1、BRITISH STANDARDBS 2782-3: Method 323D: 1996ISO 6721-7: 1996Incorporating amendment no. 1Methods of testingPlastics Part 3: Mechanical properties g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3
2、g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58Method 323D: Torsional vibration Non-resonance methodICS 83.080BS 2782-3: Method 323D:1996of the Environment (Building Research Establishment)rtment of Trade and Industry (National Physical Laboratory)Committees responsible for this British StandardThCom
3、mittee reBrBrDepartment DepaThis British Standard, having been prepared under the direction of the Sector Board for Materials and Chemicals, was published under the authority ofthe Standards Board and comes into effect on 15 September 1996 BSI 2007The following BSI references relate to the work on t
4、his standard: Committee reference PRI/21 Draft for comment 95/122078 DCISBN 0 580 26067 4Electrical and Electronic Insulation Association (BEAMA Ltd.)GAMBICA (BEAMA Ltd.)Institute of MaterialsMinistry of DefencePackaging and Industrial Films AssociationPIRA InternationalRAPRA Technology Ltd.Royal So
5、ciety of ChemistryAmendments issued since publicationAmd. No. Date Comments16993 30 March 2007 See national foreworde preparation of this British Standard was entrusted to Technical PRI/21, Testing of plastics, upon which the following bodies were presented:itish Apparel and Textile Confederationiti
6、sh Plastics FederationBS 2782-3: Method 323D:1996 BSI 2007National forewordThis British Standard was published by BSI. It is the UK implementation of ISO 6721-7:1996, incorporating amendment 1:2007.ISO 6721-7 is one of a 10 part series of ISO 6721 methods of determination of the dynamic mechanical p
7、roperties of rigid plastics. ISO 6721-1, implemented as BS EN ISO 6721-1 (dual numbered BS 2782-3: Method 342A), is an introductory section which includes the definitions and all aspects that are common to the individual test methods described in the subsequent versions.The start and finish of text
8、introduced or altered by amendment is indicated in the 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 participation in its preparation was entrusted to Technical Committee
9、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 for its correct application.Compliance with a British Standard cannot c
10、onfer immunity from legal obligations.iblankBS 2782-3:Method 323D:19961 ScopeThis part of ISO 6721 describes a torsional, non-resonance method for determining the components of the shear complex modulus G*of solid polymers in the form of bars or rods at frequencies typically in the range 0,001 Hz to
11、 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 method is suitable for measuring dynamic storage moduli ranging from about 10 MPa, which is typical of values obtained for stiff rubbers, to va
12、lues of about 10 GPa which are representative of fibre-reinforced plastics. Although materials with moduli less than 10 MPa may be studied, more accurate measurements of their dynamic properties can be made using simple shear (see ISO 6721-6) or torsional deformations of thin layers between parallel
13、 plates.This method is particularly 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). T
14、he availability of data determined over wide ranges of both frequency and temperature enable master plots to be derived, using frequency-temperature shift procedures, which display dynamic properties over an extended frequency range at different temperatures.Although loss factors below 0,1 may be mo
15、re accurately determined using the torsion pendulum (see ISO 6721-2), the method described in this part of ISO 6721 enables a much wider and continuous frequency range to be covered.2 Normative referencesThe following standards contain provisions which, through reference in this text, constitute pro
16、visions 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 the most recent editions of the standards indicat
17、ed 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 mechanical properties Part 6: Shear vibration Non-reso
18、nance method.3 DefinitionsSee ISO 6721-1:1994, clause 4.4 PrincipleThe specimen is subjected to a sinusoidal torque or angular displacement at a frequency significantly below the fundamental torsion resonance frequency (see 10.2.1). The amplitudes of the torque and displacement cycles applied to the
19、 specimen and the phase angle between these cycles are measured. The storage and loss components of the shear complex modulus and the loss factor are calculated using equations given in clause 10 of this part of ISO 6721.5 Test device5.1 Loading assemblyThe requirements on the apparatus are that it
