1、BRITISH STANDARDBS 2782-3: Method 323B:1996ISO 6721-5: 1996Incorporating amendment no. 1Methods of testingPlastics Part 3: Mechanical properties g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g
2、37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58Method 323B: Flexural vibration Non-resonance methodICS 83.080BS 2782-3:Method 323B:1996National forewordThis BritiISO 67serigdefidescribThis British Standard, having been prepared under the direction of the Sector Board for Materials and Chemicals, was p
3、ublished under the authority of the Standards Board and comes into effect on 15 December 1996 BSI 2007ISBN 0 580 27085 6the text by tags !“. Tags indicating changes to ISO text carry the number of the ISO amendment. For example, text altered by ISO amendment 1 is indicated in the text by !“.The UK p
4、articipation in its preparation was entrusted to Technical Committee PRI/21, Testing of plastics.A list of organizations represented on PRI/21 can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible fo
5、r its correct application.Compliance with a British Standard cannot confer immunity from legal obligations.Amendments issued since publicationAmd. No. Date Comments16994 30 March 2007 See national forewordsh Standard was published by BSI. It is the UK implementation of 21-5:1996, incorporating amend
6、ment 1:2007. It is one of a ten part ries of methods of determination of the dynamic mechanical properties of id plastics. Part 1 of ISO 6721 is an introductory section which includes the nitions and all aspects that are common to the individual test methods ed in the subsequent versions.The start a
7、nd finish of text introduced or altered by amendment is indicated in BS 2782-3:Method 323B:1996 BSI 2007ContentsPageNational Foreword Inside front coverForeword iiiText of BS ISO 6721-5:1996 1iiiblankBS 2782-3:Method 323B:1996BS 2782-3:Method 323B:1996ContentsPage1Scope 12 Normative references 13 De
8、finitions 14 Principle 15 Apparatus 16 Test specimens 27 Number of specimens 28 Conditioning 29 Procedure 210 Expression of results 311 Precision 512 Test report 5Figure 1 Schematic diagrams of suitable loading assemblies for determining dynamic moduli under flexure 6Figure 2 Schematic diagram of an
9、 alternative loading assembly for determining dynamic flexural moduli, employing measurement of the current to the vibrator to determine the force on the specimen 7ii BSI 2007BS 2782-3:Method 323B:1996 BSI 2007ForewordISO (the International Organization for Standardization) is a worldwide federation
10、 of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee.
11、International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.Draft International Standards adopted by the technical
12、 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 Standard ISO 6721-5 was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 2, Mechanical propert
13、ies. 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-resonance method; Part 7: Torsional vibration Non-resonanc
14、e method; Part 8: Longitudinal and shear vibration Wave-propagation method; Part 9: Tensile vibration Sonic-pulse propagation method; Part 10: Dynamic shear viscosity using a parallel-plate oscillatory rheometer.iiiivblankBS 2782-3:Method 323B:1996 1 ScopeThis part of ISO 6721 describes a flexural,
15、non-resonance method for determining the components of the Youngs complex modulus E*of polymers at frequencies typically in the range 0,01 Hz to 100 Hz. !Higher-frequency measurements can be made, but significant errors may be obtained in the dynamic properties measured (see 10.2.1 and 10.2.2).“ The
16、 method is suitable for measuring dynamic storage moduli in the range 10 MPa to 200 GPa. Although materials with moduli less than 10 MPa may be studied, more accurate measurements of their dynamic properties can be made using shear modes of deformation (see part 6 of ISO 6721).This method is particu
17、larly suited to the measurement of loss factors greater than 0,1 and may therefore be conveniently used to study the variation of dynamic properties with temperature and frequency through most of the glass-rubber relaxation region (see ISO 6721-1:1994, subclause 9.4). The availability of data determ
18、ined over wide ranges of both frequency and temperature enables master plots to be derived, using frequency/temperature shift procedures, which present dynamic properties over an extended frequency range at different temperatures.2 Normative referencesThe following standards contain provisions which
19、, through reference in this text, constitute provisions of this part of ISO 6721. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this part of ISO 6721 are encouraged to investigate the possibility of applying t
20、he most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards.ISO 6721-1:1994, Plastics Determination of dynamic mechanical properties Part 1: General principles.ISO 6721-6:1996, Plastics Determination of dynamic mechan
