Polyme Analysis 2010 Part 8 doc

Dynamic Mechanical Analysis DMAüDetermines elastic modulus or storage modulus, G', viscous modulus or loss modulus, G'' and damping coefficient Tan D as a function of temperature, freque

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As received_J3 NaOH_J3

NaOH/(APS+XB)_J3 NaOH/Y9669_J3

Temperature(°C)

TG and DTG curves of jute fibre with different treatments

Dynamic Mechanical Analysis (DMA)

üDetermines elastic modulus (or storage modulus, G'),

viscous modulus (or loss modulus, G'') and damping

coefficient (Tan D) as a function of temperature, frequency

or time

üResults are typically provided as a graphical plot of G', G'', and Tan D versus temperature

üIdentifies transition regions in plastics, such as the glass transition, and may be used for quality control or product development

ü Can recognize small transition regions that are beyond the resolution of DSC (Differential Scanning Calorimetry)

Scope:

-Typically 56 x 13 x 3 mm, cut from the center section of an ASTM Type I tensile bar,

or an ISO multipurpose test specimen.

Specimen size:

Dynamic Mechanical Analysis (DMA)

üThe test specimen is clamped between the movable and stationary fixtures, and then enclosed in the thermal chamber

üFrequency, amplitude, and a temperature range appropriate for the material being tested are input

üThe Analyzer applies torsional oscillation to the test sample while slowly moving through the specified temperature range

Test Procedure:

Is DMA Thermal Analysis or Rheology

Ø Definitions

Ø Thermal Analysis is the measurement of some characteristic of a

substance as a function of temperature or time

Ø Rheology is the science of flow and deformation of matter.

Ø DMA is the general name given to an instrument that mechanically deforms

a sample and measures the sample response The deformation can be

applied sinusoidally, in a constant (or step) fashion, or under a fixed rate

The response to the deformation can be monitored as a function of

temperature or time.

Response

Phase angle δ

l An oscillatory (sinusoidal)

deformation (stress or strain)

is applied to a sample.

lThe material response

(strain or stress) is measured.

lThe phase angle δ , or phase

shift, between the deformation

and response is measured.

Dynamic Mechanical Testing

Strain

Purely Elastic Response

(Hookean Solid)

Purely Viscous Response

(Newtonian Liquid)

Stress

Strain

Dynamic Mechanical Testing

Phase angle 0 < δ < 90

Strain

Stress

Dynamic Mechanical Testing: Viscoelastic Material Response

DMA Viscoelastic Parameters

The Elastic (Storage) Modulus:

Measure of elasticity of material The

ability of the material to store energy G' = (stress/strain)cos δ

G" = (stress/strain)sin δ

The Viscous (loss) Modulus:

The ability of the material to dissipate

energy Energy lost as heat

The Modulus: Measure of materials

overall resistance to deformation G = Stress/Strain

Tan δ = G"/G'

Tan Delta:

Measure of material damping - such

as vibration or sound damping

Storage and Loss of a Viscoelastic Material

SUPER BALL

TENNIS BALL X

STORAGE LOSS