Solvents polymer solubility

Liquid solvent/polymer Solubility parameter, <5, (J/cm ) / Molar volume, V (cm /mol)... 

Solvent/polymer solubility is the dominating factor for the formation process of particle nuclei from solution. Here we show real examples and then discuss the overall control of size distribution. 

For high molecular-weight polymer-solvent systems, the polymer critical concentration is close to zero and the interaction parameter has a value close to 0.5. Thus, a good solvent (polymer soluble in the solvent at all proportions) is obtained if < 0.5, whereas values greater than 0.5 indicate poor solvency. Since we mentioned that the model is only an approximate representation of the physical picture and that the FH parameter is often not a constant at all, this empirical rule is certainly subject to some uncertainty. Nevertheless, it has found widespread use and its conclusions are often in good agreement with experiment. 

Dispersing the layered silicate in a solution of the polymer in an organic solvent, followed by either solvent evaporation or polymer precipitation. The limitations of this method are shown by the large amounts of organic solvents, polymer solubility and poor filler dispersion. ... 

In production, anhydrous formaldehyde is continuously fed to a reactor containing well-agitated inert solvent, especially a hydrocarbon, in which monomer is sparingly soluble. Initiator, especially amine, and chain-transfer agent are also fed to the reactor (5,16,17). The reaction is quite exothermic and polymerisation temperature is maintained below 75°C (typically near 40°C) by evaporation of the solvent. Polymer is not soluble in the solvent and precipitates early in the reaction. 

Reaction and Heat-Transfer Solvents. Many industrial production processes use solvents as reaction media. Ethylene and propylene are polymerized in hydrocarbon solvents, which dissolves the gaseous reactant and also removes the heat of reaction. Because the polymer is not soluble in the hydrocarbon solvent, polymer recovery is a simple physical operation. Ethylene oxide production is exothermic and the catalyst-filled reaction tubes are surrounded by hydrocarbon heat-transfer duid. 

The polymer has a low cohesive energy density (the solubility parameter 5 is about 16.1 MPa ) and would be expected to be resistant to solvents of solubility parameter greater than 18.5 MPa. Because it is a crystalline material and does... 

The process of post-chlorinating PVC was carried out during World War II in order to obtain polymers soluble in low-cost solvents and which could therefore be used for fibres and lacquers. The derivate was generally prepared by passing chlorine through a solution of PVC in tetrachloroethane at between 50°C and 100°C. Solvents for the product included methylene dichloride, butyl acetate and acetone. These materials were of limited value because of their poor colour, poor light stability, shock brittleness and comparatively low softening point. 

The polymer, being amorphous, is soluble in solvents of similar solubility parameter, grades with low residual acetate being dissolved in solvents of solubility parameter between 19.8 and 22 MPa. ... 

The advantage of the activated displacement polymerization is the facile incorporation of different and unconventional structural units in the polymer backbone. Most of the heteroarylene activated polyethers prepared by this route are soluble in many organic solvents. The solubility behavior of new polyethers is shown in Table 8. In contrast to many polyphenylenequi-noxalines, poly(aryl ether phenylquinoxalines) prepared by the quionoxaline activated displacement reaction are soluble in NMP. Solubility in NMP is important since it is frequently used for polymer processing in the microelectronics industry [27]. 

When using this approach to polymer solubility, we need to remember that the basis is thermodynamics. In other words, this approach gives information about the energetics of solubility, but does not give any insight in the kinetics of the process. In order to promote rapid dissolution, it may be more helpful to employ a solvent that is less good thermodynamically, but that consists of small, compact molecules that readily diffuse into the polymer and hence dissolve the polymer more quickly. 

Microspheres and microcapsules of lactide/glycolide polymers have received the most attention in recent years. Generally, three microencapsulation methods have been employed to afford controlled release formulations suitable for parenteral injection (1) solvent evaporation, (2) phase separation, and (3) fluidized bed coating. Each of these processes requires lactide/glycolide polymer soluble in an organic solvent. 

To remove water, the benzene was azeotroped and distilled over CaH2. The n-pentane was stored over LiAlH and distilled over CaH2. Toluene was distilled over CaH2. Toluene from Burdick Jackson, Muskegon, MI could also be used for dilute solution characterization without any adverse effects on polymer solubility. Tetrahydrofuran (THF) was dried over molecular sieves and doubly distilled over CaH2. The solvents were blanketed with nitrogen to maintain dryness. 

Chemicals of various types are used in every stage of drilling, completing, and producing oil and gas wells. This review describes these chemicals, why they are used, and recent developments. These chemicals include common inorganic salts, transition metal compounds, common organic chemicals and solvents, water-soluble and oil-soluble polymers, and surfactants. As existing fields become depleted, use of chemistry to maintain production via well stimulation, more efficient secondary recovery operations, and enhanced oil recovery become ever more important. 

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