Well, it clearly indicates the sample is soild-like. In my experiments also I noticed and if you work with liquid-like polymers like DMS or PEG you could fine G'' is more systematic than G'.

Thanks jasmin. But why is that g' or g'' goes fluctuating?? 

It's material property. Since, G' is dominating say few log scales so the change in G'' is almost insignificant. If you take a true viscoelastic fluid you can see both systematic.

Agreed. The G' and G'' values are in fact results of Fourier transform of the raw signal (stress or displacement). When one of the values dominate, the accuracy of determination of another one gets poorer. As a rule of thumb, when the lower modulus is below1% of the higher one (this gives two order of magnitude difference), the lower modulus cannot be measured accurately.

Agreed to above comments. Dominating behavior (G') could affect sensitivity of the other behavior (G") which of significantly lower order. However, It is worth checking with data sheet, if there is no error signal for any of the data. G" is generally more sensitive to material structure and is more prone to variation from batch to batch.     

Below the yield stress the gel behaves like an elastic solid with a proportionality between shear strain and shear stress. Hence, the phase shift between shear strain and shear stress is in the vicinity of 0 (and may be very defective). The  cosine function in G'  is nearly 1 whereas the sine function in G'' fluctuates with the phase shift. Hence, small errors in the phase shift lead to fluctuations in G'' and G' remains more or less uneffeted.

Hi Abhinav, 

I agree with most of the comments above.  One more point I wanted to bring to the table is you are working with gels, so the cross link density also affects your experiment.  There are other factors also comes to play, such as if these gel samples have residual trapped solvent in the mix. Hope this helps,

Best wishes, 

Mayur.