Disclosure to Promote the Right To Information

Whereas the Parliament of India has set out to provide a practical regime of right to information for citizens to secure access to information under the control of public authorities, in order to promote transparency and accountability in the working of every public authority, and whereas the attached publication of the Bureau of Indian Standards is of particular interest to the public, particularly disadvantaged communities and those engaged in the pursuit of education and knowledge, the attached public safety standard is made available to promote the timely dissemination of this information in an accurate manner to the public.

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“Invent a New India Using Knowledge”

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“Step Out From the Old to the New”

“जान1 का अ+धकार, जी1 का अ+धकार”Mazdoor Kisan Shakti Sangathan

“The Right to Information, The Right to Live”

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“Knowledge is such a treasure which cannot be stolen”

“Invent a New India Using Knowledge”

है”ह”ह

IS 6918 (2002): Mercaptobenzothiazole [PCD 13: Rubber andRubber Products]

IS 6918:2002

x- \\ . \ \Wxlwl’wwilvf —.

( WRTT @tWT )

Indian Standard

MERCAPTOBENZOTHIAZOLE — SPECIFICATION

(First Revision )

ICS 83.040.01

0 BIS 2002

BUREAU OF INDIAN STANDARDSMANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG

NEW DELHI 110002

April 2002 Price Group 7

Rubber Products Sectional Committee, PCD 13

FOREWORD

This Indian Standard ( First Revision) was adopted by the Bureau of Indian Standards, after the draft finalized bythe Rubber Products Sectional Committee had been approved by the Petroleum, Coal and Related Products DivisionCouncil.

Mercaptobenzothiazole is a semiultra nonstaining accelerator used in compounding of rubber. Mercaptobenzothiazoleis soluble in acetone, ethyl alcohol, chloroform and dilute alkalis, partially soluble in benzene and insoluble inwater and gasoline. Since it imparts bitter taste to the vulcanizate, mercaptobenzothiazole should not be used forthose rubber parts which come in contact with the food products. Besides specifying chemical requirements, thestandard includes a recommended procedure for evaluating the material by means of a standard compoundingand vulcanizing procedure.

This standard was published in 1972. In this version ( first revision ) requirements for melting point and assayhave been increased. Residue on 63 micron and surface coating for coated grade have been added. Requirementfor loss on heating, sulphated ash and manganese have been tightened.

The composition of the Committee responsible for formulation of this standard is given in Annex M.

For the purpose of deciding whether a particular requirement of this standard is complied with, the final value,observed or calculated, expressing the result of a test of analysis, shall be rounded off in accordance with1S2:1960 ‘Rules for rounding off numerical values ( revised)’. The number of significant places retained in therounded off value should be the same as that of the specified value in this standard.

.,&

IS 6918:2002

Indian Standard

MERCAPTOBENZOTHIAZOLE —

(First Revision )1 SCOPE

This standard prescribes the requirements, methodsof sampling and test for mercaptobenzothiazoleintended for use as an accelerator in rubbercompounds.

2 REFERENCES

The following Indian Standards contain provision whichthrough reference in this text, constitute provisionsof this standard. At the time of publication, the editionsindicated were valid. All standards are subject torevision, and parties to agreements based on thestandard are encouraged to investigate the possibilityof applying the most recent editions of the standardsindicated below:

IS No.

1070:1992

1675:1971

1683:1994

3399:1993

3400

(Part 1 ): 1987

(Part 2):1995

3660

(Part 7): 1989

( Part 8 ): 2000

4588:1988

7086 ( Part 1 ) :1973

Title

Reagent grade water ( third

revision )

Stearic acid, technical (first

revision )

Barytes for rubber industry ( second

revision )

Zinc oxide for rubber industry( second revision)

Methods of test for vulcanizedrubbers:

Tensile stress — Strain properties( second revision )

Hardness ( second revision )

Methods of test for natural rubber:

Determination of Mooney viscosity( NR :8 ) ( second revision )

Mixing and vulcanizing of rubber instandard compound ( NR: 9 )( second revision)

Rubber, raw, natural ( third

revision )

Method of sampling and test forrubber compounding ingredients

3 REQUIREMENTS

3.1 Description

The material shall be in powder — non coated or coated

1

SPECIFICATION

grade and pellet form free from any visible impurities.

3.2 Chemical Requirements

The materialshallcomplywith the chemicalrequirementsgiven in Table 1 when tested according to the qualityof water and chemicals as given in Annex A.

3.3 Performance Requirement

The material when compounded and tested as givenin Annex K shall have its properties comparable, withinthe limits prescribed in K-4.1, with those of the samplecomplying with the requirements of3.1 and 3.2 andapproved previously by the purchaser.

4 PACKING AND MARKING

4.1 Packing

The material shall normally be packed in 20 or 25 kgpacks of multiwall paper bags or as agreed to betweenthe purchaser and the supplier. The materialshould accompany with Materials Supply DataSheet ( MSDS ).

4.2 Marking

The packages shall be securely closed and legiblymarked with the following information:

a) Name of the material,

b) Indication of source of manufacture,

c) Net mass of the material,

d) Lot/Batch reference number, and

e) Handling and storage precautions ( if any ).

4.2.1 BIS Certification Marking

The packages may also be marked with the StandardMark.

4.2.1.1 The use of the Standard Mark is governedby the provisions of the Bureau ofZndian Standards

Act, 1986 and the Rules and Regulations madethereunder. The details of conditions under whichthe licence for the use of Standard Mark maybe grantedto manufacturers or producers maybe obtained fromthe Bureau of Indian Standards.

