Polymer medium

Polymer hydroperoxy radical, formation of oxidized groups, 197 Polymer media, preparation of elaborate metal species, 238... 

Frechet, J.M.J., Svec, F. (1994). Column with Macroporous Polymer Media. United States Patent 5,344,310. 1994 August 2. 

The kinetic study of POOH decay in an inert atmosphere in the presence of another initiator (I). The initiator increases the concentration of macroradicals in the polymer media. If free radicals react with hydroperoxyl groups, one observes the acceleration of POOH decay. The rate of POOH decay in the case of induced decomposition obeys the equation... 

Besides diffusion, there is another underlying reason for leveling of reactivity of reactants in polymer media. The phenomena of leveling of reactivity of slowly reacting reactants was observed in the study of the reactions of peroxyl radicals with phenols and amines in the solid PS [23]. Later, this peculiarity was detected for different free radical reactions in the polymer matrix. All these reactions occur with rate constants much lower than kV) in polymer and cannot be limited by translational diffusion (see Table 19.6). 

All reactions collected in Table 19.6 are slow. They occur with rate constants that are sufficiently lower than the rate constants of diffusion in polymer, as well as the frequency of reactant orientation in the cage (vor =vrx P). Hence, physical processes are not limited by the rates of these reactions. However, polymer media influences the kinetics of these reactions. 

Limits of Reactivity (kmax/kmin) for Different Reactions in Liquid Phase and Polymer Media... 

The phenomena of relatively high activity of alkyl radical acceptors as antioxidants in solid polymer media seems to be the result of a line peculiarities of free radical reactions in the polymer matrix. Let us compare the features of these reactions in solution and polymer media. 

Polymer media influences the activation energy of the bimolecular reaction and causes the effect of reactivity leveling (see earlier)... 

Polymer Media Alginate (Sodium) Cellulose Sulfate Carboxy- methyl Cellulose Xanthan Carrageenan (A) Gellan Gum Poly Glutamic Acid... 

Polymer Media Polymaleic Anhydride Poly Acrylic Acid Polyvinyl Phosphonic Acid Polyvinyl Sulfonic Acid Polystyrene Sulfonate Tripoly Phosphate... 

A. I. Leonov, Nonequilibrium Thermodynamics and rheology of viscoelastic polymer media, Rheol. Acta, 15, 85-98 (1976). 

Pyshnograi GV (1996) An initial approximation in the theory of viscoelasticity of linear polymers and non-linear effects. J Appl Mech Techn Phys 37(1) 123—128 Pyshnograi GV (1997) The structure approach in the theory of flow of solutions and melts of linear polymers. J Appl Mech Techn Phys 38(3) 122—130 Pyshnograi GV, Pokrovskii VN (1988) Stress dependence of stationary shear viscosity of linear polymers in the molecular field theory. Polym Sci USSR 30 2624—2629 Pyshnograi GV, Pokrovskii VN, Yanovsky YuG, Karnet YuN, Obraztsov IF (1994) Constitutive equation on non-linear viscoelastic (polymer) media in zeroth approximation by parameter of molecular theory and conclusions for shear and extension. Phys — Doklady 39(12) 889-892... 

The reactions analyzed here (and used to generate the initial radical pairs in the polymer media) can be separated into two distinct categories those that involve lysis of one molecule into two radicals (such as the Norrish Type 1, photo-Fries, and photo-Claisen reactions) and those that require bimolecular processes in which a part of one molecule is abstracted by another (e.g., H-atom abstractions from a phenol or an amine by the lowest energy triplet state of benzophenone). Each reaction produces either singlet or triplet radical pairs and, thus, allows the influence of spin multiplicity on radical pair reaction rates to be separated somewhat from other influences, such as the natures of the polymer matrices and the radical structures. Different methods for extracting rates of processes for the radicals from both static and dynamic data will be discussed. ... 

On the basis of published information, a set of design criteria for dye and polymer materials can be defined for optical recording. The primary function of the dye molecule is to absorb the incident laser energy. Several groups have shown that the sensitivity of dye-polymer media is largely determined by the optical eflSciency of the thin film. Optical efficiency is a measure of the optical energy coupled into the film and is a function of the dye concentration, the dye absorption coefficient, and the layer thickness. 

The photochemical as well as thermal behavior of organic photochromic molecules is influenced in various ways by the characteristics of the polymer media in which they are incorporated. More importantly, the interaction between the photochromic and polymeric entities can lead to novel photoinduced properties beyond the obvious color changes. Because of this, photochromic polymers have been of extensive interest in interdisciplinary research. 

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