20、shall permit measurements of the amplitudes of, and phase angle between, the torque and angular displacement cycles for a specimen subjected to a sinusoidal torque or displacement. Various designs of apparatus are possible, as illustrated schematically in Figure 1a) and Figure 1b). In Figure 1a), a
21、sinusoidal angular displacement is generated by the drive unit D and applied to one end of the specimen S through the moving clamp C1. The amplitude and frequency of the angular displacement are variable and monitored by the rotary displacement transducer R. The specimen is held at the opposite end
22、by a fixed clamp C2 and thus undergoes sinusoidal torsional deformations. The sinusoidal torque applied in deforming the specimen is monitored by a torque transducer T connected to C2. The members between the clamp C1 and D and between C2and T should be much stiffer than the specimen and should have
23、 a low thermal conductance if the specimen is to be enclosed in a temperature-controlled cabinet (see note 1). Where tests are carried out at elevated temperatures, a facility shall be included in the loading assembly to avoid buckling of the specimen resulting from thermal expansion.NOTE 1 Whilst e
24、ach member of the loading assembly may have a much higher stiffness than the specimen, the presence of clamped or bolted connections can significantly increase the apparatus compliance. It may then be necessary to apply a compliance correction as described in 10.2.3. BSI 2007 1ISO 6721-2:1994, Plast
25、ics Determination of dynamic mechanical properties Part 2: Torsion-pendulum method.BS 2782-3: Method 323D:1996Various other loading assemblies may be employed as alternatives to that detailed above. For example, the torque on the specimen may be calculated from the current supplied to the drive unit
26、, thus eliminating the need for a separate torque transducer. With this method Figure 1b), it should be recognized that part of the torque generated by the drive current is used to accelerate the drive shaft and also to deform any drive shaft suspension (Su) in parallel with the specimen. That part
27、of the generated torque used to deform the specimen shall be determined with the aid of a separate calibration with the specimen absent. Alternatively, the suspension member may be replaced by an air bearing, thereby making the torsional rigidity of the suspension zero.5.1.1 ClampsThe clamps shall b
28、e capable of gripping the test specimen with a force which is sufficient to prevent the specimen from slipping during the torsional deformation and maintaining the force at low temperatures.The separation between the two clamps should preferably be variable so that specimens of different length can
29、be accommodated and length corrections may be determined (see 10.2.4). A facility to permit small variations in the clamp separation would also allow for thermal expansion of the specimens and is necessary to avoid errors in the apparent moduli due to buckling of the specimens at high temperatures.A
30、ny misalignment of the clamps with respect to the force transducer will produce a lateral component of the torque applied to the transducer during loading of the specimen. The alignment of the loading assembly and test specimen shall be such that any lateral component recorded by the transducer is l
31、ess than 1 % of the applied torque.5.1.2 TransducersThe term transducer in this part of ISO 6721 refers to any device capable of measuring the applied torque or displacement, or the ratio of these quantities, as a function of time. The calibrations of the transducers shall be traceable to national s
32、tandards for the measurement of torque and length. The calibrations shall be accurate to 2 % of the minimum torque and displacement cycle amplitudes applied to the specimen for the purpose of determining dynamic properties.5.2 Electronic data-processing equipmentData-processing equipment shall be ca
33、pable of recording the torque and displacement cycle amplitudes to an accuracy of 1 % the phase angle between the torque and displacement cycles to an accuracy of 0,1 and the frequency to an accuracy of 10 %.5.3 Temperature measurement and controlSee ISO 6721-1:1994, subclauses 5.3 and 5.5.5.4 Devic
34、es for measuring test specimen dimensionsSee ISO 6721-1:1994, subclause 5.6.6 Test specimensSee ISO 6721-1:1994, clause 6.6.1 Shape and dimensionsTest specimens in the form of rectangular bars or cylindrical rods are recommended. The width and thickness of the bars and the diameter of the rods shall
35、 not vary along the specimen length by more than 2 % of a mean value. Dimensions of the specimens are not critical, although length corrections for clamping effects can be minimized by increasing the length of the specimen and, for rectangular specimens, these corrections become negligible for certa