IS 6918:2002

Table 1 Chemical Requirements of Mercaptobenzothiazole ( MBT )

( Clause 3.2)

S1 No. Characteristic Requirement Method of Test,Ref to Annex

(3) (4)(1)

O

(2)

BAssay ( MBT content ), percent by mass, Min:

a) Powder — non coated grade

b) Powder — coated grade

c) Pellet

98.0

96.0

96.0

I70

176-184

0.05

cii) Melting point, “C:

a) Appearance of first droplet, &fin

b) Completion of melting

Residue on 150 micron IS Sieve, percent by mass,Max ( for powders only )

Diii)

Div) Residue on 63 micron 1S Sieve, percent by mass,Max (for powders only)

0.75

Loss on heating for 2 h at 105”C, percent bymass, Max

0.40 Ev)

F

G

H

J

vi)

vii)

viii)

ix)

Sulphated ash, percent by mass, Max 0.4

20

40

2.2

Copper content, ppm, Max

Manganese content, ppm, Max

Surface coating ( for coated grade only ) percentby mass, Max

5 SAMPLING conducted on individual sample.

5.1 The representative samples of the material shallbe drawn as prescribed in Annex L.

5.2 Number of Tests 5.2.2 Test for all other characteristics shall be conducted

5.2.1 Test for copper content ( see Table 1 ) shall be on a composite sample.

ANNEX A

( Clause 3.2)

MERCAPTOBENZOTHIAZOLE ( MBT )

A-1 QUALITY OF REAGENTS NOTE — ‘Pure chemicals’ shall mean chemicals thatdo not contain impurities which affect the results of

Unless specified otherwise, pure chemicals and distilled test or analysis.water ( see IS 1070 ) shall be employed in tests.

IS 6918:2002

ANNEX B

[ Table 1, S1 No. (i) ]

DETERMINATION OF ASSAY ( MBT CONTENT )

B-1 GENERAL

For routine work the method given below may befollowed while for more accurate work methodsbased on High Performance Liquid Chromatographydescribed in other overseas standards ( for exampleASTM D 5297-95) can be used.

B-2 ROUTINE METHOD

This method determines mercaptobenzothiazole( MBT ) as a major constituent in commercial products,in solutions or in blends that do not contain otherconstituents capable of reacting with iodine.

B-3 REAGENTS

B-3.1 Chloroform, LR Grade

B-3.2 Buffer Solution, pH 4.95

Dissolve 280 g of anhydrous sodium acetate and280 g ( 267-ml ) of glacial acetic acid in water and diluteto 1000-ml.

B-3.3 Iodine

0.10 N, standard volumetric solution.

B-3.4 Starch Indicator Solution ( freshly prepared)

B-4 PROCEDURE

Weigh to the nearest 0.1 mg, 0.50+ 0.05 g of the wellmixed sample and transfer to a 500-ml dry conicalflask (in case of pelleted products, crush a 50 g ofrepresentative sample, mix well and use0.50 + 0.05 g for the test ). Add 50-ml chloroformsolvent and dissolve the sample. Add 200 ml waterand 25-ml buffer solutionpH 4.95. Add 0.5-ml of starchindicator solution and titrate against 0.10 N standardiodine solution shaking the flask vigorously duringthe titration until a permanent blue colour appears.Carry out a blank ofrepeating steps 2 to 4 in the absenceof the sample.

B-5 CALCULATION

Assay ( MBT content),

(V1-VZ)XI.672percent by mass =

M

where

v, =

V* =

M.

ml of 0.1 N iodine solution used by thesample;

ml of 0.1 N iodine solution used for theblank titration; and

mass of the sample taken in g.

ANNEX C

[ Table 1, S1No. (ii)]

DETERMINATION OF MELTING POINT

C-1 GENERAL METHOD

Essentially it is a capillary tube method, though themedium for heating can be the traditional liquidwith a stirrer or a solid metal block, heated by gas orelectricity.

C-1.1 Apparatus

C-1.1.1 Melting Point Tubes

Glass capillary tubes approximately 10 cm long withwall thickness 0,1 to 0.15 mm, and internal diameter0.1 to 1,1 mm, closed at one end.

C-1.1.2 Thermometer

The thermometer shall be calibrated and graduatedin 1“C divisions. During the determination thethermometer shall be immersed to the depth at which

it was calibrated.

C-1. 1.3 Heating Medium

The liquid bath apparatus is shown in Fig. 1. It consistsof a 500-ml borosilicate glass beaker ( tall form) closedwith a chloroprene rubber bung through which passesa central outer glass tube. The outer tube is fittedwith a chloroprene rubber bung and a stirrer on a shaftpassing through inner tube. Outer tube has a ring offour holes blown in it to allow circulation of the heatingliquid. The chloroprene rubber bung is bored with ahole to hold the thermometer and small holes on eitherside of this for the melting point tubes. A metal screenis necessary to protect the apparatus from drought.The heat transfer fluid should be such that it is notvolatile below 300°C, is colorless at workingtemperatures, non-flammable and does not attack the

3

IS 6918:2002

THERMOMETER

SECTION XX

/’”- ‘“BE

Lx

,--- RUBBERBUNG

FOUR HOLES

.1x

/-’-’-GIASSBEAKER

FIG. 1 APPARATUS FOR DETERMINATION OF MELTING POINT

rubber bung. Asilicon oilofsuitable low viscosityis suggested. Alternatively anelectrically (or gas)

heated metal block may be used as the heating medium.It is important that the rate of heating of the blockshall be readily controlled.

C-1.2 Procedure

Transfer a small quantity of the finely ground sampleto each of the capillary tube and cause it to fall to thecIosed end by tapping on the bench. The quantityused should fill 2.5 to 3.5 mm depth of the tube whencompacted. Heat the block ( or bath with the stirrerin continuous operation ) rapidly to 20 to 25°C belowthe lower end of the expected melting range and thenadjust the rate of heating so that the temperature risesuniformly at a rate of 1OC/min. When thetemperature is about 12°C below the lower end of thespecified melting range, the capillaries are insertedinto the holes in the metal block ( or inserted throughthe small holes in bung B and held at the desiredimmersion level by sticking a small paper flag Karoundeach one ).

