Polymer viscoelasticity and the relaxation modulus

In this video I introduce the relaxation modulus, showing time-dependent stress-relaxation. I also introduce the glass-transition temperature and the melting temperature.

[@rez8o352]

you've proven that not everyone can deliver this kind of information as logical and clear as you just did. you have my gratitude sir

[@manolorios8927]

I’m a PhD student, and you just saved my life.

[@RZ-mo5qb]

awesome explanation fullfilling my PhD course lol

[@sahandsoltanieh5186]

awesome thank you!!

[@parastooaghr]

Thank you veeeeeeeeery much

[@diejer4711]

very informative intro for a rookie, thx.

[@zahramollazadeh9432]

hi . this course was very helpful for me. great job and tnx a lot

[@Boris-sq2us]

This is explained perfectly. Getting ready for my PhD comprehensive exam and this just saved me a ton of time. Thank you.

[@ScottRamsay]

Good luck on your exam!

[@marinacastro1822]

Thank you very much again!

[@RZ-mo5qb]

how ya doing

[@marcowen1506]

nice, clear video.
You say divit, I say divot.

[@HazimEng]

hi
Can you tell me how to fit the strain data of a viscoelastic material obtained from creep test by prony series

[@SuperSlainer]

Thanks for the video 👌
Sigma (t), is this the difference in stress from as soon as the given strain is reached to the point where it no longer changes?

[@nguyenngocvinhxd]

In Abaqus software, the viscoelastic model of material can be defined based on the shear test data of normalized shear compliance j(s) or modulus g(R). Please guide me on the way to calculate j(s) or g(R) from the stress relaxation data.

[@YogeshKumar-tg3uo]

I have the same doubt. Please comment if you have found out

[@furkansalihkuk]

Sir and Dear Friends I have a question. How can we fixed the length ? When we apply force should not we observe elongation ? I think from Stress= Module x Strain. If strain is fixed and stress is decreasing it means modulus of material also changes ? Thank you.

[@marcowen1506]

for a typical stress relaxation, we stretch the sample by a fixed amount and measure the stress needed to keep the sample at that length. You are correct that if strain is constant and stress is decreasing with time, that this implies that the modulus is also a function of time (see relaxation modulus in video, E_r). It is well known that polymers "remember" previous mechanical treatment: a polymer sample that has been strained is less stiff than an unstrained sample. This memory is because polymer properties are time (history) dependent. Properties of polymers are also rate dependent - there is a lot of time dependency in polymer science!

[@kbee225]

They should call it quartzy instead of glassy shouldn't they!