【国外标准】 Standard Test Method for Assignment of the Glass Transition Temperature By Dynamic Mechanical Analysis

5.1 This test method can be used to locate the glass transition region and assign a glass transition temperature of amorphous and semi-crystalline materials.5.2 Dynamic mechanical analyzers monitor changes in the viscoelastic properties of a material as a function of temperature and frequency, providing a means to quantify these changes. In ideal cases, the temperature of the onset of the decrease in storage modulus marks the glass transition.5.3 The glass transition takes place over a temperature range. This method assigns a single temperature (Tg) to represent that temperature range as measured by dynamic mechanical analysis. Tg may be determined by a variety of techniques and may vary according to that technique.5.4 A glass transition temperature (Tg) is useful in characterizing many important physical attributes of thermoplastic, thermosets, and semi-crystalline materials including their thermal history, processing conditions, physical stability, progress of chemical reactions, degree of cure, and both mechanical and electrical behavior.5.5 This test method is useful for quality control, specification acceptance, and research.1.1 This test method covers the assignment of a glass transition temperature (Tg) of materials using dynamic mechanical analyzers.1.2 This test method is applicable to thermoplastic polymers, thermoset polymers, and partially crystalline materials which are thermally stable in the glass transition region.1.3 The applicable range of temperatures for this test method is dependent upon the instrumentation used, but, in order to encompass all materials, the minimum temperature should be about −150 °C.1.4 This test method is intended for materials having an elastic modulus in the range of 0.5 MPa to 100 GPa.1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.6 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.1.7 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.