How to predict temperature dependent Young's modulus of polymer and polymer composites? Are there some classic and effective prediction methods?
How to theoretically describe the viscoelastic behavior of polymer and polymer composites at elevated temperatures and provide the corresponding Young's modulus at different temperatures？
I don't know of a classical method that meets your needs. For my part, I have answered the questions you ask by using an equation of state and by developing original experimental means to measure all the useful parameters. This approach has extremely varied technological applications. The documents that describe it are too large to be downloaded. They will be available online. If you are interested I will send you the link of the site in English which is under development.
Regards
To predict the young’s modulus of a viscoelastic polymer at elevated temperatures you can use the TTSP (Time-Temperature-Superposition Principle) in combination with the classical theory of linear viscoelasticity. For a sufficient characterization you will need DMA (Dynamic Mechanical Analysis) measurements at different temperatures (RT and higher) and frequencies (typical 0.1-100 Hz). After creating a master curve at your temperature using WLF or Arrhenius you can shift this curve to the temperature of interest (if you have enough measurement data). In terms of theory check: Hal F.Brinson, Polymer Engineering Science and Viscoelasticity, Chapter 7, https://doi.org/10.1007/978-1-4899-7485-3; and N.W. Tschoegl, The Effect of Temperature and Pressure on the Mechanical Properties of Thermo- and/or Piezorheologically Simple Polymeric Materials in Thermodynamic Equilibrium – A Critical Review. Article The Effect of Temperature and Pressure on the Mechanical Pro...
With respect to composite it depends how complicated your model should be? If you want to make an easy first guess to estimate the upper and lower bound you can use the Voigt and Reuse model. It is simply the rule of mixture assuming one same strain and one time same stress. There is a book from M. Ashby which should help you with this: Materials Selection in Mechanical Design, Chapter 12. Designing Hybrid Materials, https://doi.org/10.1016/C2009-0-25539-5
You shall consider the nanoreinforcement effect in nanocomposites.
Article Effect of Nanoparticle Organization on Molecular Mobility an...
It comes from the nanoconfinement and has two contributions, the closest-neighbor caging and the longer-range distortion.
Article Nature of dynamic gradients, glass formation, and collective...
Naturally, the effect is the strongest in unconfined polymers with sufficient mobility - that is above Tg (PE, PP, rubbers, etc.).
How to predict temperature dependent Young's modulus of polymer and polymer composites?
Hello,
We need to measure the variation in internal energy and the density of defects responsible for stress reinforcement and the elastoplastic energy transformation process. The temperature depends on the kinetics of the transformation. Theoretically, this is described by an equation of state. Experimentally, shock generation methods are difficult to use and rarely allow measurement of the parameters of this equation. We use a method that produces the internal shocks that are directly responsible for the decrease in Young's modulus and the increase in permittivity. This transformation exists in all materials, and to predict their aging and destruction we need to use the parameters of an equation of state. Models based on Griffith's principle and the computational techniques of continuum mechanics can reproduce experimental curves, but are based on assumptions that are contradicted by reality, and cannot be applied from one material to another. There are other simple ways of doing things, without unverifiable hypotheses and strictly based on the principles of physical chemistry.
Have a nice day.
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