C-1.3 Report

Continuously observe the sample as the temperaturerises and record the temperatures when there is:

a) the first appearance of drops or a meniscus,and

b) complete melting.

C-2 REFEREE METHOD

C-2.1 Apparatus

C-2.1.1 Heating Bath and Screen

A round-bottomed 150-ml heat-resistant glass flaskhaving a neck about 100 mm long and 50 mm diameterfilled with pure concentrated sulphuric acid ( or anyother suitable liquid, such as glycerine or paraffinoil ) to about three-fourths of its capacity. A test tubeabout 150 mm long and of such diameter as to fit looselyin the neck of the flask is placed in position by glassbeads fused on it near the top so that the bottom ofthe tube is about 12.5 mm from the bottom of the flask.This tube is also filled with the same liquid, the levelof which should be slightly lower than that of the liquidin the flask. The tube is closed by a cork carrying ‘athermometer and provided with a slit on one side toallow the hot air to escape. A metal screen is necessaryto protect the flame and heating bath from draught.A suitable screen is made from sheet iron bent twiceat right angles, having a height of about 45 cm withsides and back about 20 cm in width and the frontopen. At a distance of 20 cm from the bottom there isa edge 12.5 mm side on the inside. A sheet of ironwith a central hole38 mm in diameter is placed on theedge and a sheet of asbestos with a central hole38 mm in diameter is placed on the top of the iron sheet.At the back of the screen, immediately behind the flaskwhen in position, there is a hole 38 mm in diameterbehind which a suitable source of illumination ( say,electric lamp ) is placed.

C-2.1.2 Melting Point Tubes

Readymade tubes ( 100 mm long and approximately1.5 mm external diameter) are recommended. Theseshall be sealed at both the ends as soon as they aretaken out from the package. Just before use, breakoff one end.

C-2.1.3 Thermometer

The thermometer used shall be standardized coveringthe approximate range, and graduated in 0.1 “Cdivisions. The bulb of the thermometer should beabout 6.35 mm long and 4.8 mm in diameter. Immersethe thermometer to the depth at which it has beenstandardized.

C-2.2 Procedure

C-2.2. 1 Preparation of TestSample

It is essential to ensure that a high degree of uniformityof the sample is attained on account of very smallamount of material taken for the test. Prepare thesample as follows:

Grind 2 to 5 g of the well-mixed sample in a small,clean, dry glazed porcelain or glass mortar, thengrind finely a portion of this in an agate mortar.

.-A---.

IS 6918:2002

C-2.2.2 Transfer a small quantity of the preparedmaterial to a capillary tube, and cause the portion takento fall to the sealed end by tapping on the bench.Assemble the apparatus with the thermometer in sucha way that the bottom of the bulb is not less than6.35 mm from the bottom of the test tube. Heat thebath rapidly to a few degrees above the expected meltingpoint, allow the temperature to fall gradually to about15°C below the expected melting point, then adjustthe rate of heating so that the temperature risesuniformly at the rate of 10C/min. When the temperatureis about 12°C below the expected melting point,withdraw the thermometer and quickly attach thecapillary tube to it, either by means of a thin rubberring ( cut from the end of a narrow rubber tubing ) orby causing it to adhere by capillary attraction. The

sealed end of the capillary tube must be on a levelwith the bottom of the bulb of the thermometer.Carefully replace the thermometer with the adheringcapillary tube in the inner tube. If this operation hasbeen carried out quickly, the material under test shallbe introduced into the heating bath ( the temperatureof which is rising uniformly at the rate of10C/min ) when the bath temperature is about10°C below the expected melting point.

C-2.3 Report

Record the temperature when thc;e is:

a) the first appearance of drops or of a meniscus,and

b) complete melting.

ANNEX D

[ Table 1, S1No. (iii) and(iv)]

RESIDUE ON (63 micron/150 micron)

D-1 APPARATUS

D-1.l Gailie-Porriti Sieve

The apparatus ( see Fig. 2 ) consists of a metal funnelterminating at the foot in a short cylindrical outlet,in which is inserted a shallow removable cup. To thebottom of the cup, a wire gauge ( conforming to 63/150 micron IS Sieve) of25 mm diameter is soldered.Water under pressure of 1.5 to 3.5 kgf/cm2 is suppliedby a tube fitted with a nozzle designed to dischargea spreading jet throughout the wire gauze. The tubeis also so arranged that the distance of the orifice inrelation to the wire gauze can be adjusted. The tubeis provided with a filter to ensure removal of any solidparticles from the water. A second tube which is alsoprovided with a filter is improvised to supply a gentlestream of water for wetting the powder and forsupplying more water to the funnel during the progressof test. The area of the wire gauze shall be sufficientlylarge to prevent undue loss of pressure head in thecase of first tube.

D-2 PROCEDURE

D-2.1 Weigh accurately about 50 + 1g of the material.Fill half of the funnel with water from the subsidiarysupply, then bring the central jet ( see Fig. 2 ) intooperation. Transfer the weighed meterial to the metalfunnel in the form of a slurry with a suitable wettingagent. Turn off the subsidiary supply and, if necessary,

SIEVE

adjust the height of the central jet so that the level ofwater in the funnel commences to fall. When the levelhas fallen within 50 mm of the sieve, turn on subsidiarysupply until the level is within COmm from the top ofthe funnel and maintain there until the liquid appearsclear and continue supply then for a further periodof 1 min. Turn off the subsidiary supply and allowthe level to fall again. When funnel is empty, turn offthe main jet and allow to drain. Remove the cup andexamine for any large soft agglomerates. If present,break up gently with the finger and replace the cupand wash with water from the subsidiary supply for2 min. Transfer the grit on the sieve to a watch glass,dry to 100”Cand weigh. The above operation is carriedout with removable cups provided with 63/1 50 micronprovided with IS Sieve and 300 micron IS sieve andthe grit on the sieve is dried and weighed, each timeseparately.