21、ical properties Part 6: Shear vibration Non-resonance method.3 DefinitionsSee ISO 6721-1:1994, clause 3.4 PrincipleA test specimen is subjected to a sinusoidal transverse force or displacement at a frequency significantly below the fundamental flexural resonance frequency (see 10.2.1). The amplitude
22、s of the force and displacement cycles applied to the specimen and the phase angle between these cycles are measured. The storage and loss components of the Youngs complex modulus and the loss factor are calculated using equations given in clause 10 of this part of ISO 6721.5 Apparatus5.1 Loading as
23、semblyThe requirements for the loading assembly are that it shall permit measurements of the amplitudes of, and phase angle between, the force and displacement cycles for a specimen subjected to a transverse sinusoidal force or displacement. Various designs of apparatus are possible, as illustrated
24、schematically in Figure 1 and Figure 2. In Figure 1 a), a sinusoidal displacement is generated by the vibrator V and applied to the specimen S through moving clamps C1located close to the opposite ends of the specimen. The amplitude and frequency of the vibrator table displacement are variable and m
25、onitored by the transducer D. The specimen is held at its centre by a fixed clamp C2and thus undergoes sinusoidal flexural deformations. The sinusoidal force applied in deforming the specimen is monitored by a force transducer F connected to C2. The members between the clamps C1and V, and between C2
26、and F, shall be much stiffer than the specimen and shall have a low thermal conductance if the specimen is to be enclosed in a temperature-controlled cabinet.NOTE 1 Whilst each member of the loading assembly may have a much higher stiffness than the specimen, the presence of clamped or bolted connec
27、tions can significantly increase the apparatus compliance. It may then be necessary to apply a compliance correction as described in 10.2.3.Various other loading assemblies may be employed as alternatives to that detailed above. For example, the specimen may be simply supported and deformed in three
28、-point flexure, as illustrated in Figure 1 b). Furthermore, the force on the specimen may be calculated from the current supplied to the vibrator, thus eliminating the need for a separate force transducer. With this method (see Figure 2), it should be recognized that part of the force generated by t
29、he vibrator current is used to accelerate the drive shaft and to deform the drive-shaft suspension Su in parallel with the specimen. That BSI 2007 1part of the generated force used to deform the specimen must be determined with the aid of a separate calibration with the specimen absent.BS 2782-3:Met
30、hod 323B:19965.1.1 Load stageThe clamps shall be capable of gripping the test specimen with a force which is sufficient to prevent the specimen from slipping during the flexural deformation, and to maintain the force at low temperatures.With the simply supported specimen Figure 1 b), the supporting
31、rollers shall contact the specimen along parallel lines and have radii sufficiently large to avoid significant indentation of the specimen and thereby minimize consequent errors in the measured moduli and loss factors.The separation between the two outer clamps and between the outer supports shall b
32、e variable so that specimens of different length can be accommodated and length corrections may be determined for the clamped specimens (see 10.2.4). A facility to permit small variations in the clamp separation Figure 1 a) would also allow for thermal expansion of the specimens and is necessary to
33、avoid errors in the apparent moduli due to buckling of the specimens at high temperatures.Any misalignment of the load stage with respect to the force transducer will produce a lateral component of the force applied to the transducer during loading of the specimen. The alignment of the loading assem
34、bly and test specimen shall be such that any lateral component recorded by the transducer is less than 1 % of the longitudinal force.5.1.2 TransducersThe term transducer in this part of ISO 6721 refers to any device capable of measuring the applied force or displacement, or the ratio of these quanti
35、ties, as a function of time. The calibration of the transducers shall be traceable to national standards for the measurement of force and length. The calibration shall be accurate to 2 % of the minimum force and displacement cycle amplitudes applied to the specimen for the purpose of determining dyn
36、amic properties.5.2 Electronic data-processing equipmentData-processing equipment shall be capable of recording the force and displacement cycle amplitudes to an accuracy of 1 %, the phase angle between the force and displacement cycles to an accuracy of 0,1 and the frequency to an accuracy of 10 %.
