Measurement Parameter
Numerical representation of the energy dissipated as heat when a material is deformed. The loss modulus describes the viscous response of a polymer or composite under cyclic stress. It is a critical parameter for understanding the damping characteristics of electronic encapsulants and adhesives.
Dynamic Response
Testing involves applying a sinusoidal force and measuring the phase lag of the resulting strain. In materials with a high loss modulus, a measurable portion of the mechanical energy is lost to internal friction. This property is measured using dynamic mechanical analysis.
The results are expressed in units of pressure such as Pascals.
Frequency Influence
Molecular relaxation times determine how the material responds to different speeds of loading. The loss modulus varies with the frequency of the vibration and the ambient temperature. At the glass transition temperature, the loss modulus typically reaches a maximum as the polymer chains gain mobility.
This information is used to design products that can withstand mechanical shock.
Material Selection
Polymers are selected based on their ability to absorb energy and reduce resonances. A high loss modulus in a potting compound can help to protect sensitive components from high frequency vibrations. Designers compare the loss modulus to the storage modulus to determine the overall damping factor.
This ensures the mechanical stability of the assembly.