D-2.2 Powders which are very light, are difficult towet at onetime in as large quantity as 50 g. To facilitatewetting of these powders, either a small amount ofwetting agent may be added or the material shouldbe added in small quantities into the apparatus.

D-3 CALCULATION

Express the mass of residue as percentage of thematerial taken for the test and the IS Sieve used forthe test.

5

6,-

IS 6918:2002

KFILTERS

l\ /- WATER

WATE- CENTRAL

JET

4

h UNIONNUT

JET END VIEW I $rl+d

dL-REMoVABLE

BYuNSCREWING

WIRE GAUZE

uENLARGED VIEW AT A

FIG.2 GALLIE-PORRITISIEVE

ANNEX E

[ Tab/e 1, S1No. (v) ]

DETERMINATION OF LOSS ON HEATING AT 105”C

E-1 PROCEDURE dish to a desiccator and cool. Remove the dish and

Weigh accurately about 5 g of the material in a taredweigh.

flat-bottomed dish about 8 cm in diameter. Keep the E-2 CALCULATIONdish with the material in an oven maintained at105 + 2°C till a constant mass is reached ( normally Express the loss in mass as the percentage of thethis takes 2 h). At the end of this period, transfer the mass of the material for test.

ANNEX F

[ Table 1, S/ No, (vi) ]

DETERMINATION OF SULPHATED ASH

F-1 PROCEDURE fbrnace at 500°C for 1h. Cool in a desiccator and weigh.

.2. . . . .,

Weigh accurately about 5 g of the sample in a tared F-2 CALCULATIONsilica crucible. Heat with a low bunsen flame until allvolatile organic matter is removed and then heat more Sulphated ash,

strongly to remove carbon. Cool and moisten the Mass of the final residue x 100percent by mass =

residue with a drop of sulphuric acid and heat slowly Mass of the material takentill the acid fumes cease to escape. Heat in a muffle

6

IS 6918:2002

ANNEX G

[ Table 1, S1No. (vii) ]

DETERMINATION OF COPPER

G-O Both the methods using the Nessler cylinder andthe photoelectric absorptionmeter are given.

G-1 REAGENTS

G-1.1 Copper Solution

G-1.1.1 Dissolve 0.3928 g of pure recrystallizedcopper sulphate ( CuSO~.5H20 ) in 1 Iitre of distilledwater. One ml of the solution contains 0.0001 g ofcopper.

G-1.1.2 Dilute 25 ml of solution in A-7.1.1.1 toZ50-m[ with water in a measuring flask. One ml of thesolution contains 0.000 01 g of copper. Solutionin G-1.1.2 should be freshly prepared from solutionin G-1.1.1 as required.

G-1.2 Ammonia, Aqueous— R. D. 0.880.

G-1.3 Citric Acid, Aqueous

Dissolve 50 g of solid citric acid in 100-ml of distilledwater.

G-1.4 Dilute Hydrochloric and Nitric Acid Mixture

G-1.5 Sodium Sulphate — anhydrous.

G-1.6 Sodium Diethyl Dithiocarbamate Solution( SDC )

Dissolve 0.1 g of pure sodium diethyl dithiocarbamatein 100-ml distilled water; preserve the solution in anamber-coloured bottle.

G-1.7 Zinc Diethyl Dithiocarbamate ( ZDC )Reagent

Dissolve 1 g of.sodium diethyl dithiocarbamate inwater and add 2 g of zinc sulphate ( ZnS01.7H20 ),Extract the resulting zinc diethyl dithiocarbamate byshaking with 100-ml of chloroform. Separate thechloroform solution and dilute to 1 Iitre withchloroform. Store in amber coloured bottle. Underthese conditions the solution is stable for at leastsix months.

G-2 PROCEDURE

G-2.1 Nessler Cylinder Method

G-2. 1.1 Weigh accurately 5 g of prepared sample tothe nearest mi1Iigram into silica dish, heat with a lowbunsen flame until all volatile organic matter isremoved and then heat more strongly to remove carbon.Copper wiIIbe lost if temperature of the dish exceeds550”C for any length of time. For most accurate work,

ash in a muffle furnace at a temperature notexceeding 500°C.

G-2. 1.2 Dissolve the ash in 10-ml hydrochoric-nitricacid mixture, and add 40-ml of water. Make slightlyalkaline with ammonium hydroxide, add 3-ml ofconcentrated ammonium hydroxide and boil. Filterthrough a filter paper Whatman No.44 and wash wellwith water. Dilute the combined filtrate and washingsto 100-ml in a measuring flask ( Sample Solution A ).

G-2.1.3 Take 50-ml of the Sample Solution A in a100-ml Nessler cylinder, dilute to about 90-ml withwater, add 1 ml of a 5-percent aqueous solution ofgum arabic, neutralize with ammonium hydroxidesolution and add 2-ml in excess and make up to themark with water. Call this as Sample Solution.

