Storage modulus is greater than loss

Why is loss modulus higher than storage modulus?

When the experiment is run at higher frequencies, the storage modulus is higher. The material appears to be stiffer. In contrast, the loss modulus is lower at those high frequencies; the material behaves much less like a viscous liquid. In particular, the sharp drop in loss modulus is related to the relaxation time of the material.

What is a storage modulus?

The storage modulus is a measure of how much energy must be put into the sample in order to distort it. The difference between the loading and unloading curves is called the loss modulus, E ". It measures energy lost during that cycling strain. Why would energy be lost in this experiment? In a polymer, it has to do chiefly with chain flow.

What is the'sum' of loss and storage modulus?

The ‘sum’ of loss and storage modulus is the so-called complex modulus G*. The complex viscosity h* is a most usual parameter and can be calculated directly from the complex modulus. This viscosity can be related to the viscosity measured in a steady shear test by a relation known as the Cox-Merz rule.

Why is a complex modulus higher than a storage modulus?

In both cases the complex modulus would be higher, as a result of the greater elastic or viscous contributions. The contributions are not just straight addition, but vector contributions, the angle between the complex modulus and the storage modulus is known as the ‘phase angle’.

What is the difference between loss modulus and complex modulus?

The loss modulus represents the viscous part or the amount of energy dissipated in the sample. The ‘sum’ of loss and storage modulus is the so-called complex modulus G*. The complex viscosity h* is a most usual parameter and can be calculated directly from the complex modulus.

Why does storage modulus increase with frequency?

At a very low frequency, the rate of shear is very low, hence for low frequency the capacity of retaining the original strength of media is high. As the frequency increases the rate of shear also increases, which also increases the amount of energy input to the polymer chains. Therefore storage modulus increases with frequency.