【国外标准】 Standard Test Method for Assignment of a Glass Transition Temperature Using Thermomechanical Analysis: Tension Method

5.1 The glass transition is dependent on the thermal history, softening agents or additives of the material to be tested. For amorphous and semicrystalline materials the assignment of a glass transition temperature may lead to important information about thermal history, processing conditions, stability, progress of chemical reactions, and mechanical and electrical behavior.5.2 Thermomechanical analysis provides a rapid means of detecting changes in hardness or linear dimensional change associated with the glass transition. Dimensional changes measured as a specimen is heated over the glass transition region may include the interaction of several effects: an increase in the coefficient of expansion, a decrease in the modulus, which under a constant stress leads to increased extension, stress relief leading to irreversible dimensional change (shrinkage in one dimension, expansion in another dimension), and physical aging effects which change the kinetics of the dimensional change.5.3 This test method is useful for research and development, quality control, and specification acceptance testing; particularly of films and fibers.1.1 This test method describes a procedure for the assignment of a glass transition temperature (Tg) of materials on heating using thermomechanical measurements in tension.1.2 This test method may be used as a complement to Test Method E1545 and is applicable to amorphous or to partially crystalline materials in the form of films, fibers, wires, etc., that are sufficiently rigid to inhibit extension during loading at ambient temperature.1.3 The generally applicable temperature range for this test method is 25 °C to 600 °C. This temperature range may be altered depending upon the instrumentation used.1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.5 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.1.6 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.