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1、W 4851903 Ob09821 T45 INTERNATIONAL STANDARD 6721-21994 TECHNICAL CORRIGENDUM 1 Pu blished 199543-1 5 INTERNATIONAL ORGANIZATION FOR STANDARDIZATION MMiPYWPODHAR OPrAHM3AilMR no C T W P M W M M ORGANISATION INTERNATIONALE DE NORMALISATION Plastics - Determination of dynamic mechanical properties - P
2、art 2: Torsion-pendu I um met hod TECHNICAL CORRIGENDUM 1 Plastiques - Dtermination des proprits mcaniques dynamiques - Partie 2: Mthode au pendule de torsion RECTIFICATIF TECHNIQUE I Technical corrigendum 1 to International Standard IS0 6721-2:1994 was prepared by Technical Committee lSO/TC 61, Pla
3、stics, Subcommittee SC 2, Mechanical properties. Page IO Annex C Replace the last sentence in the left-hand column by: “If the range of hlb is limited to a maximum value of 0,6 in equation (2) and a minimum value of 0,6 in equation (31, the maximum error is 0.9 %.“ ICs 83.080.00 Ref. No. IS0 6721-21
4、994/Cor.l:1995(E) Descriptors: plastics, rigid plastics, tests, torsion tests, determination, mechanical properties, dynamic properties, shear modulus, test equipment, torsion pendulums. (o IS01995 Printed in Swberland IS0 6723 PT*Z 94 4853903 0578463 323 I NT E R NAT I O NA L STANDARD IS0 6721-2 Fi
5、rst edition 1994-1 1-01 Plastics - Determination of dynamic mechanical properties - Part 2: Torsion-pendu I um method Plastiques - Dtermination des proprits mcaniques dynamiques - Partie 2: Mthode au pendule de torsion Reference number IS0 6721-211 994(E) -,-,- IS0 6723 PT*2 94 = 4853903 0578464 268
6、 IS0 6721 -2:1994(E) Foreword IS0 (the International Organization for Standardization) is a worldwide federation of national standards bodies (IS0 member bodies). The work of preparing International Standards is normally carried out through IS0 technical committees. Each member body interested in a
7、subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and nongovernmental, in liaison with ISO, also take part in the work. IS0 collaborates closely with the International Electrotechnical Commission
8、(IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. International S
9、tandard IS0 6721-2 was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 2, Mechanical properties. Together with IS0 6721-1, it cancels and replaces IS0 537:1989, which has been technically revised. IS0 6721 consists of the following parts, under the general title Plastics - Deter
10、mination of dynamic mechanical properties: - Part 1: General principles - Part 2: Torsion-pendulum method - Part 3: Flexural vibration - Resonance-curve method - Part 4: Tensile vibration - Non-resonance method - Part 5: Flexural vibration - Non-resonance method - Part 6: Shear vibration - Non-reson
11、ance method - Part 7: Torsional vibration - Non-resonance method Annex A forms an integral part of this part of IS0 6721. Annexes B, C and D are for information only. O IS0 1994 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or
12、by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the publisher. International Organization for Standardization Case Postale 56 CH-1 21 1 Genve 20 Switzerland Printed in Switzerland ii -,-,- IS0 6723 PT*Z 94 4851903 0578465 I T 4 INTERNA
13、TIONAL STANDARD 8 IS0 IS0 6721 -2:1994( E) Plastics - Determination of dynamic mechanical properties - Part 2: Torsion-pendu1 u m method 1 Scope This part of IS0 6721 specifies two methods (A and B) for determining the linear dynamic mechanical properties of plastics, .e. the storage and loss com- p
14、onents of the torsional modulus, as a function of temperature, for small deformations within the fre- quency range from 0,l Hz to 10 Hz. The temperature dependence of these properties, measured over a sufficiently broad range of tempera- tures (for example from - 50 OC to + 150 “C for the majority o
15、f commercially available plastics), gives in- formation on the transition regions (for example the glass transition and the melting transition) of the polymer. It also provides information concerning the onset of plastic flow. The two methods described are not applicable to non-symmetrical laminates
16、 (see IS0 6721-3:1994, Plastics - Determination of dy- namic mechanical properties - Part 3: Flexural vi- bration - Resonance-curve method). The methods are not suitable for testing rubbers, for which the user is referred to IS0 4663:1986, Rubber - Determi- nation of dynamic behaviour of vulcantzate
17、s at low frequencies - Torsion pendulum method. 2 Normative reference The following standard contains provisions which, through reference in this text, constitute provisions of this part of IS0 6721. At the time of publication, the edition indicated was valid. All standards are subject to revision,
