
related topics 
{math, energy, light} 
{acid, form, water} 
{system, computer, user} 

Dynamic Mechanical Analysis (abbreviated DMA, also known as Dynamic Mechanical Spectroscopy) is a technique used to study and characterize materials. It is most useful for studying the viscoelastic behavior of polymers. A sinusoidal stress is applied and the strain in the material is measured, allowing one to determine the complex modulus. The temperature of the sample or the frequency of the stress are often varied, leading to variations in the complex modulus; this approach can be used to locate the glass transition temperature of the material, as well as to identify transitions corresponding to other molecular motions.
Contents
The Theory Behind DMA
Viscoelastic properties of materials
Polymers composed of long molecular chains have unique viscoelastic properties, which combine the characteristics of elastic solids and Newtonian fluids. The classical theory of elasticity describes the mechanical properties of elastic solids where stress is proportional to strain in small deformations. Such response of stress is independent of strain rate. The classical theory of hydrodynamics describes the properties of viscous fluid, for which the response of stress is dependent on strain rate.^{[1]} This solidlike and liquidlike behavior of polymer can be modeled mechanically with combinations of springs and dashpots.^{[2]}
Full article ▸


related documents 
Maunder Minimum 
Miranda (moon) 
Ring current 
Strouhal number 
Fomalhaut 
Nova 
Frustum 
3753 Cruithne 
Weyl's postulate 
North Star 
Wide angle Xray scattering 
Superluminal communication 
Spheroid 
Archimedean spiral 
Solar furnace 
Iapetus (moon) 
Atomic, molecular, and optical physics 
Pascal (pressure) 
Ohmmeter 
Quantum leap 
Angular acceleration 
Antenna effective area 
Gegenschein 
Coulomb 
Fundamental frequency 
General Conference on Weights and Measures 
Equatorial coordinate system 
Transmission medium 
Speed 
Csymmetry 