G-2.1.4 At the same time prepare a series of standardcomparison solutions by diluting 1,2,3,4 and 5 ml ofthe copper solution ( see G-1.l.2 ) separately to about90-ml in a 100-ml Nessler cylinder, add to each of thesolution 2-ml of ammonium hydroxide solution and1-ml of a 5-percent aqueous solution of gum arabicand make up to the mark with water. Call these asStandard Solutions. To each of these solutions( Standards and Sample ) add 2-ml of the sodiumdiethyl dithiocarbamate solution, mix thoroughly andcompare the colour of Sample Solution with those ofthe Standard solutions ( colour with 1-ml coppersolution corresponds to 4 ppm and with 5-ml 20 ppmof copper).

G-2. 1.5 For very accurate work the test may berepeated, comparing against a narrower range ofStandard Solutions graded in 0.5-ml.

G-2.2 Photoelectric Absorptionmeter Method

G-2.2.1 Take the crucible containing the ash( see G-2.1.1), cool, moisten within 0.5-ml to l.O-mlof water and cover with a watch glass. As blank, treatsimilarly a clean, empty and ignited crucible. Add10-ml of dilute hydrochloric-nitric acid mixture to thecrucible and digest the mixture on a steam-bath forabout 20 to 30 min. Wash the contents of the crucibleinto a small beaker or flask. Add 5-ml of the citricacid solution, followed by dropwise additions ofammonia until the solution is just alkaline to litmuspaper. Cool the solution and transfer to a separatingfunnel. Add 2-ml of ammonia and dilute to about40-ml with water.

G-2.2.2 Pipette 25 ml of ZDC reagent into the solutionand thoroughly shake for 2 min. After allowing

.,...-.

‘{

7

IS 6918:2002

sufficient time for separation, drain outthe chloroformlayer into a dry stoppered flask containing aboutO.lgofanhydrous sodium sulphate. If turbidity existsafter standing for about 30 rein, make further smalladditions of anhydrous sodium sulphate until thesolution becomes clear.

G-2.2.3 Decant the solution through a plug of glasswool or filterpaper intoa 2 cm cell of the absorptionmeterand measure the optical density at approximately435 nm or using a violet filter.

G-2.2.4 Carry out a blank determination on the reagentsused and from the corrected value for the optical density,obtain the concentration of copper in the test solution

from the calibration curve prepared earlier.

G-2.2.5 For drawing calibration curve prepare a seriesof standard solutio~s using 0.5, 1.0, ‘2.0, 3.0 and soon up to 10.O-ml of standard copper solution. Add5-mI of citric acid solution and 2-ml excess of ammoniato each. Dilute each solution to 40-ml and extract thecopper with 2-ml ZDC solution as described above.Measure the optical density of the solutions usingZDC reagent as reference. Plot a graph showing therelationship between optical density and microgramsof copper. Check the calibration graph as necessary,depending on the type of instrument used and on localconditions.

ANNEX H

[ Table 1, SINO. (viii) ]

DETERMINATION OF MANGANESE

H-O Both the methods using the Nessler cylinder andphotoelectric absorptionmeter are given.

H-1 REAGENTS

H-1.1 Potassium Bisulphate — fused.

H-1.2 Potassium Periodate

H-1.3 Phosphoric Acid — 1:1 ( v/v)

H-1.4 Sulphuric Acid — concentrated and1:1 (v/v)

H-1.5 Standard Manganese Solutions

H-1.5.1 Measure 45.5-ml of 0.1 N potassiumpermanganate solution into a 250-ml beaker.

Alternatively, dissolve 0.144 g of potassiumpermanganate crystals in about 50-ml of water. Toeither of the above solutions and 5-ml of sulphur acid( I :1 ) and then a saturated solution of suiphur dioxidein water, about 1-ml at a time, until the solution isjustdisco lourized. Dilute to about 1so-m] with water and

boil gently for 15 min. Cool, transfer the solution toa 500-ml measuring flask and dilute to the mark withwater and mix well. One ml of the solution contains0.000 I g of manganese.

H-1.5.2 Measure 100.O-ml of solution from H-1.5.1into a 500-ml measuring flask, dilute to the mark withwater and mix well. One ml of the solution contains0.00002 g of manganese ( Mn ). Solution in H-1.5.2should be freshly prepared from solution in H-1.5.1.

H-2 PROCEDURE

H-2. 1 Nessler Tube Method

H-2. 1.1 Weigh accurately 5 g of the prepared sample

to the nearest milligram in a silica crucible of about25-ml capacity (4 cm dia x 3 cm deep ). Support on asilica triangle and heat with a small bunsen flame untilall the volatile or readily combustible matter areremoved. Then heat more strongly until most of thecarbon has been removed. Completely remove anysooty deposit from the upper half of the crucible byigniting with a fairly strong bunsen flame directed atright angles to the wall of the crucible, but avoid strongdirect heating of the main residue in the bottom ofthe crucible. Allow to cool, add a little concentratedsulphuric acid dropwise round the walls of the crucible,in amounts just suftlcient to moisten the carbonaceousresidue. Carefully heat the crucible so that copiousevolution of sulphur trioxide fhmes occurs, repeatingthe process until all organic matter is destroyed anda clean ash remains. Finally moisten with a littlesulphuric acid until the acid is driven off and fumingceases, and then heat more strongly a few minuteslonger. Again moisten with a little sulphuric acid andgently ignite until evolution of fumes almost but notquite ceases. Avoid strong, ignition, in order to retainthe ash as far as possible in the form of sulphate.

H-2. 1.2 Add 5 g of fused potassium bisulphate andfuse cautiously at first, gradually increasing thetemperature to a moderate red heat. Heat until a clearmelt is obtained or until no further action on the ashoccurs and allow to cool. Add 2-ml of sulphuric acid( 1:1 ) and 15-ml water to the contents of the crucibleand heat until the cake dissolves or is completelyloosened from the walls of the crucible. Completelytransfer the contents of the crucible to a 100-ml beakerand heat until all soluble matter has dissolved. Filter

8

,/+

IS 6918:2002

into a 100-mlconical flask and wash with a little water,diluting to 40-ml. Add 4-ml of phosphoric acid, mixand add 0.3 g potassium periodate. Boil gently for5 min and keep hot at about 90°C on a hot plate fora further 30 min. This is necessary to ensure fulldevelopment of the permanganate colour. Cool, makeup to 50-ml and mix well ( test solution).

