Dynamic mechanical analyzers (DMA / DMTA) are used for material analysis, particularly to determine the viscoelastic behavior of polymers. Viscoelastic materials are those whose properties fall somewhere between those of elastic and viscous materials; examples of viscoelastic materials in nature include wood, some metals, and human tissue such as ligaments and tendons. Viscoelastic materials have useful applications such as their ability to dampen noise and absorb shock. Dynamic mechanical analyzers can also determine a material’s glass transition temperature, this is the temperature after which a material will change from a ‘glassy’ state to a ‘rubbery’ one.
Dynamic mechanical analyzers work by applying stress to a material in the form of a sinusoidal oscillation. The resultant stress is measured allowing the complex modulus (the ratio of stress to strain) to be determined. The complex modulus of a viscoelastic material will be somewhere between that of a perfectly elastic or viscous material.