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IS 6213-4 (1971): Methods of Test for Pulp, Part IV:Determination of Viscosity of Pulp [CHD 15: Paper and itsproducts]

IS : 6213 ( Part IV) - 1971

Indian Standard METHODS OF TEST FOR PULP

PART IV DETERMINATION OF VISCOSITY OF PULP

( Second Reprint AUGUST 1997 )

UDC 676.1 : 676.014.82

0 Copyright 1972

BUREAU OF INDIAN STANDARDS MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARC;

NEW DELHI 110002

Gr 4 June 1972

IS : 6213 ( Part IV) - 1971

Indian Standard METHODS OF TEST FOR PULP

PART IV DETERMINATION OF VISCOSITY OF PULP

Paper Sectional Committee, CDC 15

Chairman

SHRI N. NARA~IMHAN

C-48, South Extension, New Delhi 49

Members Representing

SHRI N. J. ARDESHIR All India Federation of Master Printers, New Delhi SHRI R. VENKATESWARAN ( Alternate )

SHRI V. J. BAKRE Central Board of Excise & Customs SHRI N. K. CHOWDHURI ( Alternate )

SHRI S B. BATRA Stationery & Office Equipment Association of India, Calcutta

SHRI S. K. BOSE National Test House, Calcutta SHRI S. P. MOULICK ( Alternate)

SHRI A. P. CHAKRAVARTI Ministry of Defence ( R & D ) SHRI A. C. DAS GUPTA Chief Controller of Supply, Printing and Stationery,

New Delhi SHRI C. E. J-s ( Alternate)

SHRI RAMESH DATT The Metal Box Co of India Ltd, Calcutta SHRI B. K. DATTA GUPTA Ministry of Defence ( DGI )

SHRI S. S. RAO ( Alternate) SHRI K. L. GHOSH Regional Research Laboratory ( CSIR ),

Bbubaneswar SHRI G. H. GONDHALEKAR Handmade Paper Institute, Poona

SHRI K. J. SOMAN (Alternate) DR S. R. D. GUHA Forest Research Institute & Colleges, Dehra Dun Srmr S. N. GUHARAY Sree Saraswaty Press Ltd, Calcutta SHRI DEVENDRA KUMAR JAIN Federation of Paper Traders Association, Bombay

SHRI ARVIND CHIMANLAL SHAH ( Alternate ) SHRI D. D. JATKAR Regional Research Laboratory ( CSIR ), Hyderabad

SHRI M. S. KUMARASWAMY ( Alfernate ) SHRI M. A. JHANGIANI Directt;;te General of Supplies & Disposals, New

SHRI i%f. N. SARKAR ( Alternate ) SHRI S. K. KESHAVA India Tobacco Company Ltd, Calcutta

SHRI G. S. WADE ( Alternate) DR V. S. K. NAIR Indian Paper Mills Association, Calcutta

SHRI K. S. BHARGAVA ( Alternate ) SHRI D. P. NATHANI Calcutta Paper Traders Association, Calcutta

SWRI D. K. KOTHARI ( Alternate )

.‘. ( Continued on page 2 )

BUREAU OF INDIAN STAkDARDS MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG

NEW DELHI 110002 .

IS : 6213 ( Part IV ) - 1971

( Continued.from page 1 )

Members

SHRI N. B. PODDAR DR N. V. C. RAO

SHRI A. N. RAO ( Alternate ) DR D. C. TAPADAR SHRI M. S. TYAGI SHRI D. DAS GUPTA,

Director ( Chem )

All India Small Paper Mills Association, Bombay Directorate General of Technical Development, New

Delhi / f

Institute of Paper Technology, Saharanpur Indian Paper Makers’ Association, Calcutta Director General, IS1 ( fi-ojicio Member )

sccretasy f

SHRI SATISH CHANDER

Deputy Director ( Chem ), IS1

Methods of Test Subcommittee, CDC 15 : 2

Convener

DR D. C. TAPADAR

Members

Institute of Paper Technology, Saharanpur

SHRI N. K. NAITHANI ( Alfcrnate to Dr D. C. Tapadar )

SHRI V. J. BAKRE Central Board of Excise & Customs SHRI N. K. CHOWDHURI ( Alternate )

