1、Designation: D 6188 97 (Reapproved 2003)Standard Test Method forViscosity of Cellulose by Cuprammonium Ball Fall1This standard is issued under the fixed designation D 6188; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year o
2、f last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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 viscosi
3、tyof cuprammonium (CuAm) 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 AmericanChem
4、ical Society (ACS)2.1.2 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 stand
5、ard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:D 1193 Specification for Reagent Water3D 1695 Terminology of Cellulose and Cellulose Deriva-tives4E 438 Specification for Glasse
6、s in Laboratory Apparatus53. Terminology3.1 This standard terminology of cellulose and cellulosederivatives, see Terminology D 1695.4. 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
7、are wetted 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 ob
8、tained. 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 t
9、ransferred 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 ap
10、art. 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 “
11、as is” 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 determinatio
12、n of 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.)5.3 Cotton and high molecul
13、ar 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 reduction inviscosity. Therefore, limit the maximum temperature of the airused to dry the sample to 120C an
14、d the maximum drying timeto 20 min to keep viscosity loss to a minimum. All in-process1This test method is under 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 Derivati
15、ves.Current edition approved May 10, 2003. Published June 2003. Originallyapproved in 1997. Last previous edition approved in 1997 as D 6188 - 97.2Carver et al., “A Standard Method for Determining the Viscosity of Cellulosein Cuprammonium Hydroxide,” Industrial and Engineering Chemistry, AnalyticalE
16、dition, Vol 1, No 1, 1929, pp. 49-51.3Annual Book of ASTM Standards, Vol 11.01.4Annual Book of ASTM Standards, Vol 6.03.5Annual Book of ASTM Standards, Vol 14.02.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.samples must be washed
17、to remove cooking and bleachingchemicals, because the presence of chemicals while drying 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
18、a smallamount fails to dissolve, the viscosity will be incorrect by atleast the percentage 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 giv
19、en in Table 3to correct the cuprammonium viscosities to 25C, assumingthat a 1C increase causes 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
20、 limits.7. Apparatus7.1 Testing Laboratory, maintained at 25 6 2C.7.2 Picker, suitable for 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
21、pulp withhot air whose temperature is never permitted to get higher that120C.7.4 Analytical 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
22、such that it issuitable for dissolving pulps in cuprammonium solution asspecified in this 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 mL of CuAm solution, which is part of the cuprammoniumsolution filling
23、 system (see Fig. 1).7.8 Rubber Stopper Assembly (see Fig. 2).7.9 Vacuum Source, capable 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
24、suchthat in-process pulps will be completely dissolved after 20 minof shaking.7.11 Transfer 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 cuprammon
25、ium vis-cosity determination. These beads are to be ground to adiameter that causes the viscosity of each second of bead falltime in cuprammonium-cellulose solution 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
26、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 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
27、will weigh about0.046 g.7.14 Moisture BalanceApparatus to determine the dryweight of cellulose.7.15 pH Meter.TABLE 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
28、 Viscosity ErrorVolume Percent Viscosity ErrorError, (mL) Low Volume High 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
29、 Solution Filling SystemD 6188 97 (2003)27.16 Viscosity Tube Holder/Lighting AssemblyThis de-vice holds the viscosity tube vertically with a bright lightbehind the tube so that the bead falling through the cupram-monium solution can be easily seen.7.17 Bead Centering ApparatusThis consists of a smal
30、lcorrosion resistant funnel topped tube having an internaldiameter just sufficient to permit the beads to fall throughfreely.7.18 Timer, accuracy/precision:6 30sover1h.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
31、 mL graduated poly-ethylene beaker with handle.8. Reagents and Materials8.1 Cuprammonium Solution, containing 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 SpecificationD 1193) with an
32、electrical resistance of at least 1 000 000V-cm. This water is used to determine the pH of the film leftafter acid washing.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 che
33、mical apron arerecommended.10. Sampling10.1 The sample for this test may consist of a wet pulp or adry, finished product sample. Take a representative portion ofthe pulp sample that contains at least 10 and not more than 25g of dry pulp.10.2 If the sample is an in-process pulp sample, thoroughlywash
34、 out any process chemicals (acids, bases, or bleach),which may be present. Drain the excess water out of 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 consisten
35、cy is between 20to 40 %.10.4 Seven sample sizes are authorized by this test method.These sizes, in g, are 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
36、 a sample size thatgives a CuAm viscosity of less than 10 or more than 100 s. (Ifa test result is not within 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 prese
37、nt sample that an amount equal to at least1 g of dry pulp has passed through the picker. Discard all ofthis 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
38、 picker for at least 2 s. (This is to blow out asmuch as possible of the sample before it has time to dry 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 m
39、anner that will consistentlygive weighed samples which contain dry pulp weights withinthe specifications 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 balan
40、ce. This modification provides better weightcontrol, but is not suited for rapid turn-around process control.11. Calibration and Standardization11.1 Select control pulp samples for which a relatively largesupply is available. Ensure that the cuprammonium viscositiesof these samples are sufficiently
41、different so that differentsample weights are required. 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
42、 (or loga-rithm of the values) for each of the samples. 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, s
43、topper assem-blies, and viscosity tubes with a solution of sulfuric acid tocoagulate 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
44、of sulfuric acidFIG. 2 Rubber Stopper Assembly In BottleD 6188 97 (2003)3remaining on the surface of any apparatus 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).
45、13.2 This test method defines clean, dry bottles; clean, drystopper assemblies; and clean, dry viscosity tubes as 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 w
46、ithdemineralized water.13.3 In carrying out this part of this test, note that CuAmsolution is present in glass tubes 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
47、), 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, b
48、ut do nothave any liquid water on or in the rubber stopper assembly.Connect the end of the rubber tubing to the filling assemblyillustrated in Fig. 1, and apply a vacuum of at least 660 mm Hgfor at least 3 s. to the bottle containing the sample. Then,without loosing the vacuum in the bottle, add 97
49、6 1mLofcuprammonium solution to the bottle. Be sure that there is noCuAm solution in the filling system below the stopcock on theautomatic pipet before the addition is begun, and be sure thatall of the CuAm solution in the filling system is added to thebottle and that none remains in any part of the filling system.However, do not let air into the bottle after all of the CuAmsolution has entered the bottle. (Never apply vacuum to thebottle after the addition of the CuAm solution is begun, sincethis may result in the loss of several millilitres of the measured97 mL of