36、in values of b/d (see 10.1 and 10.2.4). For test conditions under which the storage moduli are high ( 1 GPa), sufficiently long, thin specimens should preferably be employed so that angular displacements are generated that may be measured with high accuracy. Alternatively, when the storage moduli ar
37、e low ( 100 MPa), relatively short, thick specimens may be required to achieve sufficient accuracy in the measurement of torque.NOTE 2 A variation in dynamic properties may be observed between specimens of different thickness prepared by injection moulding owing to slight differences which may be pr
38、esent in the structure of the polymer in each specimen.6.2 PreparationSee ISO 6721-1:1994, subclause 6.2.7 Number of specimensSee ISO 6721-1:1994, clause 7.8 ConditioningSee ISO 6721-1:1994, clause 8.2 BSI 2007BS 2782-3:Method 323D:19969 Procedure9.1 Test atmosphereSee ISO 6721-1:1994, subclause 9.1
39、.9.2 Measuring the cross-section of the specimenSee ISO 6721-1:1994, subclause 9.29.3 Clamping the specimenMount the specimen between the clamps using a clamping force that is sufficient to prevent slip under all test conditions. If measurements are observed to depend upon clamp pressure, then a con
40、stant pressure should preferably be used for all measurements, especially when applying a length correction (see 10.2.4 and note 3).NOTE 3 If measurements are observed to depend upon clamp pressure, then the clamped area of the specimen is probably too small. A larger clamp face or a wider specimen
41、should eliminate this problem.9.4 Varying the temperatureSee ISO 6721-1:1994, subclause 9.4.9.5 Performing the testA dynamic torque shall be applied by the drive motor which yields torque and displacement amplitudes for the specimen that can be measured to the accuracy specified in 5.1.2.NOTE 4 If t
42、he maximum shear strain within the specimen exceeds the limit for linear behaviour, then the derived dynamic properties will depend on the magnitude of the applied displacement. The limiting strain varies with the composition of the polymer and the temperature and is typically in the region of 0,2 %
43、 for glassy plastics. !The dynamic strain range for linear behaviour can be explored by varying the dynamic displacement amplitude at a constant frequency and recording any change in dynamic stiffness with strain amplitude. A low frequency should be used for this purpose to minimize any temperature
44、increase caused by mechanical loss. However, it should be noted that, because of the non-uniform strain in the specimen in this test, the onset of non-linear behaviour will be less apparent than in tests where the strain distribution is uniform. If non-linear behaviour is detected in the strain rang
45、e of interest, the dynamic strain limit shall be recorded in the test report.“The amplitudes of, the phase difference between and the frequency of the torque and displacement signals and the temperature of the test shall be recorded. Where measurements are to be made over ranges of frequency and tem
46、perature, it is recommended that the lowest temperature be selected first and measurements be made with increasing frequency, keeping the temperature constant. The frequency range is then repeated at the next higher temperature (see ISO 6721-1:1994, subclause 9.4).For those test conditions under whi
47、ch the polymer exhibits medium or high loss (for example in the glass-rubber transition region), the energy dissipated by the polymer may raise its temperature sufficiently to give a significant change in dynamic properties. Any temperature rise will increase rapidly with increasing strain amplitude
48、 and frequency. If the data processing electronics is capable of analysing the transducer outputs within the first few cycles, than the influence of any temperature rise will be minimized. Subsequent measurements will then change with time as the specimen temperature continues to rise, and such obse
49、rvations will indicate the need to exercise some caution in the presentation and interpretation of results.10 Expression of results10.1 SymbolsLalength of specimen between the two clamps, in metresl length correction term for clamping, in metresb width of rectangular specimen, in metresd thickness of rectangular specimen, in metresr radius of cylindrical specimen, in metresf measurement frequency, in hertzuAmeasured amplitude of the dynamic angular displacement, in radiansTAmeasured amplitude of the dynamic torque applied to the specimen, in newton metresdGa,
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