H-2.1.3 Carry out a reagent blank determinationalongside the test, using the same quantities of reagents,but omitting the sample.

H-2.1.4 Measure 1.0,2 .0,3.0,4.0 and S.O-mlof standardmanganese solution ( see H-1.5.2) into 100-ml conicalflasks, dilute each to 40-ml, add 2-ml sulphuric acid

( 1:1 ), 4-ml phosphoric acid, mix and add 0.3 g ofpotassium periodate. Boil gently for 5 min and continueheating at about 90”C on a hot plate for a further30 min. Cool, makeup to 50-ml and mix well. Comparethe colours of the reagent blank and test solutionswith those of the standards, in the usual manner andhence estimate the amount of manganese present.One ml of the standard solution corresponds to 4 ppmof manganese in the sample.

H-2.1.5 For very accurate work the test maybe repeated,comparing against a narrower range of standardsgraded in 0.5-ml.

H-2.2 Photoelectric Absorptionmeter Method

H-2.2.1 Rinse out the optical cells with dilute potassiumpermanganate, then with stabilized water and finallywith the test solution. Measure the optical densityof the test solution ( see H-2.1.2) against the reagentblank solution as reference solution by means of aphotoelectric absorptionmeter using Yellow green 605filter ( for a spectrophotometer set at a wavelengthof 525 nm ) and cells of 4 cm optical length. From theobserved optical density and the calibration graphof the instrument, obtain the concentration of themanganese in the test solution. Report the manganesecontent as the nearest whole number of manganesein parts per million of sample.

H-2.2.2 For drawing calibration curve add 0.5, 1.0,2.0, 3.0, 4.0 and 5.O-ml of the standard manganesesolution ( containing 20 mg of manganese per ml )to 5.O-ml of sulphuric acid ( 1 : 1 ) contained in a100-ml conical flask and dilute to 25 to 30-ml withstabilized water. Add 4-ml of phosphoric acid, mixwell, add 0.3 g of potassium periodate and continueas described for the test solution. Determine the opticaldensity of the solutions containing no addedmanganese as reference solution with a yellow green605 filter (or a spectrophotometer set at a wavelengthof 525 nm ). Plot the relationship between the massof manganese in micrograms and the optical density.

ANNEX J

[ Table 1, S1 No. (ix) ]

DETERMINATION OF SURFACE COATING AGENT

J-1 OUTLINE OF THE METHOD

In this method, the accelerator sample is washed withpetroleum ether and filtered. The filtrate of petroleumether is evaporated to dryness over water bath. Thecontent of petroleum ether soluble matter is taken asthe content of surface coating agent.

J-2 REAGENT

J-2,1 Petroleum Ether — boiling range 40 to 60°C.

J-3 PROCEDURE

About 5 g sample of the accelerator is accuratelyweighed ( M ) to nearest 0.1 mg inan 100-mlErlenmeyerflask, 25-ml of petroleum ether is added to the flaskby means of a measuring cylinder. The contents ofthe flask are stirred thoroughly for 5 min. The contentsare then filtered through a Gooch crucible( Type G4 ). The contents of the flask and the residue

in the crucible are washed twice each time taking25-ml of petroleum ether. The filtrate and the washingsare transferred to a previously weighed ( Ml ) accurateto nearest 0.1 mg evaporating dish. The petroleumether is evaporated off over a water bath till a constantweight ( Mz ) is reached.

J-4 CALCULATION

Surface coating agent,M2-til X 100

percent by mass =M

mass in g of the evaporating dish,

mass ing of the evaporated dish and residue,and

mass in g of the sample taken.

1S 6918:2002

METHOD FOR COMPOUNDING

K-1 TEST METHOD

ANNEX K

( Clause 3.3)

AND TESTING OF MERCAPTOBENZOTHIAZOLE

For guidance, the test compound with the followingcomposition may be used for testing performanceproperties of mercaptobenzothiazole in rubbercompounds:

Item Parts by Mass

Natural Rubber, Grade A 100( conforming to IS 4588 )

Zinc Oxide 5( conforming to IS 3399 )

Stearic Acid 1( conforming to IS 1675)

BIanc Fix ( Barium Sulphate ) 75( conforming to IS 1683 )

Sulphur 2.5

MBT Sample 0.5

K-2 PROCEDURE

K-2.1 Follow the procedure prescribed inIS 3660( Part 8 ).

K-3 TESTS

K-3.1 The tests given below are recommended foreach test sample. The approved sample shall also betested side by side using the same constituents asprescribed in K-1 but with the exception of sulphurand accelerator.

K-3.1.1 Mooney Scorch at 120°C in accordance withthe method prescribed in IS 3660 ( Part 7 ).

K-3.1.2 Tensile strength, modulus at 300 percentelongation, elongation at break at different cures 20,30 and 40 min at 141“C ( from below to above theexpected optimum cure ), in accordance with the methodprescribed in IS 3400 ( Part 1 ).

K-3. 1.3 Hardness on optimum cure at 141“C inaccordance with the method prescribed inIS 3400( Part 2 ).

K-4 RESULTS

K-4.1 The values obtained with the test sample shouldnot vary by more than 20 percent for Mooney scorchand + 10 percent for all the other characteristics fromthose obtained with the approved sample.

