Register to reply

Viscoelastic properties of hydrogels (DMA)

by neejam
Tags: hydrogels, properties, viscoelastic
Share this thread:
neejam
#1
May25-14, 08:30 AM
P: 1
Hi,

I am a Bachelor Student of biomedical engineering and I have a question regarding the complex compressive modulus. I am really a newbie in this field, hopefully somebody can help me.
I have measured four different hydrogel films to compare with the same conditions using a dynamic mechanical analyzer (DMA, measured in compression mode with a sinusoidal deformation of constant amplitude, ε=0.1%).
Now the results show that the materials that have the highest storage modulus also have the highest tan δ, which is a bit confusing to me as I though when measuring viscoelastic materials with a DMA it should always the other way round (so the ones with the highest E' should have the lowest tan δ). I am attaching E', E'' and tan delta graphs so you see what I mean.
Thank you!



Phys.Org News Partner Engineering news on Phys.org
DIY glove-based tutor indicates muscle-memory potential
Tricorder XPRIZE: 10 teams advance in global competition to develop consumer-focused diagnostic device
Study shows local seismic isolation and damping methods provide optimal protection for essential computing equipment
Chestermiller
#2
May28-14, 07:24 PM
Sci Advisor
HW Helper
Thanks
PF Gold
Chestermiller's Avatar
P: 5,254
The storage modulus is an absolute quantity, and tan δ, the ratio of the loss modulus to the storage modulus is a relative quantity. So it isn't really relevant to compare the storage modulus of a given material to its tan δ . The tan δ in the figures appears to be roughly decreasing with frequency, which is what would be expected.

Chet


Register to reply

Related Discussions
Viscoelastic Behaviour General Physics 1
Viscoelastic Models Materials & Chemical Engineering 1
Viscoelastic Material Properties Mechanical Engineering 0
Need help with FEA of a viscoelastic damper Mechanical Engineering 4
Viscoelastic models Atomic, Solid State, Comp. Physics 2