18、and parties to agreements based on this part of IS0 6721 are encouraged to investigate the possibility of applying the most recent edition of the standard indicated below. Members of IEC and IS0 maintain registers of currently valid International Standards. IS0 6721-1:1994, Plastics - Determination
19、of dy- namic mechanical properties - Part I: General prin- ciples. 3 Definitions See IS0 6721-1:1994, clause 3. 4 Principle A test specimen of uniform cross-section is gripped by two clamps, one of them fixed and the other con- nected to a disc, which acts as an inertial member, by a rod. The end of
20、 the specimen connected to the disc is excited, together with the disc, to execute freely decaying torsional oscillations. The oscillation mode is that designated IV in IS0 6721-1:1994, table 2, and the type of modulus is G, as defined in IS0 6721-1 :1994, table 3. The inertial member is suspended e
21、ither from the specimen (method A, see figure I), or from a wire (method B, see figure2). In the latter case, the wire is also part of the elastically oscillating system. 1 IS0 6723 PT*Z 94 9 4851903 0574bb 030 I.-) .- - - IS0 6721-2:1994(E) Upper (fixed) clamp Temperature-controlled chamber -Test s
22、pecimen -Lower (movable) clamp n y inertial member Figure 1 - Apparatus for method A A Counterweight I- Wire I inertial member r Rod Upper (movable) clamp Test specimen Temperature-controlled chamber Lower (fixed) clamp L Figure 2 - Apparatus for method B 2 IS0 6723 PT*2 94 m 4853903 05784b7 T77 0 I
23、S0 During a temperature run, the same inertial member can be used throughout the whole run, which results in a frequency decreasing naturally with increasing temperature, or the inertial member can be replaced at intervals by a member of different moment of in- ertia in order to keep the frequency a
24、pproximately constant. During the test, the frequency and the decaying am- plitude are measured. From these quantities, the storage component Gto and loss component G“to of the torsional complex modulus G;, can be calculated. 5 Test apparatus 5.1 Pendulum Two types of torsion pendulum are specified
25、for use with this part of IS0 6721: a) the inertial member is suspended from the test specimen and the lower end of the specimen is excited (method A, figure 1); b) the inertial member is suspended from a wire at- tached to a counterweight and the upper end of the specimen is excited (method B, figu
26、re 2). Both types of pendulum consists of an intertial mem- ber, two clamps for gripping the specimen (one of which is connected to the inertial member by a rod) and a temperature-controlled chamber enclosing the specimen and the clamps. For method B, a counter- weight and connecting wire are also r
27、equired. 5.2 Inertial member The moment of inertia I of the inertial member, which may be made of aluminium, for instance, shall be selected as a function of the torsional stiffness of the specimen, so that the temperature-dependent natural frequency of the system lies between approximately 0,l Hz a
28、nd 10 Hz. When testing standard specimens (see 6.11, a mo- ment of inertia I of about 3 x kg.m2 is rec- ommended if the same inertial member is to be used throughout a run. NOTE 1 of I of about 5 x For certain materials, e.g. filled polymers, a value kg-m may be necessary. If a constant frequency is
29、 desired over a broad tem- perature range, interchangeable inertial members with different values of I may be used, thereby permitting the moment of inertia to be varied in steps of less than 20 %, .e. the frequency to be corrected in steps of less than 10 %. When testing standard specimens IS0 6721
30、 -2:1994(E) (see 6.1) at a frequency of about 1 Hz, a maximum moment of inertia of about 3 x IOp3 kg.m2 is rec- ommended. 5.2.1 Method A (see figure 1) The total mass of the inertial member, the lower clamp, and the connecting rod shall be such that the weight W carried by the specimen is not too hi
31、gh see annex A, equation (A.211. 5.2.2 Method B (see figure21 The total mass of the inertial member, the upper clamp and the rod must be balanced by a suitable counterweight, so that the longitudinal force W acting on the specimen is minimized see annex A, equation (A.2). The wire supporting these p
32、arts is part of the elastically oscillating system. 5.3 Clamps The clamps shall be designed to prevent movement of the portion of the specimens gripped within them. They shall be self-aligning in order to ensure that the specimen axis remains aligned with the axis of rota- tion and the test specimen
33、 remains adequately se- cured over the whole temperature range without distortion occurring, thus allowing the free length of the specimen to be accurately determined. The movable clamp shall be of low mass. The moment of inertia of the whole system (consist- ing of the movable clamp, the inertial m