ANNEX L

( Clause 5.1)

SAMPLING OF MERCAPTOBENZOTHIAZOLE

L-1 GENERAL REQUIREMENTS OF SAMPLJNG

L-1.1 In drawing, preparing, storing and handlingtest samples, the following precautions and directionsshall be observed.

L-1.2 Samples shall be taken in a protected place notexposed to damp air, dust or soot.

L-1.3 The sampling instrument shall be clean anddry when used.

L-1.4 The samples, the sampling instrument and thecontainer for samples shall be protected fromadventitious contamination,

L-1.5 To draw a representative sample, the contentsof each container selected for sampling shall be mixedas thoroughly as possible by suitable means.

L-1.6 The samples shall be placed in clean, dry and

air-tight glass or other suitable containers, on whichthe material has no action.

L-1.7 The sample containers shall be of such a sizethat they are almost completely filled by the sample.

L-1.8 Each sample container shall be sealed air-tightafier filling and marked with the full details of sampling,the date of sampling and the year of manufacture ofthe material.

L-1.9 Samples shall be stored in such a manner thatthe temperature of the material does not vary undulyfrom the normal temperature.

L-2 SCALE OF SAMPLING

L-2.1 Lot

All the containers in a single consignment of the materialdrawn from a single batch of manufacture shall

10

IS 6918:2002

constitute a lot. Ifaconsignment isdeclared to consistof different batches of manufacture, the batches shallbe marked separately and the groups of containersin each batch shall constitute separate lots.

L-2.2 Thenumber ofcontainers to deselected fromthelotshall depend uponthe sizeofthe lot. Ifthe lotconsists of 50 or less containers, 2 out of them shallbe selected at random and for higher lot sizes3 containers shall be selected.

L-2.3 These containers shall deselected at randomfrom the lot and in order to ensure randomness, theprocedure given in L-2.3.l n,aybe adopted.

L-2.3.1 Arrange all the containers in the lot in asystematic manner and starting from any containercount them asl, 2,3 ....... up to r, r being the integralpart ofN/n, where N is the lot size, and n is the numberof containers to be selected ( 2 or 3 as the case maybe ). Every rth container thus counted shall bewithdrawn. All such containers shall constitute thesample.

L-3 TEST SAMPLES AND REFEREE SAMPLES

L-3. 1 Draw with an appropriate sampling instrumentsmall portions of the material from different parts ofthe container selected from the lot ( see L-2.2 ). Thetotal quantity of the material so drawn should besufficient to conduct the tests for all the requirements.

L-3.2 Mix thoroughly the portions drawn from thesame container to form an individual samplerepresentative of the container. In addition, mix togetherequal portions from the individual samples to form acomposite sample representative of the lot.

L-3.3 Divide all the individual samples ( see L-3.1)and the composite sample (see L-3.2 ) into three equalparts forming three sets of test samples. Transfer thesetest samples immediately to thoroughly dried samplecontainers which shall then be sealed air tight.Label them with all the particulars of sampling givenunder L-1 .8. Send one of these sets to the purchaserand one to the supplier.

L-3.4 Referee Samples

The third set of test samples, bearing the seals of thepurchaser and the supplier, shall constitute the refereesamples to be used in case of dispute between thepurchaser and the supplier. It shall be kept at a placeas agreed to between the purchaser and the supplier.

L-4 NUMBER OF TESTS

L-4. 1 Tests for characteristics given in Table 1 shallbe conducted for each of the individual samples inthe set of test samples.

L-4. 1.1 Test for compounding ( see 3.3 ) may beconducted on the composite sample in the set of testsamples.

L-5 CRITERIA FOR CONFORMITY

L-5. 1 The lot shall be declared as conforming tothis specification if the requirements of L-5.1.1and L-5.1.2 are satisfied.

L-5.1.1 The individual sample when tested forvarious characteristics shall satisfy the relevantrequirements as given in Table 1.

L-5. 1.2 For compounding test the compositesample shall meet the specified requirements givenin Annex K.

11

IS 6918:2002

ANNEX M

( Foreword)

COMMITTEE COMPOSITION

Rubber Products Sectional Committee, PCD 13

Organization

Apar Industries Ltd, Mumbai

All India Rubber Industries Association, Mumbai

Attuned Polymers Pvt Ltd, Mumbai

Bayer India Ltd, Mumbai

Bengal Waterproof Ltd, Kolkata

Dunlop India Ltd, Kolkata

Directorate General of Supplies and Disposals, New Delhi

Escon Consultants Pvt Ltd, Kolkata

Hindustan Latex Ltd, Thiruvanathapuram

ICI India Ltd, Kolkata

Indian Petrochemicals Corporation Ltd, Baroda

Indian Rubber Mfrs Research Association, Thane

J .K. Industries Ltd, Rajasthan

Ministry of Deferice ( DGQA ), New Delhi

Ministry of Foreign Trade, Kolkata

Modi Rubber Ltd, Meerut ( U, P. )

MRF Ltd, Chennai

National Test House, Kolkata

National Organic Chemicals Industries Ltd, Thane

Philips Carbon Black Ltd, Distt Bharuch

Phoenix Yule and Co Ltd, Kolkata

Representative(s)

SHRI MANU M. PATEL ( Chuirntan )

SHRI M. M. PATEL

SHR~K. D. SHAH ( Alternate )

!kt MEHUL PATEL

Stim RA~ENDRA INaAWALE ( Alternate )

SHRI P. K. CHATTERIEE

THE MANAGER (TECH SERVICE) ( Alternate )

SHRI B. BANERJEE

SHRt A. K. BANDOPADHYAY

SHRI S. K. NANDI ( Alternate )

SHRI SUNDER LAL

SHRI A. K. JAIN ( Alternate )

