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This part of ISO 6721 describes a compressive vibration, non-resonance method for determining the components of the compressive complex modulus E* of polymers at frequencies typically in the range 0,01 Hz to 100 Hz. The method is suitable for measuring dynamic storage moduli of semi-rigid polymers in the range 1 MPa to 1 GPa (see Notes 1 and 2).

NOTE 1 The method is applicable to the following semi-rigid polymers:

- low-density polyethylene, ultra-high-molecular-weight polyethylene, polybutylene, and ethylene/propylene/diene copolymer;

- polytetrafluoroethylene, plasticized poly(vinyl chloride), and ethylene/vinyl acetate copolymer;

- thermoplastic elastomers and polyurethane.

NOTE 2 The measurement of dynamic properties of materials with different ranges of moduli can be made using alternative modes of deformation (i.e. a shear mode for 0,1 MPa less than E′ less than 50 MPa, a tensile mode for 0,01 GPa less than E' less than 5 GPa, a torsional mode for 10 MPa less than E′ less than 10 GPa, and flexural modes for E′ greater than 5 GPa.

This method is particularly suited to the measurements of dynamic moduli and loss factors of semi-rigid plastics in the shape of a right-angled prism, cylinder or tube and can be conveniently used to study the variation of dynamic properties with temperature and frequency through most of the glass-rubber relaxation region (see ISO 6721-1:2001, Subclause 9.4). 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 present dynamic properties over an extended frequency range at different temperatures.