Thermomechanical analysis

Introduction and definition of thermal analysis techniques

Thermomechanical analysis (TMA) is one of a group of techniques termed thermal analysis (TA). The terminology of thermal analysis is recommended by the International Confederation of Thermal Analysis and Calorimetry (ICTAC). Terminologies have been redefined to provide consistency amongst the numerous thermal analysis techniques (1). In particular TMA has been classified as a method of the thermomechanometry (TM) technique.

Thermomechanometry is the measurement of a change of a dimension or a mechanical property of the sample while it is subjected to a temperature regime. An associated thermoanalytical method is thermomechanical analysis. A special related technique is thermodilatometry (TD), the measurement of a change of a dimension of the sample with a negligible force acting on the sample while it is subjected to a temperature regime. The associated thermoanalytical method is thermodilatometric analysis (TDA). TDA is often referred to as zero force TMA. The temperature regime may be heating, cooling at a rate of temperature change that can include stepwise temperature changes, linear rate of change, temperature modulation with a set frequency and amplitude, free (uncontrolled) heating or cooling, or holding the temperature constant. The sequence of temperatures with respect to time may be predetermined (temperature programmed) or sample controlled (controlled by a feedback signal from the sample response).Thermomechanometry includes several variations according to the force and the way the force is applied. Static force TM (sf-TM) is when the applied force is constant; previously called TMA with TD as the special case of zero force. Dynamic force TM (df-TM) is when the force is changed as for the case of a typical stress–strain analysis; previously called TMA with the term dynamic meaning any alteration of the variable with time, and not to be confused with dynamic mechanical analysis (DMA). Modulated force TM (mf-TM) is when the force is changed with a frequency and amplitude; previously called DMA. The term modulated is a special variant of dynamic, used to be consistent with modulated temperature differential scanning calorimetry (mt-DSC) and other situations when a variable is imposed in a cyclic manner (2).