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है”ह”ह

IS 3400-17 (1974): Methods of Test for Vulcanized Rubbers,Part XVII: Tear Strength - Angular Test Piece [PCD 13:Rubber and Rubber Products]

fS:34OO(PartXVII)-1974 ’

Indian Standard METHODS OF TEST FOR VULCANIZED RUBBERS

PART XVII TEAR STRiNGTH-ANGULAR TEST PIECE

( Second Reprint MAY 1988)

UDC 678.43:620.176.245

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

NEW DELHI 110002

Gr2 December 1974

IS : 3400 ( Part XVII ) - 1974

Indian Standard METHODS OF TEST FOR L VULCANIZED RUBBERS

PART XVII TEAR STRENGTH -ANGULAR TEST PIECE

Rubber Products Sectional Committee, CDC 6

chailman RcpreSCNf itq DR D. BANERJ~G &con Consultants Pvt Ltd, Calcutta

MambCTZ

SHRI A. T. BASAK Directorate Gcncral of Supplies & Disposals, New Delhi

SHRl s. K. Bose National Test House, Calcutta SHRI A. GHOSH (Alfmnte )

SHRI D. K. CIIATTERJEE Alkali Sr Chemical Corporation of India Ltd, Calcutta DR S. K. RAY ( Alfmatc )

SHRI S. S. CHOPRA Export Inspection Council of India, Calcutta SHRI K. M. BIJI.I ( Alfernafe )

SHRI S. L. GANDHI Ministry of Defcnce ( R & D ) SHRI M. G. BHAR~AVA ( A~fcrt~fc )

SWRI G. <:. jA1N Hindustan Steel Ltd, Ranchi SHRI 0. i%. KOIILI Railway Board SHR~ M. KUU.\RAN Ministry of Dcfence ( DC1 j SHRI LALIT MOH.AY .JAMNADAS Cosmos India Rubber Works Pvt Ltd, Bombay

SHR~ PuI.I:; 1.. hwARlWALA ( ~&ernate ) SHRI s. v. L,%I.i!l:\ Lathia Rubber Manufacturing Co Pvt Ltd, Bombay

SHRI D. P. L.?x 1::~ ( Alfcrnnfe ) Smr S. K. MATTHAN Madras Rubber Factory Ltd, Madras

SHRT K. J. ABRAHAM (Alfenzafe ) DR K. N. MODAK All India Rubber Industries Association, Bombay

SHRI K. R. SENGUPTA ( Alfernofe ) SHRI S. MUKHERJEE Dunlop India Ltd, Calcutta

SHRI P. N. S. MYER ( Alfemfc ) DR C. K. N. NAIR Rubber Board, Kottayam SHRI S. C. NANDY Bata India Ltd, Calcutta SHR~ R. R. PANDTT Bayer ( India ) Ltd, Bombay .%fRl ht. M. PA-I-EL Synthetics & Chemicals Ltd, Bombay SHRI K. RAJQOPAUL Indian Oil Gorporation Ltd, Bombay DR N. V. C. RAO Directorate General of Technical Development, New

Delhi SHRI G. R. INAMDAR ( Alternate )

@ Copyrichf 1974

BUREAU OF INDIAN STANDARDS

This publication is protected under the I&an Copyright Acr (XIV of I.957 ) and

reproduction in whole or in part by any means except with written permission of the publisher shall be deemed to be an infringemenr of copyright under the said Act.

lumbers itl?pfesenfing

Sxmr B. ROY National Rubber Manufacturcn Ltd, Calcutta SHar AmTAmih SEN ( Aknlab )

thR~ R. c. SYBD Indian Rubber Manufacturers’ Research Association, Bombay

SHru s. K. GHosH ( Altu?&Yh) SHRI D. D. TALWALKAR All India Automobile & Ancillary Industries As&a-

tion, Bombay Swnr K. M. KHALADKAR (Akin&)

&XXI D. D.u GUPTA, Director General, BIS ( &e&k Mkabfl ) Deputy Director General

*clorv SHRI SATQH CHANIJ~R

Deputy Director ( Cbem ), BlS

Methods of Testing Vulcanized Rubbers Subcommittee, CDC 6 : 9

C-r

SHRl M. M. PATJJL

M#l?lbtTS

Synt&ia Et Chemicals Ltd, Bombay

SHRI N. M. RXGE ( Alfmrat~ to Shrl M. M. Pate1 )

Ssm1 S. K. Boss National Test House, Calcutta SHRI A. GHOSH ( Ahmate )

DR S. N. CAUCRAVARN Bayer ( India ) Ltd, Bombay DR S. K. BH~TNAGAR (Al&ma& )

SHRI D. K. CI~ATI-YIRJEE Alkali & Chemical Corporation of India Ltd, Calcutta SHRI K. R. SESHADRI (AI&mate )

Ssxm B. H. DALAL Cknmos India Rubber Works Pvt Ltd, Bombay SHR~ PIJLZN L. K~NARIWALA ( Akmak )

SHRI S. B. GANGULY SHRI A. MIJ%H~x@~ ( Al(rmok )

Dunlop India Ltd, Calcutta

SHRI A. GEORGE JOHN Madras Rubber Factory Ltd, Madras SHRI G. R. SANRARANARAYANAN ( AIfcmafe )

Smt~ R. K. GWFA Ministry of Defence ( DGI ) SHRI G. R. KA~SHWAR Indian Rubber Regenerating Co Ltd, Bombay

SHRI A. R. -AK ( Ahtab ) DR S. P. MANIK Railway Board

SHRI G. DORAISWAYY ( Alemarc ) DR C. K. N. NAIR Rubber Board, Kottayam SHRI V. D. PANDSE Swastik Rubber Products Ltd, Poona

SHRI S. V. TA~I~AWADKAR ( Alternate ) SHRI V. R. RAO Sundaram Industries Pvt Ltd, Madural

SHRI K. c. ~HMUDI&WIAN (Akm& ) SHRI B. ROY National Rubber Manutketurers Ltd, Calcutta

SHRI J. CHA~TERJEE ( Alkmafu ) !&RI S. SARKAR Bata India Ltd, Calcutta

SHRX S. ROY ( Alkmak ) SHRI A. K. SBN CHAUDHURI Escon Consultants Pvt Ltd, Calcutta DR N. H. SIVARAXAKRI~HNAN Hindustan Latex Ltd, Trivandrum SHRI M. SALIM VOHRA

Swru A. D’XXJ~TA ( Altsmatr ) Premier Rubber & Cable Industries, Bombay

2

ISt34oo(PartXvIl)-1974

Indian Standard METHODS OF TEST FOR VULCANIZED RUBBERS

PART XVII TEAR STRENGTH-ANGULAR TEST PIECE

0. FOREWORD

0.1 This Indian Standard ( Part XVII ) was adopted by the Indian Standards Institution on 10 March 1974, after the draft finalized by the Rubber Products Sectional Committee had been approved by the Chemical Division Council.

0.2 The tear strength depends on the dimension of the test piece, speed of stretching, temperature of test and the stress distribution in the test piece; hence the test is satisfactory only for laboratory comparison and not as a service test. The tear strength is particularly susceptible to grain effects in vulcanized rubber.

0.3 Method of test for tear strength employing crescent test piece has already been published as Part XII of this standard.

0.4 This standard is mainly based on ASTM Designation D 624-54 ( Reapproved 1970 ) ( Standard method of test for tear resistance of vulcanized rubber ’ issued by the American Society for Testing and Materials.

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

1. SCOPE

1.1 This sta+rd ( Part XVII ) prescriber the method for determination of tear resistance of the usual grades of soft vulcanized rubber employing an angular test piece. This method is not suitable for the testing of the material ordinarily classed as hard rubber.

2. APPARATUS

21 Tensile Testing Machine - The machine shall be power driven and ofsuch capacity that the maximum load required to break the test specimen

l Rulci for rounding 0E numerical values ( r&.ruff ).

3

IS : 3400 ( Part XVII ) - 1974 i

shall not exceed 85 nor be less than 15 percent of the rated capacity. The rate of travel of the grip shall be 50 f 2 cm/mm and shall be uniform at all times. The machine shall be equipped with a type of grip which tightens automatically and exerts a uniform pressure across the gripping surfaces increasingly as the tension increases, so as to prevent uneven slipping? and to favour failure of the specimen in its constricted section. It is advisable to have at the end of each grip a positioning device so that all specimens are inserted to the same depth in the jaws and are perpendicular to the direction of pull.

NOTE - Inertia ( pendulum ) type dynamometers arc apt to give results which dither because of frictional and inertial effects. An inertia-less ( for examplr, electronic or optical transducer type ) dynamometer gives results which are free from these effects, and is therefore to be preferred.

2.1.1 Calibration of Temile Testing Machine -The load scale and the recording mechanism shall bc calibrated at least once a week to ensure that the load scale error does not exceed 2 percent of the applied load.

2.2 Die for Test Specimens -- The specimens for tear resistance test shall be stamped out with the steel die conforming to the dimensions shown in Fig. 1, the cutting edges of which shall be kept sharp and free of all nicks to avoid leaving ragged edges on the specimens. It is important that the apex of the 90-degree angle *be sharpened to provide a sharp comer. Good cutting edges are best obtained by careful honing. The rubber may be wetted with water or soap solution and shall be supported on a sheet of slightly yielding material ( namely, leather or cardboard) on a flat rigid surface. Normally all test pieces shall be prepared with grain at ri&t angles to their length.

+--=-- 100 MIN 4

9o” I

19 R 19

I

k2.5 R

25R

J

27 *

5QF

-204 7

Tolerance * 0’05

All dimensions in millimetres.

FIG. 1 DIES FOR TEAR TEST SPECIMENS

4

IS t 3400 ( Part XVII ) - 1974

3. TFST SPECIMEN

3.1 The test specimen shall conform to the shape shown in Fig. 1. The thickness of the specimen shall be measured, with the micrometer graduated to @I mm exerting a total force of 200 g/cm* on the rubber. Four measurements of thickness in the region of the test area shall be made including one at the apex of go-degree angle and the average value should be used. The thickness of the test piece shall not fall outside limits of 1.8 to 2.8 mm. The thickness in the region of the test area shall nowhere deviate by more than 2 percent from the mean.

NoTe -It is well known fact that vulcaniaed rubber exhibits a grain effect which influences its physical properties. In the case of heavily loaded compounds, the effect may produce a pronounced difference in physical properties. The grain direction shah be clearly marked on materials to be tested. running along the length of the specimen.

Usual practice is to test with the grain Data so obtained shah be recorded as tear

resistance ( pulling ) with the grain and it is assumed that unless otherwise specified, ail test specimens are to be prepared in this manner. Where grain effects are significant and are to be evaluated, an additional set of test specimens shall be cut with grain running across the specimen. Data so obtained shall be recorded as tear resistance ( pulling ) across the grain.

3.2 Number of Test Specimens -Three specimens per sample shall be tested for tear resistance. The value reported shall be the average of those observed. If any value deviates more than 20 percent from this average, two additional specimens shall be tested and the median of all five values shall be reported.

4. TEMPERATURE OF TEST

4.1 Carry out the test at 27 f 2°C unless otherwise specified. Some synthetic rubbers have markedly lower tear strength at elevated temperatures and hence tests may also have to be carried out at higher temperature, 100°C being the useful temperature.

5. PROCEDURE

5.1 Preparation of Sample from Finished Rubber Goods - IC fabric is attached or embodied in rubber sample, remove the same before cutting the test piece. Prefierably avoid the use of a swelling agent while removing the fabric, but benzene, chloroform or carbon tetrachloride may be used to wet the contacting surface, if necessary. Take care to avoid stretching of the rubber during the separation from the fabric, and if swelling liquid is used, allow the same to evaporate completely from the rubber surfaces after separation. Make the cloth marked surfaces smooth by buffing. Buff as and when necessary the rubber sample which is of uneven thickness or of thickness above the maximum specified for the test piece which is to be cut from it. If agreed to between the purchaser and the supplier, test pieces of thicknesses other than what have been prescribed

5

IS : 3400 ( Part XVII ) - 1974

in3.1 may be used. However, in such cases it shall be within the range of 0.8 to 3 mm. 1)uring buffmg avoid undue heating of the rubber.

5.2 Conditioning of the Moulded Test Slab - The properties of vulcanized rubber change continuously with time, these changes being particularly rapid during the first 24 hours after vulcanization. JIo not carry out any test within this period; for accurate comparisons .bctucen diff’crent rubbers it may be necessary to ensure that these are tested at substantially the same interval after \rulcanization. Protect test slabs and test pieces as far as possible from light. Condition samples after any necessary prcpara- tion at 27 4; 2°C for not less than 3 hours immediately before testing. When cart-yin? out tests at clevatcd temperature, the test piece shall be kept at that tcmpcraturc for 15 minutes.

5.5 Determination of Tear Resistance - Clamp the specimen for test in the jaxvs of the testing machine, taking care that the ‘ bite ’ of the jaws shall be at the rentre of the tab ends and in line with the direction of load application. Apply the load with a Jowcr jaw speed of 50 cm per minute. After rupture of the sprcimcn, note the breaking load from the dial or scale and record together with the average thickness of the spccimcn.

5.4 Calculation -- Tear strength is calculated by dividing the load in kg bv the tIli&ncss in centimetrc of the test specimen and expressed as kg/cm thickness.

5.5 Report ---- '1'11~ rtport sbaJJ state:

a) the calculated tear strength;

1~) direction in which test piece is cut relative to grain; and

c) temperature of test, if other than 27 f 2°C.

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