Dynamic Mechanical Analysis (DMA)

Dynamic Mechanical Analysis (DMA) is an indispensable tool for determining the visco-elastic properties of materials, mainly polymers. Elastomers, for example, are very rigid below the glass transition temperature (Tg) and have a high modulus of elasticity. Above Tg, they are flexible and show damping performance. DMA measures the visco-elastic properties during a controlled temperature and/or frequency program.

How Do Visco-Elastic Polymers Behave?

The dynamic-mechanical properties of visco-elastic polymer materials are dependent on the operating temperature, the type of oscillating force applied to the sample in a defined deformation mode and the frequency or time of the applied oscillating force. The determined modulus of elasticity of a polymer material is not a constant number, but a function of the temperature, time and frequency of the dynamic force applied to a specimen with a defined geometry.

Method

During the test, a sinusoidal force (stress σ) is applied to the sample (input). This results in a sinusoidal deformation (strain ε; output).

Certain materials, such as polymers, exhibit viscoelastic behavior; i.e., they have both elastic properties (such as an ideal spring) and viscous ones (such as an ideal dashpot). This viscoelastic behavior causes shifting of the corresponding stress and strain curves. The deviation is referred to as the phase shift δ. The response signal (strain, ε) is split into an “in-phase” and an “out-of-phase” part by means of Fourier Transformation.

The method is described in, for example, ISO 6721-1 to 12, ASTM D4065-90, ASTM D4092-90, ASTM D4473-95, ASTM D5418-99, ASTM D5023-99, ASTM D5024-95a, ASTM D5026-95a, ASTM D5279-99, ASTM E1640-94 and ASTM E1867-97.

Which Materials Can Be Tested?

From viscous liquids, rubber to fiber-reinforced plastics, from food and pharmaceuticals to metals and ceramics – all such materials can be analyzed with DMA by using different sample holders, accessories and measurement modes.

Deformation Modes

  • 3-point bending
  • 4-point bending
  • Single/dual cantilever bending
  • Tension
  • Shear
  • Compression
  • Penetration

Measurement Modes

  • Static Modes: TMA, iso-strain, creep and relaxation
  • Dynamic Modes: Standard, stress and strain-sweep
  • Multi-Frequency Tests
  • Immersion Tests

Parameters Obtained by DMA

Information Resulting from DMA Measurements

  • Design data concerning stiffness and damping properties (modulus values and damping factor under a variety of conditions)
  • Data on the composition and structure of polymer blends (compatibility)
  • Glass transition temperature Tg of highly cross-linked, amorphous or semi-crystalline polymers and composites
  • Curing/post-curing
  • Aging
  • Prediction of the material behavior using Time-Temperature-Superposition (TTS)

NETZSCH DMA Systems

DMA 242 E Artemis

The robust construction of the DMA 242 E Artemis and the high resolution of the deformation measuring system enable precise measurements on both very rigid and very soft samples. The most varied of deformation types, digital signal filtering, kinetic evaluation and frequency extrapolation make the DMA 242 E Artemis to a real all-rounder in the force range up to 24 N.

DiPLEXOR®

Simultaneous Dielectric (DEA) and Dynamic Mechanical Analyzer (DMA)

DMA GABO EPLEXOR® Series up to 500 N

The testing instruments of the DMA GABO EPLEXOR® series up to ±500 N enable the dynamic mechanical (or static) characterization of a wide range of different materials including elastomers and polymers, composites, metals, glasses, ceramics, biomaterials and foods, adhesives, and liquids.

DMA GABO EPLEXOR® Ultra-High Force Series up to 6000 N

The floor-standing, modular, high-end NETZSCH DMA GABO EPLEXOR® series is specifically designed to determine the linear and non-linear viscoelastic behavior of materials which require measurements under very high force levels and/or large deformations.

DMA EPLEXOR® High-Temperature Series up to 500 N

The EPLEXOR® HT series by NETZSCH GABO is the only DMA/DMTA instrument line on market for measurements up to 1500°C.