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Lithium ion-conducting plasticized polymer electrolyte membranes were prepared using poly (vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) as the host polymer, lithium triflate (LiTf) as the dopant salt, and ethylene carbonate (EC) as the plasticizer, with varying compositions accomplished using the solution casting technique. X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and differential scanning calorimetry (DSC) analyses validate the presence of substantial structural alterations and the formation of a complex in the plasticized polymer electrolytes. The electrochemical impedance spectroscopy (EIS) analysis demonstrates an increase in ionic conductivity by about two orders of magnitude after the addition of EC. Estimates of ionic transference numbers derived from the direct current (DC) polarization approach indicate that charge transport in plasticized polymer electrolytes is mostly ionic. We examined the discharge characteristics of our flexible electrochemical storage device (FESD) over 25 h. The mean discharge current is 1.4 mA with a 0.04 C rating.

The self-diffusion coefficient of the cyclohexane in some polybutadiene solutions was measured by NMR pulse magnetic field gradient method. The experimental data were analyzed on the basis of the free volume theory. A specific algorithm for analyze was proposed. Preliminary investigation indicates a deviation from the WLF theory for these solutions.

Results of molecular motion studies carried out in two liquid crystal forming compounds n-p-cyano-p-hexyloxybiphenyl (M18) and n-p-ethoxybenzylidene-p-butylaniline (EBBA) using positron lifetime spectroscopy (PLS) are presented. Temperature dependent positron lifetime measurements have been performed in each compound during the heating cycle of samples prepared by either quenching or slow cooling from the respective liquid crystalline phase of the compounds. In both the compounds, behaviors of the quenched and slow cooled samples are found to be different. The material in the quenched sample, unlike the slow-cooled sample, exhibits strong temperature dependence before it undergoes a glass transition. In each case, the temperature dependence of o-Ps pick-off lifetime in the quenched sample shows broad peaks at various characteristic temperatures. These peaks have been attributed to various intra- and inter-molecular motions associated with these compounds. The characteristic frequencies of some of the modes observed in the present work agree well with the literature reported values obtained from FIR and Raman studies. The present study demonstrates the usefulness of PLS in the study of molecular motions.

The glass transition temperature (Tg) in the amorphous region of an insulation paper is one of the most important characteristics for thermal stability. Molecular dynamic simulations have been performed on three micro-structural models, namely, amorphous pure cellulose, amorphous cellulose with water and amorphous cellulose with oil, to study the microscopic mechanism of the glass transition process for oil-immersed transformer insulation paper. Using the method of specific volume versus temperature curve, the Tg of amorphous pure cellulose, cellulose with water, and cellulose with oil was determined as 448, 418 and 440 K, respectively. The current study may provide some information for thermal aging. The simulation results show that during the glass transition process, both the chain motion and mechanical properties of cellulose changes significantly. Relative to the oil molecules, water molecules immersed in the amorphous region of insulation paper can disrupt hydrogen bonds between cellulose chains. This phenomenon results in a significant reduction in the glass transition temperature and affects the thermal stability of the insulation paper.

Bulk metallic glasses are often used well below their glass transition temperatures, T_g, because of their change in the physical properties of the material through its glass transition, which is not considered a phase transition; rather it is a phenomenon extending over a range of temperature and is defined by a viscosity threshold of 10¹² Pa ⋅ s. In this work, a Zr-based metallic glass upon annealing below glass transition temperature (T_g–30 K) was quasi-in-situ investigated. The structural and elastic properties were observed carefully by utilizing an in-house designed density testing device and an ultrasonic testing device. We found out that the density, the shear velocity, the longitudinal wave velocity, and the elastic modulus increased through annealing at 719 K for 300, 900 and 1500 s. A possible explanation was presented based on the free volume theory and it was found that the relaxation kinetics in this study obeyed the Kohlraush–Williams–Watts (KWW) relaxation function with $\beta$ = 0.420 $<$ 1 implying that the relaxation mechanisms were multiple ones.

A molecular dynamics simulation was conducted with the aid of Materials Studio (MS6.0) software platform at different temperature conditions to study the diffusion processes of oxygen gas molecules in the 32% EVOH membrane. The mean square displacement, radial distribution function and free volume at different temperature in 32% EVOH membrane are obtained, respectively. Results showed that the diffusion coefficient of oxygen, radial distribution function of –OH on the molecular chain in 32% EVOH membrane and free volume of cell in 32% EVOH membrane increased with the increase of temperature.

A molecular dynamics simulation was conducted with the aid of Materials Studio 6.0(MS6.0) software platform under different relative humidity conditions to study the diffusion processes of oxygen gas molecules in the 32% high barrier EVOH membrane. The mean square displacement, radial distribution function and free volume of different relative humidity in 32% EVOH membrane were obtained, respectively. Results showed that the diffusion coefficient of oxygen gas molecules and free volume of amorphous cell construction in 32% EVOH membrane increase with the increase of relative humidity. Radial distribution function of –OH on the molecular chain of 32% EVOH decreased with the increase of relative humidity. It indicated that for food reservation application of EVOH, it was necessary to keep dry condition.

The following sections are included:

• Gibbs’ Statistical Mechanics for Small Systems
• One Particle at a Time – The Cell Model for Hard Disks
• Cell Model, Free Volume, and Percolation Transition
  • Free Volume
  • Microscopic Free Volumes – Percolation Transition
• Molecular Dynamics for Hard Disks from 1962 to 2013
• The Galton Board, a Simple Nonequilibrium System
• Fractal Dimensions of the Galton Board Distributions
• The Galton Staircase
• Oscillator Heat Conduction with a Thermal Gradient
  • The Mexican Hat Potential as a Small System
• The Conservative and Dissipative Baker Maps
• Summary of Lecture 7
• References