SHRI K. S. BHARGAVA Rohtas Industries Limited, Dalmianagar SHRI 0. L. DUGGAL The Ballarpur Paper & Strawboard Mills Ltd ( Shrce

SHRI V. D. GUPTA (Alternate ) Gopal Division ), New Delhi

SHRI N. S. JA~PAL S~nr MAN MOHAN SINCH

West Coast Paper Mills Ltd, Sangurnagar Forest Research Institute & Colleges, Dehra Dun

SHRI G. M. MATHUR ( Alternate ) SHRI MAJEED MOHIUDDIN Orient Paper Mills Ltd, Calcutta

SHRI N. K. MOHATTA ( A&mate )

2

IS : 6213 ( Part IV ) - 1971

Indian Standard METHODS OF TEST FOR PULP

PART IV DETERMINATION OF VISCOSITY OF PULP

0. FOREWORD ,I 0.1 This Indian Standard ( Part IV ) was adopted by the Indian Standards Institution on 20 July’ 1971, after t,he draft finalized by the Paper Sectional Committee had been approved by the Chemical Division Council.

0.2 For obtaining good quality of paper, it is essential that the pulp which goes into the manufacture of paper is properly cooked and bleached. Formulation of this standard had been taken up in order to guide the people working in pulp and paper mills regarding the methods to be adopted for pulp analysis.

0.3 In this test method, a temperature of 20°C has been prescribed instead of the usual standard temperature of 27°C. This has been done since it was felt that it would not be possible to retain the desired concentration of copper and ammonia in cuprammonium solution at 27°C.

0.4 In reporting the result of a test or analysis made in accordance with this standard, if the final value, observed or calculated, is to be rounded off, it shall be done in accordance with IS : 2-1960*.

1. SCOPE

1.1 This standard ( Part IV ) prescribes the methods of test for determina- tion of viscosity of pulp in cuprammonium and cupriethylenediamine solution.

2. QUALITY OF REAGENTS

2.1 Unless otherwise specified, pure chemicals and distilled water (see IS : 1070-196OT ) freshly boiled and cooled, shall be employed in the tests.

NOTE - ‘ Pure chemicals ’ shall mean chemicals that do not contain impurities which sect the results of analysis.

3. CUPRAMMONIUM METHOD

3.0 General- This method describes a simple but sufficiently accurate and reproducible method to serve as a routine test. This method is appli- cable to both bleached and unbleached pulps.

*Rules for rounding off numerical values ( revised ) , $Ypecification for water, distilled quality ( revircd ).

3

IS : 6213 ( Part IV ) - 1971

3.1 Apparatus

3.1.1 Constant Temperature Bath -capable of being maintained at 20.0 f O*l”C.

3.1.2 Viscosity Tube -The viscosity tube, as shown in Fig. 1, consists of a heavy alkali-resistant glass tube with an internal diameter of 10 mm and a total length of 270 mm. It terminates at the base in a capillary tube 25 mm long and 0.9 mm inside diameter. It is closed at the top with a rubber stopper carrying another capillary tube which is fitted with a rubber tube and a pinch cock and at the bottom with a rubber tube and pinch cock. The wide ortion is etched with three rings at distances’of 242, 122 and 62 mm rom the flat end of the viscosity tube. A wedge- P shaped monel metal cylinder 25 mm long with a notched base is inserted ‘* in the tube which is then closed. Excess of solution is eliminated through the top capillary tube.

3.2 Reagents

3.2.1 Cuprammonium Solution - Prepare a solution of 500 g of copper sulphate ( CuS0,.5H,O ) in one litre of water. Warm the solution till the copper sulphate dissolves. Then add liquor ammonia ( not less than 25 percent concentration) slowly with stirring till the precipitation of copper hydroxide [ Cu ( OH )s ] is complete and the solution is faintly alkaline to litmus. Let the precipitate settle down. Wash by decantation with hot distilled water till the washings are free from sulphate ions ( test with barium chloride solution ) . Transfer the washed copper hydroxide slurry in 1 litre of liquor ammonia kept in a bath at 20°C and make the volume to 6 litres with ammonia. Close the cork of the stock bottle and allow the solution to saturate with copper hydroxide for 2 to 3 days. The final solution should have a copper content of 14.8 to 15.2 g/l and ammonia content of 190 to 210 g/l. The stock solution could be used for 2 to 3 months if properly stored.

