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Definitions of Dynamic Mechanical Analysis (DMA) |
• A technique in which the sample's kinetic properties are analyzed by measuring the strain or stress that is generated as a result of strain or stress, varies (oscillate) with time, applied to the sample.
• Static Viscoelasticity Measurement
A technique in which the change in stress or strain is measured under uniform stress or strain that remains constant across time. |
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These are definitions of DMA by JIS
[Description of DMA]
Figure 1. Block diagram of DMA (Tension mode)
Figure 1 shows the Block diagram of DMA.
The sample is clamped into a frame of measurement head and is heated by the furnace. The sample in the furnace is applied the stress from the force generator via probe. To make the strain amplitude constant, the stress is applied as the sinusoidal force. This frequency is one of the measurement conditions. The deformation amount generated by the sinusoidal force is detected. Viscoelastic values such as elasticity and viscosity is calculated from the applied stress and the strain and plotted as a function of temperature or time.
Figure 2. DMA Deformation modes
DMA can be applied to a wide range of materials using the different deformation modes. DMA deformation mode has tension, compression, dual cantilever bending, 3-point bending, and shear mode. The deformation mode is selected dependent on the specimen shape and modulus, and the measurement purpose.
As viscoelastic properties, storage modulus: E', G' (purely elastic component), loss modulus: E", G" (purely viscous component), loss tangent: tanδ (=E"/E'), etc temperature dependence and frequency dependence can be measured by DMA.
The analysis of the glass transition temperature and temperature dependence of the modulus can be measured by the temperature dispersion measurement. By performing the simultaneous measurement of temperature dispersion and frequency dispersion measurement, relaxation phenomena including glass transition can be observed. It enables to obtain the information of molecular structure and molecular motion of polymer.
Description of other analysis method:
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