Polymer physical models

The development of water-swellable polymers depends on aspects of their synthesis, properties evaluation, optimization and correlation of these properties with synthesis conditions. Obviously, studying the behavior of SAH in contact with liquid and solid phases of the soil as well as with plants requires developing physical models and algorithms suitable for the prediction of SAH efficiency. 

The topic of molecular motion is an active one in experimental and theoretical polymer physics, and we may expect that in time the simple reptation model will be superseded by more sophisticated models. However, in the form presented here, reptation is likely to remain important as a semi-quantitative model of polymer motion, showing as it does the essential similarity of phenomena which have their origin in the flow of polymer molecules. 

It was obvious that the FJC model did not represent the experimental result well. Thus, nanofishing could be used to judge the ever-present basic theories of polymer physics. 

Narasinham, B Peppas, N, A, The Physics of Polymer Dissolution Modeling Approaches and Experimental Behavior, Vol, 128, pp. 157-208,... 

AA Kefeli. Reactions of Ozone with Saturated Polymers and Model Compounds. Thesis Dissertation, Institute of Chemical Physics, Moscow, 1973 [in Russian],... 

Physical fractionation, of oils, 10 813-814 Physical materials standards, 15 742 Physical metallurgy, 16 127 Physical models, for process control, 20 687 Physical netpoints, in shape-memory polymers, 22 356, 358... 

Physical models of fuel cell operation contribute to the development of diagnoshc methods, the rational design of advanced materials, and the systematic ophmization of performance. The grand challenge is to understand relations of primary chemical structure of materials, composition of heterogeneous media, effective material properties, and performance. For polymer electrolyte membranes, the primary chemical structure refers to ionomer molecules, and the composition-dependent phenomena are mainly determined by the uptake and distribuhon of water. 

AS the solvent in a polymer solution becomes poorer, e.g., through a temperature change, a phase transition will eventually take place. There have been a number of reports on the phase transition polymers in response to various external stimuli such as pH [1-5], temperature [6-10], light [11-14], and chemical substances [15-20], These polymer systems have been model systems for understanding the fundamental and classic problems in polymer physics. 

During the operation of a polymer-electrolyte fuel cell, many interrelated and complex phenomena occur. These processes include mass and heat transfer, electrochemical reactions, and ionic and electronic transport. Only through fimdamental modeling, based on physical models developed from experimental observations, can the processes and operation of a fuel cell be truly understood. This review examines and discusses the various regions in a fuel cell and how they have been modeled. 

Fan, C.F. and Hsu, S.L. (1992). A study of stress distribution in model composite by finite-element analysis. II fiber/matrix interfacial effects.. /. Polym. Sci. Part B Polym. Physics 30, 619-635. 

A better knowledge of force constants, the use of more detailed physical models, and the availability of large computers and of new methods of calculation has permitted the prediction, within close approximation, of the frequencies and, to a lesser degree, the intensities of absorptions of stereoregular polymers in ordered conformations (helix, zigzag, etc.). In this way data on molec-... 

Many dispersions are stabilised by polymers. The underlying interaction is often called the steric force. For the understanding of steric interactions it is necessary to know some fundamentals of polymer physics (a good introduction is the book of Strobel [190]). Here we are mainly concerned about linear polymers because these are commonly used for steric stabilization. Fortunately, in many applications we do not need to consider the detailed molecular chemical nature of the polymer such as effects of bond lengths, bond angles, rotation energy, etc. In many discussions we can use simpler models to describe the polymer. 

The gas-polymer-matrix model for sorption and transport of gases in polymers is consistent with the physical evidence that 1) there is only one population of sorbed gas molecules in polymers at any pressure, 2) the physical properties of polymers are perturbed by the presence of sorbed gas, and 3) the perturbation of the polymer matrix arises from gas-polymer interactions. Rather than treating the gas and polymer separately, as in previous theories, the present model treats sorption and transport as occurring through a gas-polymer matrix whose properties change with composition. Simple expressions for sorption, diffusion, permeation and time lag are developed and used to analyze carbon dioxide sorption and transport in polycarbonate. 

In Section I we introduce the gas-polymer-matrix model for gas sorption and transport in polymers (10, LI), which is based on the experimental evidence that even permanent gases interact with the polymeric chains, resulting in changes in the solubility and diffusion coefficients. Just as the dynamic properties of the matrix depend on gas-polymer-matrix composition, the matrix model predicts that the solubility and diffusion coefficients depend on gas concentration in the polymer. We present a mathematical description of the sorption and transport of gases in polymers (10, 11) that is based on the thermodynamic analysis of solubility (12), on the statistical mechanical model of diffusion (13), and on the theory of corresponding states (14). In Section II we use the matrix model to analyze the sorption, permeability and time-lag data for carbon dioxide in polycarbonate, and compare this analysis with the dual-mode model analysis (15). In Section III we comment on the physical implication of the gas-polymer-matrix model. 

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