3.2.1.1 Testing of copper concentration - Take 10 ml of the clear stock solution in a conical flask and dilute with 25 ml of water. Boil the solution until no more ammonia is given off. Add 5 ml of nitric acid ( 1 : 1 ) and

c

boil until red fumes are expelled. Then add 2 ml of bromine water and boil until bromine is expelled. Dilute to 75 ml and carefully add ammo- nium hydroxide until the solution becomes just alkaline. Add a slight _ excess ( 4 to 5 ml ) of glacial acetic acid, cool to room temperature and add 10 ml of 30 percent potassium iodide solution. Titrate with 0.1 N sodium thiosulphate solution until the yellow colour of free iodine is nearly gone, then add starch indicator and continue the titration cautiously until on addition of another drop the blue colour due to free iodine disappears:

Copper content in g/l = O-636 V

where

V = volume of 0.1 N sodium thiosulphate solution used.

4

I6:6213(Par’cIV)-1973.

RING \

RING,

-

RING--.,

.

‘1 109

T 62

1

PINCH COCK

-r

270

PINCH COCK

5

IS : 6213 ( Part IV ) - 1971

3.2.1.2 Testing for ammonia concentration -Take 25 ml of O-5 N hydro- chloric acid in a dish and add a few drops of methyl red solution. Take cuprammonium solution to be tested in the burette and let its tip dip in the solution in the dish. Add the solution drop by drop till the colour is slightly bluish:

200 Concentration of ammonia in g/l = x - ( O-536 Y)

where

X = copper solution consumed in ml, and

Y = concentration of copper in solution g/l.

3.3 Procedure -Take a representative sample of the pulp. portion of it for the determination of moisture content.

Keep one Weigh shreded

pulp equivalent to 0.32 g of the oven-dry pulp correct up to 0.1 mg. Place the same in the small stainless steel tube and moisten it with 2 ml of distilled water. Crush it with the rammer till the fibres separate. For bleached pulp crushing or ramming for 1 to 2 minutes is sufficient but for unbleached pulps it takes Ionger time to separate the fibres. Add 28 ml of the standard cuprammonium solution at 20°C ( 14.8 to 15.2 g/l of copper and 190 to 210 g/l of ammonia ) to it and stir the mixture exactly for 4 minutes. During stirring at high speed the pulp dissolves in cupram- monium solution. Close the mouth of the tube with a cork and keep it in the constant temperature bath at 20°C for 5 minutes. Pour the contents of the tube in the viscosity determination tube kept in the water bath at 20°C and note the time of drainage of the solution from initial mark Uto V and V to W. These two times should not differ greatly if the solution is homogeneous.

3.4 Calculation - Calculate the viscosity of the solution from the formula:

Ir =ctd

where

p = viscosity of solution i4 centipoises, c - pipette constant, t = time of drainage of solution in seconds, and

\

d = density of plup solution.

Carry out the test in duplicate. The two test results sholild not vary by 2 to 3 percent.

3.4.1 Determination of Pipette Constant ‘19 - Take standard glycerine solution (spgr l-21 at 20°C). meter at 20°C. Fill

Determine its specific gravity by means of a pykno- it in the viscosrty tube kept in water-bath at 20°C

and note the time of drainage from the initial mark U to V and V to IV. Calculate the value of c from the aboveformula; calibrate the apparatus with liquids of known viscosity every time before use.

a

c

t1

s

IS : 6213 ( Part IV) - 1971

4. CUPRIETHYLENEDIAMINE METHOD

4.0 General-This method describes precise and rapid procedure for determination of viscosity of cellulose solutions using cupriechylenediamine as solvent. This method may be used for the determination of viscosity of both bleached and unbleached pulps.

