From Polymer Reference Book

15.1 Dynamic Mechanical Analysis

15.1.1 Theory

Dynamic mechanical analysis (DMA) provides putative information on the viscoelastic properties - modulus and damping - of materials. Viscoelasticity is the characteristic behaviour of most materials in which a combination of elastic properties (stress proportional to strain rate) are observed. A DMA simultaneously measures both elastic properties (modulus) and viscous properties (damping) of a material.

DMA measures changes in mechanical behaviour such as modulus and damping as a function of temperature, time, frequency, stress, or combinations of these parameters.

The technique also measures the modulus (stiffness) and damping (energy dissipation) properties of materials as they are deformed under periodic stress. Such measurements provide quantitative and qualitative information about the performance of the materials. The technique can be used to evaluate elastomers, viscous thermoset liquids, composite coatings, and adhesives, and materials that exhibit time, frequency, and temperature effects or mechanical properties because of their viscoelastic behaviour.

Some of the viscoelastic and rheological properties of polymers that can be measured by DMA are [1, 2]:

  • Modulus and strength (elastic properties)

  • Viscosity (stress strain rate)

  • Damping characteristics

  • Low- and high-temperature behaviour (stress strain)

  • Viscoelastic behaviour

  • Compliance

  • Stress relaxation and stress relaxation modulus

  • Creep

  • Gelation

  • Projection of material behaviour

  • Polymer lifetime prediction

Basically this technique involves the measurement of the mechanical response of a polymer as it is deformed under periodic stress and is used to characterise the viscoelastic and rheological properties of polymers.

DMA is the measurement of the mechanical response of a material as it is deformed under...

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Calorimeters and Thermal Analyzers
Calorimeters and thermal analyzers contain a heat source that can deliver a heat flux, at a distinct temperature, into a sample, and a temperature-measuring device that can read the resultant change in temperature.
Polymers and Plastic Resins
Polymers and plastic materials are organic, synthetic or processed polymers that are supplied as raw materials. They typically consist of thermoplastic or thermosetting resins in the form of pellets, powders or liquid resins. These materials can then be molded into a variety of shapes for a wide range of uses.
Elastomers and Rubber Compounds
Elastomers and rubber materials are characterized by their high degree of flexibility and elasticity (high reversible elongation or resilience).
Strain Gauges
Strain gauges are measuring elements that convert force, pressure, tension, etc., into an electrical signal.
Gel Elastomers
Gel elastomers are highly viscoelastic polymer gel materials that have excellent shock absorption and damping characteristics. They are available in a variety of material types and grades.

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