【国外标准】 Standard Test Method for Plastics: Dynamic Mechanical Properties: In Torsion

5.1 This test method provides a simple means of characterizing the thermomechanical behavior of plastics material. The data obtained may be used for quality control, research and development, and establishment of optimum processing conditions.5.2 Dynamic mechanical testing provides a sensitive method for determining thermomechanical characteristics by measuring the elastic and loss moduli as a function of frequency, temperature, or time. Plots of moduli and tan delta of a material versus temperature provide graphical representations indicative of physical and mechanical properties, effectiveness of cure (thermosetting resin system), and damping behavior under specified conditions.5.3 This test method can be used to assess5.3.1 The modulus as a function of temperature,5.3.2 The modulus as a function of frequency,5.3.3 The effects of processing treatment, including orientation,5.3.4 Relative resin behavioral properties, including cure and damping,5.3.5 The effects of substrate types and orientation (fabrication) on elastic modulus, and5.3.6 The effects of formulation additives that might affect processability or performance.5.4 Before proceeding with this test method, reference should be made to the specification of the material being tested. Any test specimen preparation, conditioning, dimensions, or testing parameters, or combination thereof, covered in the relevant ASTM materials specification shall take precedence over those mentioned in this test method. If there are no relevant ASTM materials specifications, then the default conditions apply.1.1 This test method covers the use of dynamic mechanical instrumentation for gathering and reporting the viscoelastic properties of thermoplastic and thermosetting resins and composite systems in the form of rectangular specimens molded directly or cut from sheets, plates, or molded shapes. The torsional data generated may be used to identify the thermomechanical properties of a plastics material or composition.1.2 This test method is intended to provide means for determining the torsional modulus of plastics as a function of temperature using nonresonant forced-vibration techniques, as outlined in Practice D4065. Plots of the elastic (storage), loss (viscous), and complex moduli and tan delta, as a function of frequency, time, or temperature are indicative of significant transitions in the thermomechanical performance of the polymeric material system.1.3 This test method is valid for a wide range of frequencies, typically from 0.01 to 100 Hz.1.4 Apparent discrepancies may arise in results obtained under differing experimental conditions. These apparent differences from results observed in another study can usually be reconciled without changing the observed data by reporting in full (as described in this test method) the conditions under which the data were obtained.1.5 Test data obtained by this test method are relevant and appropriate for use in engineering design.1.6 The values stated in SI units are to be regarded as standard.1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.NOTE 1: This test method is equivalent to ISO 6721, Part 7.1.8 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.