Rheology

[Raphaelmartinez]

First of all, thank you all for any help you can provide me. I am an organic chemist, so my understanding of rheology is VERY basic. I have two polymers with similar molecular weight and structure, but with different branching density. All i do in the rheology instrument (Ares G1) is to take viscosity vs shear rate and I try to find the viscosity a low shear rate, plus the behavior as the shear rate increases. One of them is like a Newtonian fluid and the other is not. All i want to do is compare this two polymers, since the only difference is the density branching. I feel that since I am sitting is such as powerful instrument I should take more data. Like a frequency sweep, or temperature ramp to find G' and G" and compare between them. However, I do not know if this could be useful for me or not. I know how to run those experiments, but I do not know what exactly I would be looking at. Should I run an experiment to find G? Will the frequency of the G' and G" crossing point be different and that could tell me something about the polymers? What values can I compare? Should I run a different experiment that help me to compare these two polymers? I know that my questions are very basic, but I the rheology course will not start until the fall and all I find online is heavy math and models, but nothing that help me to answer my questions. Any help is highly appreciate.

 

[Latexman]

If it's up to you, why not take more data? You will definitely learn something new. So, pull back the foreskin of technology, and plunge in!

Good luck,
Latexman

Need help writing a question or understanding a reply? forum1529

 

[Raphaelmartinez]

Can anyway please be more specific about what data can I obtain and/or compare?
Thanks for the help

 

[Latexman]

G' - Elastic (storage) Modulus. A measure of elasticity of the material. The ability of the material to store energy.

G" - Viscous (loss) Modulus. The ability of the material to dissipate energy. Energy is lost as heat.

Tan([σ]) = G"/G' is a measure of the dampening ability of a material, like vibration or sound.

Good luck,
Latexman

Need help writing a question or understanding a reply? forum1529

 

[chicopee]

"...However, I do not know if this could be useful for me or not..." It seems as you are fishing for something and I am not sure what it is. I used to do rheology studies with PVC formulation that entail resins, plasticizers, stabilizers, etc... but these studies were for comparison purposes and manufacturing reasons, so in your case, your evaluation of your rheology tests should be based on certain objectives which you did not state in your OP. What are the objectives of your studies? As far a sampling procedures for statistical evaluation, two numbers pop in my mind, 25 and 50 depending on the type of distribution, however, I would have to recheck my references.

 

[Tipp2239]

Look up polymers and assess all the specifications, data, properties a polymer can give, then go for what are essential to your project.