Monthly Archives: October 2014

Acronym! Acronym! What are DMA, DMTA, and TMA?

For people who are new to thermal analysis, especially to “mechanical” analysis, the terms DMA, DMTA, TMA can be very confusing.  I mention this because I was confused when I was learning thermal analysis.  Now I pay special attention and ask for clarification when people ask me questions about DMA.  The reason these terms are confusing is because these abbreviations have overlapping and multiple meanings.

First, let’s tackle the most confusing and the most general term, DMA. DMA can mean “dynamic mechanical analysis”; or, DMA can also mean “dynamic mechanical analyzer”.

When it is “dynamic mechanical analyzer”, it refers to the actual machine, the analyzer, itself.  Most instrumentation vendors who sell DMA machines have their DMA model names starting with “DMA”, for example, TA Instruments’ “DMA Q800” and MT’s “DMA 1”.  These DMA machines are usually designed where the sample deformation occurs in the “flex” or “tension” mode, i.e., normal to the sample.

When the acronym DMA is used to refer to “dynamic mechanical analysis”, however, it implies to the analytical methodology where mechanical measurement of the sample is utilized to obtain information we are interested about the sample.  For example, ASTM E1640 “Standard Test Method for Assignment of the Glass Transition Temperatures by Dynamic Mechanical Analysis” describes various modes of DMA such as flexure, torsion, tension, compression, etc.

Similar to DMA, the acronym DMTA means “dynamic mechanical thermal analysis” or, “dynamic mechanical thermal analyzer”.

It is basically the same as DMA except the “T” referring to thermal is inserted into the acronym. Not too many people refer to DMTA nowadays.  It is used almost exclusively referring to the Polymer Laboratory and Rheometric Scientific’s DMA machines since that’s how they name their DMA models.  But since both companies no longer exist nor making DMA machines, this term is not used widely anymore.

Lastly, the acronym TMA refers to “thermo-mechanical analyzer” or “thermo-mechanical analysis”.  TMA refers to the mode of mechanical analysis where a constant load (in stress or strain) is applied to the sample instead of an oscillating load as in the case of the “dynamic” modes.