skin, and eyes (see 9.1).13.4 Place the weighed sample of pulp in a clean, dry bottle(see 7.5), and add 25 6 10 clean, dry steel shot to the bottle.Tightly insert a clean dry rubber stopper assembly containing ashort glass tube with a short rubber hose connected to the topof the glass tube. It may be desirable to dampen the wall of thestopper with water so that it can be inserted tightly, but do nothave any liquid water on or in the rubber stopper assemb