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The WLF equation is a consequence of time–temperature superposition (TTSP), which mathematically is an application of Boltzmann's superposition principle. It is TTSP, not WLF, that allows the assembly of a compliance master curve that spans more time, or frequency, than afforded by the time available for experimentation or the frequency range ...
The WLF model is related to macroscopic motion of the bulk material, while the Arrhenius model considers local motion of polymer chains. Some materials, polymers in particular, show a strong dependence of viscoelastic properties on the temperature at which they are measured.
Flory–Huggins solution theory is a lattice model of the thermodynamics of polymer solutions which takes account of the great dissimilarity in molecular sizes in adapting the usual expression for the entropy of mixing. The result is an equation for the Gibbs free energy change for mixing a polymer with a solvent. Although it makes simplifying ...
The kinetic theory of gases allows accurate calculation of the temperature-variation of gaseous viscosity. The theoretical basis of the kinetic theory is given by the Boltzmann equation and Chapman–Enskog theory, which allow accurate statistical modeling of molecular trajectories.
In this equation is the attraction from the osmotic effect. ∂ f ∂ a {\displaystyle {\frac {\partial f}{\partial a}}} is the repulsion due to chain molecules confined between plates. p {\displaystyle p} is on order of r {\displaystyle \langle r\rangle } , the mean end-to-end distance of chain molecules in free space.
where is the polymer's characteristic persistence length, is the Boltzmann constant, and is the absolute temperature. At finite temperatures, the end-to end distance of the polymer will be significantly shorter than the maximum length . This is caused by thermal fluctuations, which result in a coiled, random configuration of the undisturbed ...
En Honduras, la rama del Banco Mundial que presta al sector privado financió a una compañía clave en una disputa sobre derechos de tierras que ha acabado con la vida de más de 130 personas, incluido Gregorio Chávez, un predicador que un día salió a trabajar en su huerto y nunca volvió a casa. En la última década, los préstamos de la Corporación Financiera Internacional y su ...
The phase behavior of polymer solutions is an important property involved in the development and design of most polymer-related processes. Partially miscible polymer solutions often exhibit two solubility boundaries, the upper critical solution temperature (UCST) and the LCST, both of which depend on the molar mass and the pressure. At ...