34、ember and the connecting rod) shall be determined experimentally. To prevent heat passing from the specimen out of the temperature-controlled chamber and in the opposite direction, the rod connecting the movable clamp and the inertial member shall be thermally non- conducting. 5.4 Oscillation-induci
35、ng device The oscillation-inducing device shall be capable of ap- plying to the pendulum a torsional impulse such that the pendulum oscillates initially through an angle of not more than 1,5“ in each direction for normal ma- terials, or not more than 3“ in each direction for low- modulus materials (
36、such as elastomers). 5.5 Oscillation-frequency and oscillation-amplitude recording equipment Optical, electrical or other recording systems may be used provided they have no significant influence on 3 -,-,- IS0 6723 PT*2 94 W 4851903 05784b8 903 W IS0 6721-2:1994(E) 0 IS0 the oscillating system. The
37、 entire equipment for measuring frequency and amplitude shall be accurate to f 1 % (within the transition region f 5 %). 7 Number of specimens See IS0 6721-1:1994, clause 7. 5.6 Temperature-controlled chamber 8 Conditioning See IS0 6721-3:1994, subclause 5.3. See IS0 6721-1:1994, clause 8. 5.7 Gas s
38、upply Air or inert-gas supply for purging purposes. 5.8 Temperature-measurement device See IS0 6721-1:1994, subclause 5.5. If mechanical conditioning of the specimen is re- quired, the specimen shall be twisted through an an- gle greater than 5“ but less than 90“ in both directions about the torsion
39、al-test axis and returned to its normal position. 9 Procedure 5.9 Devices for measuring test-specimen 9.1 Test atmosphere dimensions See IS0 6721-1 :1994, subclause 5.6. 6 Test specimens See IS0 6721-1 :I 994, subclause 9.2. See IS0 6721-1:1994, subclause 9.1. 9.2 Measurement of specimen cross-secti
40、on See IS0 6721-1:1994, clause 6. 6.1 Shape and dimensions Rectangular test specimens having the following di- mensions are recommended: free length, L: width, b: thickness, h: 40 mm to 120 mm, preferably 50 mm 5 mm to 1 1 mm, preferably 10 mm 0,15 mm to 2 mm, preferably 1 mm Specimens which are rec
41、tangular in cross-section but whose thickness and/or width varies along the main axis of the specimen by more than 3 % of the mean value shall not be used. When comparing different materials, the dimensions of the specimens shall be identical. Specimen dimensions differing from the preferred ones (5
42、0 mm x 10 mm x 1 mm) should be chosen to conserve geometric similarity with the preferred specimen shape. Alternative specimen shapes may be used (e.g. cylin- drical or tubular); in such cases, dimensions and tol- erances shall be agreed upon by the interested parties. 6.2 Preparation See IS0 6721-1
43、 :1994, subclause 6.2. 9.3 Mounting the test specimens Clamp the test specimen between the upper and lower clamps. The longitudinal axis of the test speci- men shall coincide with the axis of rotation of the os- cillating system. Any misalignment of the specimen will cause lateral oscillations that
44、will interfere with the normal oscillation process. After clamping the test specimen, measure the dis- tance between the clamps (the free length L I to f 0,5 %. When setting up the oscillating system in the chamber, check to make sure that the test speci- men is not stressed. After assembling the os
45、cillating system complete with test specimen, and checking its alignment, start the heating or cooling (see 9.4). 9.4 Varying the temperature See IS0 6721-1 :1994, subclause 9.4. 9.5 Performing the test Start the free oscillations by setting the pendulum in motion using the oscillation-inducing devi
46、ce (5.4). Record the oscillation frequency and the oscillation amplitude as it decays. Check that no amplitude decay is caused either by friction between moving and fixed parts of the appar- 4 IS0 6723 PT*2 94 = 4853903 0578469 84T 8 IS0 IS0 6721 -2:1994(E) atus or non-linear behaviour of the materi
47、al under test (see IS0 6721-1:1994, annex B). If the frequency is kept fixed during a temperature run, ensure that the inertial member is changed as Gt, torsional storage modulus, in pascals, of the Gto torsional loss modulus, in pascals, of the speci- specimen men and when necessary. NOTES 10 Expre
48、ssion of results 2 For reasons given in annex 6, the symbol Fd used for the damping correction factor has a different subscript from that used previously in IS0 537 (now withdrawn). 1 0 . 1 Symbols and correction factors 3 Equations (2) and (3) are only approximately valid, the b maximum error being
49、 0,9 % (see annex C). h 4 The dimensional factor does not include any length cor- rections to allow for clamping effects. Therefore only L measurements carried out on specimens with the same thickness, width and length ratios will yield accurately I moment of inertia, expressed in kilogram metre comparable results (see IS0 6721-1 :1994, table 1 and note 7). width, in metres, of a rectangular specimen thickness, in metres, of a recta