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
Tiny UAVs and hummingbirds are put to test
Britain to trial driverless cars from 2015
NIST corrosion lab tests suggest need for underground gas tank retrofits
Chestermiller
#2
May28-14, 07:24 PM
Sci Advisor
HW Helper
Thanks
PF Gold
Chestermiller's Avatar
P: 5,064
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