4.1 Apparatm

4.1.1 Cylinder of Nitrogen Gas -fitted with a reducing valve to give gas at a pressure of 0.14 to 0.21 kgf/cmz.

4.1.2 Constant Temperature Bath - suited for holding Feqske pipettes at a constant temperature within fO*l”C.

4.1.3 Viscosity Pijette - made of heat and alkali-resistant glass having the following characteristics ( see Fig. 2 ):

S&z Number Bore of Capillary mm

50 0.42 f 0.02

100 0.63 f 0.02

200 1.02 f 0.02

300 1.26 -j= 0.02

4.00 1938 f 0.02

500 3.10 f 0.05

Range of Time to Flow Viscositp Range seconds ten tipoise

300 to 1 500 0.8 to 3

200 ,, 700 3 1, 10

100 ,, 700 10 ,, 70

100 ,) 700 25 ,, 125

100 ,, 700 120 ,, 850

100 ,, 700 800 ,, 5600

4.1.3.1 Calibration of viscosity Pipette - In order to calibrate, oils of known viscosity in the desired viscosity range are used. The pipette constant c is calculated as given below:

cc

I C=td

where

c = pipette constant,

CL = viscosity in centipoises,

t = time in seconds for meniscus to pass between the etched lines around capillary, and

d = density of the solution.

7

IS : 6213 ( Part IV ) - 19fl

: ,

2d

c

-

-12*5 6

All dimensions in millimetres.

FIG. 2 VISCOSITY PIPETTE

8

IS : 6213 ( Part IV ) - 1971

The constant c is determined with the help of oil of known viscosity and density at 27°C in the recommended range as mentioned below:

First of all the viscometer in its inverted vertical position is loaded with the capillary side submerged in standard oil of known viscosity and density. Then the suction to the other arm of the instrument is applied and both small bulbs on the capillary arm are filled with oil. Then the liquid into the working capillary is brought up to the etched mark. After pipette is filled, it is rotated to its normal vertical position and is placed in a constant temperature water-bath maintained at 27.0 & 0.1%. In order to attain the bath temperature the liquid is drained in the lower reservoir during the time required for it. It will take about 15 minutes to reach the bath temperature. When this temperature is obtained, determine the efflux time for the meniscus to pass from the mark between the two bulbs to the mark below the lower bulb. Make at least two determinations. The pipette constant is calculated by dividing the known viscosity of the oil by the product of its density and et&x time.

4.1.4 Dissolving Tube - The glass tube used. for dissolving the pulp is shown in Fig. 3. The stirrer consists of stainless steel rod approximately 3 mm in diameter, bent as shown in Fig. 3.

4.2 Reagents

4.2.1 Sodium Hydroxide Solution - 20 percent. Dissolve 200 g of sodium hydroxide in 800 ml of distilled water.

4.2.2 Ethylenediamine - 70 percent, technical grade.

4.2.3 Standard Viscosity Oils - oils of known viscosity for calibration of pipette.

4.2.4 Cujwiethylenediamine Solution - This solution is prepared as given in 4.2.4.1 to 4.2.4.4.

. 4.2.4.1 Dissolve 250 g of copper sulphate ( CuS0,.5H,O ‘) in approxi- mately 2 litres of hot distilled water. Boil it and add with vigorous agitation concentrated ammonium hydroxide until the solution is faintly alkaline to litmus paper. This would approximately require 115 ml of ammonium hydroxide. Allow the precipitate to settle and wash by de- cantation; four times with hot water and twice with cold water. Add sufficient water to make the volume of the slurry to 1.5 litres. Cool it to below 20°C preferably up to 10°C. Add slowly, with vigorous stirring, 50 ml of cold 20 percent sodium hydroxide solution. Wash the precipitated cuperous hydroxide with distilled water by decantation until washings are colourless to phenolphthalein indicator and no precipitate appears with the addition of barium chloride.

9

IS : 6213 ( Part N ) - 1971

All dimensions in millimetrcs.

FIG. 3 DISSOLVING TUBE

4.2.4.2 Add sufficient water to wash cuperous hydroxide slurry to make the volume to 500 ml in the bottle of;the shape shown in Fig. 4. The bottle is equipped with a rubber stopper carrying two glass tubes, one of which (A) is straight and extends to within approximately to 5 cm of the bottom of the bottle and the other has two right angle bends (B and C ). One of the side tubes (B or C) is connected to a suction source and the other to the nitrogen supply.

