Mixed phases, charge transfer systems

There was no significant damage to equipment in the fire tests, and it was demonstrated that a Jet Airmix mixer may safely handle the mixing of RP formulations on a routine basis. Since a high risk of fire is always associated with any method of transfer of RP, a pneumatic conveying system [dynamic air, two phase positive pressure transfer system was evaluated to load RP into the Jet Airmix mixer. Electrostatic charge measurements were minimal and indicated the system was satisfactory to load the blender. 

When two polymeric systems are mixed together in a solvent and are spin-coated onto a substrate, phase separation sometimes occurs, as described for the application of poly (2-methyl-1-pentene sulfone) as a dissolution inhibitor for a Novolak resin (4). There are two ways to improve the compatibility of polymer mixtures in addition to using a proper solvent modification of one or both components. The miscibility of poly(olefin sulfones) with Novolak resins is reported to be marginal. To improve miscibility, Fahrenholtz and Kwei prepared several alkyl-substituted phenol-formaldehyde Novolak resins (including 2-n-propylphenol, 2-r-butylphenol, 2-sec-butylphenol, and 2-phenylphenol). They discussed the compatibility in terms of increased specific interactions such as formation of hydrogen bonds between unlike polymers and decreased specific interactions by a bulky substituent, and also in terms of "polarity matches" (18). In these studies, 2-ethoxyethyl acetate was used as a solvent (4,18). Formation of charge transfer complexes between the Novolak resins and the poly (olefin sulfones) is also reported (6). 

CaFa-PhMe system obeys Raoult s law despite the significant heat of mixing. Solid-liquid phase equilibrium diagrams have been determined for the CaFa-cyclohexa-1,3-diene (exploratory measurements only) and CeFa-cyclo-octa-l,5-diene systems, both of which form addition compounds, and for CaFa-cyclohexane (no compound formation) in this case the tesults are discussed in terms of charge-transfer complexes. ... 

Electrode reactions involve charge transfer as a fundamental step, wherein a neutral species is converted into an ion, or an ion is converted into a neutral species. Both reactions thus involve electron transfer. At the cathode, the charge transfer reaction involves the conversion of an oxygen molecule into oxide ions. The electrodes in solid state electrochemical devices may either be purely electronic conductors, or may exhibit both ionic and electronic conductivity (the so-called mixed ionic electronic conduction, MIEC). In addition, the electrodes may be either single phase or composite, two-phase. For the purposes of illustration, in what follows we will examine the overall cathode reaction in a system with a single phase, purely electronically conducting electrode. 

The methods used for introducing feed streams into continuous reactors can be quite important. All ingredients are charged and mixed before the latex is formed in most batch reactor processes. The major purposes of mixing after the reaction begins are to facilitate heat removal through the cooling surface and to maintain mass transfer from the monomer phase to the polymer particles. With a CSTR reaction system, however, the feed streams are added to partially converted latexes, and other factors need to be considered. 

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