BS ISO 6721-4 pdf free download
BS ISO 6721-4-2019 pdf free download.Plastics — Determination of dynamic mechanical properties Part 4: Tensile vibration — Non-resonance method.
This document describes a forced, non-resonance method for determining the components of the tensile complex modulus E* of polymers at frequencies typically in the range 0,01 Hz to 100 Hz. NOTE Higher frequency measurements can be made, but significant errors in the dynamic properties measured are likely to result (see 10.2.2 and 10.2.3). The method is suitable for measuring dynamic storage moduli in the range 0,01 GPa to 5 GPa. Although materials with moduli outside this range can be studied, alternative modes of deformation are intended to be used for higher accuracy [i.e. a shear mode for G′ < 0,01 GPa (see ISO 6721-6) and a flexural mode for E′ > 5 GPa (see ISO 6721-3 or ISO 6721-5)]. This method is particularly suited to the measurement of loss factors and can 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). The availability of data determined over wide ranges of both frequency and temperature enables master plots to be derived, using frequency-temperature shift procedures, which display dynamic properties over an extended frequency range at different temperatures.
2 Normative references The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 6721-1, Plastics — Determination of dynamic mechanical properties — Part 1: General principles
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 6721-1 apply.
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4 Principle
The specimen is subjected to a sinusoidal tensile force or deformation at a frequency significantly below the fundamental resonance frequency for the clamped/free longitudinal mode (see 10.2.2). The amplitudes of the force and displacement cycles applied to the specimen and the phase angle between these cycles are measured. The storage and loss factor are calculated using formulae given in Clause 10.
5.4 Devices for measuring test specimen dimensions
According to ISO 6721-1.
6 Test specimens
6.1 General
According to ISO 6721-1.
6.2 Shape and dimensions
Test specimens of rectangular cross-section are recommended to facilitate load introduction. The width and thickness shall not vary along the specimen length by more than 3 % of the mean value.
It is also recommended that the length of the specimen between the clamps be longer than six times the specimen width in order to make the constraint by the clamps to free lateral contraction of the specimen negligible. Where high accuracy of results is requested, a specimen length is recommended which will permit a clamp separation of about 50 mm to 100 mm or more in order to achieve adequate accuracy in the determination of the dynamic tensile strain. Cross-sectional dimensions are not critical. For test conditions under which the polymer exhibits glassy behaviour, the cross-sectional area shall be selected sufficiently small so that the vibrator is able to generate tensile displacements that may be measured with adequate accuracy. Alternatively, when the polymer exhibits rubbery behaviour, a larger cross-sectional area may be necessary to achieve sufficient accuracy in the measurement of force. NOTE A variation in dynamic properties can be observed between specimens of different thickness prepared by injection moulding owing to differences which can be present in the structure of the polymer in each specimen.BS ISO 6721-4 pdf download.