4.2.4.3 Exhaust the air in the bottle with the help of the pump and refill the bottle with nitrogen at 0.14 kgf/cm* pressure. Repeat this exhaus- tion and refilling the bottle three times. Make partial vacuum in the bottle and add 160 ml of 70 percent ethylenediamine solution taking care that no air enters the bottle. This is accomplished by inserting a funnel in the rubber tube attached to the longer glass tube of the bottle and opening the pinch cock just enough to allow the ethylenediamine to be drawn into the bottle. Since considerable heat is evolved during the initial phase of

10

IS : 6213 ( Part IV ) - 1971

Z-GLASS TUBES

v GLASS BOTTLE

FIG. 4 SOLUTION OR STOCK BOTTLE

> the reaction, it is desirable to keep the cold water running over the bottle. Repeat the evacuation of the gas in the bottle and refill it with nitrogen at 0.14 kgf/cms pressure three times. Rotate the bottle and the contents for 12 to 16 hours on a rotary shaker moving at 5 to 10 rev/min while keeping the pinch cocks closed. Remove the bottle and allow it to stand for at least 8 hours to thoroughly settle the excess cuperous hydroxide sludge.

4.2.4.4 Standardkation of cupriethylencdiamine solution

co@er - Take 25 ml of clear liquor in a volumetric flask and dilute to 250 ml. Take 25 ml of the diluted aliquot and add approximately 3 g of potassium iodide. Acidify it with 4 N sulphuric acid and titrate it with O-1 N sodium thiosulphate solution using starch as the indicator. Add 10 ml of 20 percent ammonium cyanide solution just before the end point

11

IS : 6213 ( Part IV) - 1971

to intensify the colour at end point. Calculate the molarity of copper in original solution as follows:

Molarity of copper = O-04 x volume in ml of 0.1 N sodium thiosul- phate solution required to reach the end point

Ethylenediamine - Take another 25 ml of diluted aliquot and add 75 ml of distilled water and two drops of methyl orange indicator. Titrate it with normal acid solution to faint pink colouration. The colour change of the solution during the titration passes from dark blue to light blue to slate grey and finally develops a pink tinge. Calculate the alkalinity in hydrogen ion equivalents as follows:

Alkalinity in hydrogen ion equivalents = 0.4 x volume in ml of normal acid required for titration

B - 2A Ratio of ethylenediamine to copper ( R ) = --

2A

where

R = ratio of ethylenediamine to copper,

B = alkalinity in hydrogen ion equivalents, and

A = molarity of copper.

4.2.4.5 Dilution - In order to keep the molar ratio of ethylenediamine between 1.85 : 1 and 2.00 : 1 the solution shall be properly prepared by care- ful compliance with the directions given earlier. If anyhow the ratio exceeds 2.00 : 1, fresh cuperous hydroxide is added and the agitation is repeated. The standardization of the solution is as given earlier in 4.2.4.4.

When the proper molar ratio of ethylenediamine to copper is obtain- ed, the exact amount of the original supernatant solution is forced by nitrogen pressure into stock bottle. Add sufficient distilled water to give 0.500 M of copper concentration. The copper concentration should be checked by further analysis as mentioned above. The final concentration of the copper should be within O-5 percent of the prescribed value. When the solution having been checked for accuracy, the stock bottle should be evacuated and flushed with nitrogen three times and the solution stored under nitrogen at O-14 kgf/cni2 pressure.

4.2.5 Procedure - Take air-dry pulp equivalent to O-125 g of moisture- free pulp and place in the dissolving tube. Add 25 ml of cupriethylene- diamine solution ( 0.500 M in copper ) and stir the solution for 15 minutes rotating the stirrer approximately at 400 rev/min. Remove the stirrer and take a portion of the solution in the viscosity pipette in the same way as given in 4.1.3 while calibrating the viscosity pipette.. Determine the ef%.rx

12

IS : 6213 ( Part IV ) - 1971

time at 27 & O-l%. Make at least two determinations and check that they are within + 0.2 seconds.

Viscosity of 0.5 percent pulp solution is calculated by the formula:

p=ctd

where

P = viscosity of solution in centipoises,

c = pipette constant,

t = ef%x time in seconds, and

d = density of the pulp solution.

13

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