37、5.3 Temperature measurement and controlSee ISO 6721-1:1994, subclauses 5.3 and 5.5.5.4 Devices for measuring test specimen dimensions6 Test specimensSee ISO 6721-1:1994, clause 6.6.1 Shape and dimensionsTest specimens of rectangular cross-section are recommended to facilitate load introduction. The
38、width and thickness shall not vary along the specimen length by more than 2 % of the mean value. The dimensions of the specimens are not critical although, for isotropic materials, values of La/d 16 for clamped specimens and La/d 8 for simply supported specimens would make corrections for shear defo
39、rmation negligible (see 10.1 and 10.2). Also values of La/b 6 for clamped specimens and La/b 3 for simply supported specimens are recommended to avoid significant errors associated with constraints to deformations along the width direction (anticlastic curvature) near to the clamps or central suppor
40、t (see 10.1). For test conditions under which the storage moduli are high ( 50 GPa), sufficiently long, thin specimens shall be employed so that displacements are generated that may be measured with high accuracy. Alternatively, when the storage moduii are low ( 0,08s.(5).(6) 0,1F.(7).(8)4 BSI 2007B
41、S 2782-3:Method 323B:1996 10.2.3 Correction for apparatus complianceIf kais greater than 0,02 k, then the compliance of the test assembly is not negligible and the measured displacement differs significantly from that of the specimen. The following correction shall then be applied:where dEis given b
42、y equation (11).The value of k cos dEobtained from equation (9) shall be used in place of kacos dEain equation (1) or (2) to give a more accurate estimate for Ea.NOTE 7 The compliance correction is unnecessary if the displacement transducer is located so as to measure the relative displacement of ce
43、ntral and outer clamps or supports.10.2.4 Application of a length correctionUsing the measured clamp separation Lafor the specimen length in equation (1) takes no account of some distortion of the specimen within and around the clamps. Applying a small correction to Lasuch that the effective length
44、is La+ l, and assuming l is independent of La, yields from equation (1)where Eais the apparent storage modulus corrected for apparatus compliance, if necessary, and the length correction has been ignored in the small shear-correction term.A value for l may be determined from measurements of Eafor a
45、series of clamp separations La. From equation (10), a plot of La/Ea1/3against Laenables l to be determined from the intercept at La/Ea1/3= 0 and E to be determined from the gradient.NOTE 8 The value of l will vary with the cross-sectional dimensions of the specimen and with temperature if this cause
46、s significant changes in dynamic modulus.10.3 Calculation of the Youngs loss factor tan dEAn approximate value for the Youngs loss factor is tan d .If kais greater than 0,02 kthen the compliance of the loading assembly will influence the accuracy of the phase angle measurement. The loss factor shall
47、 then be obtained using the equationNOTE 9 If the origin of the source of compliance in the loading assembly arises through clamped or bolted connections, there may be a contribution from friction to the measured phase angle dEa. The magnitude of the resulting error increases with the ratio ka/k. Th
48、is source of error can be avoided by locating the displacement transducer so that the relative displacement of the central and outer clamps or supports is measured.10.4 Calculation of the Youngs loss modulusCalculate the loss modulus E from the equation10.5 Presentation of data as a function of temp
49、eratureSee ISO 6721-1:1994, subclause 9.4.11 PrecisionThe precision of this test method is not known because interlaboratory data are not available. When interlaboratory data are obtained, a precision statement will be added at the following revision.12 Test reportThe test report shall contain the following information:.(9).(10).(11)E = E tan dE.(12)a) a reference to this part of ISO 6721;b) to m) see ISO 6721-1:1994, clause 12;n) the maximum dynamic strain amplitude, given approximately by 3dsA/L for clamped s