DR D. BANERJEE

SHRI S. R. PANICKER

SHRt J. SAHAYADASAN( Alternate )

SHRI M. K. CHAITERJEE

SHRI A. K. BASU

SHRI R. K. GARG ( Alternate )

DR W. MILLINS

DR M. S. BANERJEE( Alternate )

DR R. MUKHOPADHYAY

SHRI V. K. MISRA ( Alternate )

SHRI A. K. BANDHOPADHYAY

SHRI GAUTAM GUPTA (Alternate)

SHRI K. J. SRIVASTAVA

SHRI P. P. SAXENA ( Alternate )

SHRI MARKAND MrfTAL

SHRI S. K. SHARMA ( Alternate )

SHRI ZACHARIAH GEORGE

SHR[ A. GEORGE JOHN ( Alternate )

SHRI D. N. ROY

SHRt A. K. CHAKRABORTY ( Alternate )

SHRI C. S. INAMDAR

SHRI D. S. DESAI ( Alternate )

DR B. BANERJEE

DR S. CHAKRABORTY ( Alternate )

SHRI T. K. MUKHERJEE

DR A. GUHA ( Alternate )

i

( Continued on page 13 )

12

I

IS 6918:2002

( Continuedfrom page 12 )

Organization

RAEI Polymers, Kolkata

Research, Designs and Standards Organization, Lucknow

Rubber Research Institute of India, Kottayam

Sundaram Indusries Ltd, Madurai

Synthetics and Chemicals Ltd, Mumbai

Swastik Rubber Products, Pune

Tyre Corporation of India Ltd, Kolkata

BIS Directorate General

Representative(s)

SHRI B. DUTTA

DR S. P. MANIK

THE ASSISTANT INSPECTIONENGINEER

( Alternate )

SHRI K. S. GOPALAKRISHNAN

DR M. G. KUMARAN ( Alternate )

SHRI R. RAMAN

SHRI C. GOPINATHAN( Alternate )

DR R. N. MEHROTRA

DR VED PARKASH ( Alternate )

SHRI A. V. KATE

SHRI B. N. BHAITACHARYYA

DR SUNIL KUMAR GHOSH( Alternate )

ANJANKAR,Director& Head ( PCD )[RepresentingDirectorGeneral(Ec-oficioh4ember) ]

J4ernber Secretary

SHRIR. P. MJSHRA

Joint Director (pCD), BIS

Rubber Chemicals and Compounding Ingredients Subcommittee, PCD 13:5

Philips Carbon Black Ltd, Distt Bharuch DR B. BANERIEE( Convener )SHR1ARUP MUKERJEE( Alternate )

Apar Industries Ltd, Mumbai DR PRABHU

SHRI S. C. MAiTY ( Alternate )

Bata India Ltd, Kolkata SHRI DIPANKERBANERJEE

SHRI S. M. MtTRA ( Alternare )

Bayer ( India ) Ltd, Mumbai DR D. J. BHARUCHA

SHRI P. K. CHATTERIEE( Alternate )

Cabot India Ltd, Mumbai SHRI P. M. JACOB

Dunlop India Ltd, Kolkata SHRI D. P. SJNHA

DR A. GUHA ( Alternate )

Hindustan Latex Ltd, Thiruvanathapuram SHR1 S. R. PANICKER

SHRi J. SAHAYADASAN( Alternate )

Hi-Tech Carbon, New Delhi DR DINESH CHANDRA GOEL

SHRI ONKAR SJNGHBHANDARJ ( Alternate )

ICI Ltd. Chemical Division, Hoogly DR S. CHAKRABORTY

SHRJJ. K. BHATTACHARJEE( Alternate )

J. K. Industries, New Delhi DR R. MUKHOPADHYAY

DR A. S. DEURI ( Alternate )

Modi Rubber Ltd, Modipuram SHRI G. C. UPPADHYAY

MRF Ltd, Chennai SHRI A. GEORGE JOHN

SHRI ZACHARtAH GEORGE ( Alternate )

National Organic Chemicals Industries Ltd, Thane SHRI C. S. INAMDAR

SHRI D. S. DESAI ( Alternate )

( Continued on page 14 )

13

1S6918:2002

( Continued jirom page 13 )

Organization

Phoenix Yule and Co Ltd, Kolkata

The Rubber Board, Kottayam

Rubber Products Ltd, Thane

Synthetics and Chemicals Ltd, Mumbai

Swastik Rubber Products Ltd, Pune

Tyre Corporation of India Ltd, Kolkata

Representative(s)

SHRI T. K. MUKHERJEE

DR A. GUHA ( Alternate )

SHR1 K. S. GOPAt.AKRISHNAN

SHW N. R. PEETHAMBARAN( Alternate )

SHRi LAXMAN K. SHEITY

DR R. N. MEHROTRA

DR VEtI PRAKASH

SHRI A. V. KATE

SHRI B. N. BHATTACHARYA

DR S. K. GHOSH ( Alternate )

1

14

Bureau of Indian Standards

BIS is a statutory institution established under the Bureau of Indian Standards Act, 1986 to promoteharmonious development of the activities of standardization, marking and quality certification of goods andattending to connected matters in the country.

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Review of Indian Standards

Amendments are issued to standards as the need arises on the basis of comments. Standards are also reviewedperiodically; a standard along with amendments is reaffirmed when such review indicates that no changes areneeded; if the review indicates that changes are needed, it is taken up for revision. Users of Indian Standardsshould ascertain that they are in possession of the latest amendments or edition by referring to the latest issueof ‘BIS Catalogue’ and ‘Standards : Monthly Additions’.

This lndian Standard has been developed from Doc : No, PCD 13( 1900).

Amendments Issued Since Publication

Amend No. Date of Issue Text Affected

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