ترغب بنشر مسار تعليمي؟ اضغط هنا

A Perturbation Theory Modification of the Flory-Huggins Polymer Solution Theory

44   0   0.0 ( 0 )
 نشر من قبل G.Ali Mansoori
 تاريخ النشر 2017
  مجال البحث فيزياء
والبحث باللغة English
 تأليف G.A. Mansoori




اسأل ChatGPT حول البحث

A perturbation theory modification of the Flory-Huggins polymer solution theory is presented. The proposed perturbation equation utilizes the results by Tukur et al [J. Chem. Phys. 110 (7), 3463, 1999] for hard-sphere binary mixture at infinite size ratio. The resulting perturbation theory equations are used to predict properties of three different polymers with different molecular weights in different solvents. Comparison of the proposed perturbation calculations with those of the Flory-Huggins theory and the experimental data indicate that the proposed perturbation method appreciably improves prediction of polymer solution properties especially at large polymer / solvent size ratios.

قيم البحث

اقرأ أيضاً

We present micro-rheological measurments of the drag force on colloids pulled through a solution of lambda-DNA (used here as a monodisperse model polymer) with an optical tweezer. The experiments show a violation of the Stokes-Einstein relation based on the independently measured viscosity of the DNA solution: the drag force is larger than expected. We attribute this to the accumulation of DNA infront of the colloid and the reduced DNA density behind the colloid. This hypothesis is corroborated by a simple drift-diffusion model for the DNA molecules, which reproduces the experimental data surprisingly well, as well as by corresponding Brownian dynamics simulations.
214 - C. Dalitz , E.H. de Groot 1997
An explicit solution of the stationary one dimensional half-space boundary value problem for the linear Boltzmann equation is presented in the presence of an arbitrarily high constant external field. The collision kernel is assumed to be separable, w hich is also known as relaxation time approximation; the relaxation time may depend on the electron velocity. Our method consists in a transformation of the half-space problem into a nonnormal singular integral equation, which has an explicit solution.
We develop a theory for polymer translocation driven by a time-dependent force through an oscillating nanopore. To this end, we extend the iso-flux tension propagation theory (IFTP) [Sarabadani textit{et al., J. Chem. Phys.}, 2014, textbf{141}, 21490 7] for such a setup. We assume that the external driving force in the pore has a component oscillating in time, and the flickering pore is similarly described by an oscillating term in the pore friction. In addition to numerically solving the model, we derive analytical approximations that are in good agreement with the numerical simulations. Our results show that by controlling either the force or pore oscillations, the translocation process can be either sped up or slowed down depending on the frequency of the oscillations and the characteristic time scale of the process. We also show that while in the low and high frequency limits the translocation time $tau$ follows the established scaling relation with respect to chain length $N_0$, in the intermediate frequency regime small periodic fluctuations can have drastic effects on the dynamical scaling. The results can be easily generalized for non-periodic oscillations and elucidate the role of time dependent forces and pore oscillations in driven polymer translocation.
We discuss the application of the adiabatic perturbation theory to analyze the dynamics in various systems in the limit of slow parametric changes of the Hamiltonian. We first consider a two-level system and give an elementary derivation of the asymp totics of the transition probability when the tuning parameter slowly changes in the finite range. Then we apply this perturbation theory to many-particle systems with low energy spectrum characterized by quasiparticle excitations. Within this approach we derive the scaling of various quantities such as the density of generated defects, entropy and energy. We discuss the applications of this approach to a specific situation where the system crosses a quantum critical point. We also show the connection between adiabatic and sudden quenches near a quantum phase transitions and discuss the effects of quasiparticle statistics on slow and sudden quenches at finite temperatures.
التعليقات
جاري جلب التعليقات جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا