Non-solvents

Cement, Portland 65-85 A27Y Polyvinyl chloride resin, solvent, non-solvent. ... 

Chlorinated rubber is usually prepared by bubbling chlorine into a solution of masticated rubber in a chlorinated hydrocarbon solvent such as carbon tetrachloride. Hydrochloric acid is removed during the reaction. The solvent may be removed by vacuum or steam distillation or by precipitation of the derivative by a non-solvent such as petroleum. 

Nienow and Conti (1978) developed a model of partiele abrasion at high solids eoneentration based on Rittinger s law of eomminution. When tested experimentally using eopper sulphate and niekel ammonium sulphate erystals in two non-solvent liquids, measured abrasion rates were eonsistent with a seeond-order dependenee of eoneentration as predieted (Figure 5.12). 

The term solvent is loosely applied to the volatile component of a paint, though this component may in fact consist of a true solvent for the medium plus a non-solvent or diluent. When such a mixture is used, usually with the aim of reducing cost or obtaining a higher solids content at a given viscosity, care must be taken to ensure that the diluent is more volatile than the true solvent in order that the medium shall remain in solution during the drying process. 

Determination of the nature of the sulfate content was attempted by following the conch of this impurity in two ways (1) during the course of laboratory simulated industrial stabilization procedures, and (2) from successive dissolutions of unstabilized NC samples in various solvents and subsequent repptn from non-solvents. This approach was based on the premise that free occluded sulfuric acid would be released from the fibers by the soln-pptn treatment, whereas chemically combined sulfate would remain unaffected. The fuli details of the various expts can be found in Ref 5 some typical results are shown in Table 3 for four samples of NC of different nitrogen content... 

In good solvents, a polymer becomes well solvated by solvent molecules and the conformation of its molecules expands. By contrast, in poor solvents a polymer is not well solvated, and hence adopts a relatively contracted conformation. Eventually of course, if the polymer is sufficiently poor the conformation becomes completely contracted, there are no polymer-solvent interactions, and the polymer precipitates out of solution. In other words, the ultimate poor solvent is a non-solvent. 

Xylan-based micro- and nanoparticles have been produced by simple coacervation (Garcia et al., 2001). In the study, sodium hydroxide and chloride acid or acetic acid were used as solvent and non-solvent, respectively. Also, xylan and surfactant concentrations and the molar ratio between sodium hydroxide and chloride acid were observed as parameters for the formation of micro- and nanoparticles by the simple coacervation technique (Garcia et al., 2001). Different xylan concentrations allowed the formation of micro- and nanoparticles. More precisely, microparticles were found for higher concentrations of xylan while nanopartides were produced for lower concentrations of the polymer solution. When the molar ratio between sodium hydroxide and chloride acid was greater than 1 1, the partides settled more rapidly at pH=7.0. Regarding the surfactant variations, an optimal concentration was found however, at higher ones a supernatant layer was observed after 30 days (Garda et al., 2001). 

Dissolution/reprecipitation processes were evaluated for the recycling of poly-epsilon-caprolactam (PA6) and polyhexamethyleneadipamide (PA66). The process involved solution of the polyamide in an appropriate solvent, precipitation by the addition of a non-solvent, and recovery of the polymer by washing and drying. Dimethylsulphoxide was used as the solvent for PA6, and formic acid for PA66, and methylethylketone was used as the non-solvent for both polymers. The recycled polymers were evaluated by determination of molecular weight, crystallinity and grain size. Excellent recoveries were achieved, with no deterioration in the polymer properties. 33 refs. 

The Vinyloop process is based on the selective dissolution of PVC used in composites applications like cable insulation, flooring, tarpaulins, blisters, etc. After removal of insoluble parts like metals, rubber or other polymers, the PVC is reprecipitated with all additives by introduction of a non-solvent component whieh will form with the seleetive solvent an azeotropie mixture. By using typical conditions, the process is able to reeover a pure PVC eompound powder ready for use without any additional treatment like melt filtration or a new pelletisation (speeific characteristics of the powder are average diameter of 400 microns and bulk density above 600 kg/ eub.m). All the solvents used are eompletely reeyeled and reused. PVC compounds recovered in the Vinyloop process can be reused in a closed-loop recycling scheme... 

Non-solvent refined mineral oils and contaminated used mineral oils... 

These thermolysis reactions normally produce polymeric products, free of the cyclic analogs, in essentially quantitative yield and in sufficient purity to give satisfactory elemental analysis upon removal of the sHyl ether byproduct under vacuum. Final purification is generally achieved by precipitation of the polymer into a non-solvent such as hexane. With the exception of poly(diethylphosphazene) (2), which is insoluble in all common solvents (see below), the new polymers are readily soluble in CH CU and CHCU. In addition, the phenyl substituted compounds (3-6) are soluble in THF andvanous aromatic solvents. None of the polymers are water-soluble however, Me2PN]n (1) is soluble in a 50 50 water/THF mixture. 

Chen, H Wu, J.-C. and Chen, H.-Y. (1995) Preparation of ethylcellulose microcapsules containing theophylline by using emulsion non-solvent addition method. Journal of Microencapsulation, 12, 137-147. 

A portion of the white film from each package was heated in TCB containing 0.1% w/v of N-phenyl-2-naphthylamine as an antioxidant. The portion of the white film not covered by the label was sampled for the "bad" package sample. The "good" packages had no label. The nominal polymer concentration in solution was 2 mg/mL. The samples were filtered hot through 0.5-pm pore size glass fiber filters. TCB is a non-solvent for PET. Therefore, only the PE and EVA layers were dissolved. The middle PE layer accounted for about 80% of the film thickness. PET and EVA were minor components of the film. 

Fig. 1. General overview of a PHA production process. All PHA production processes consist of a fermentation and a recovery step, followed by polymer processing for specific applications. In many cases the fermentation is divided into two stages, a biomass production and a PHA accumulation stage (for further detail see text). Several methods for recovery of the material have been described, of which solvent-based and non-solvent-based recovery protocols are illustrated...

ZENECA has developed a non-solvent based recovery process as an alternative to solvent extraction for the commercial production of poly(3HB) and poly(3HB-co-3V) by A. eutrophus [94,95], In this process the cells were first exposed to a temperature of 80 °C and subsequently treated with a cocktail of various hydrolytic enzymes consisting of lysozyme, phospholipase, lecithinase, the proteinase alcalase, and others. Most of the cellular components were hy-... 

Following solubilization of the PHA from the defatted plant material, recovery of PHA from the solvent can be accomplished in various ways (Fig. 5) [74-78]. Addition of a PHA non-solvent to the solution would lead to PHA precipitation. If a solvent was used which dissolves PHA only under high temperature and pressure, cooling the solvent may be used to recover the polymer. Alternatively, evaporation of the solvent could also lead to polymer precipitation. Each of these methods have their disadvantages. Precipitation of PHA... 

Fig. 6. Flow diagram of the extraction of PHA from oilseeds using a combination of PHA solvent and a marginal non-solvent (oil) for PHA...

The stability of these dispersions has been investigated. A strong dependence of critical flocculation conditions (temperature or volume fraction of added non-solvent) on particle concentration was found. Moreover, there seems to be little or no correlation between the critical flocculation conditions and the corresponding theta-conditions for the stabilising polymer chains, as proposed by Napper. Although a detailed explanation is difficult to give a tentative explanation for this unexpected behaviour is suggested in terms of the weak flocculation theory of Vincent et al. 

The stability of the various dispersions was assessed and compared by determining the critical flocculation conditions (temperature or volume fraction of added non-solvent for the grafted polymer), as a function of particle concentration. 

For both kinds of polymer-grafted particles, flocculation was induced either by changing the temperature or by adding a nonsolvent for the stabilising polymer. In this way critical flocculation temperature (c.f.T) and critical flocculation vol. fractions of non-solvent (c.f.v.) values were obtained, in general as a function of . 

The adsorption of block and random copolymers of styrene and methyl methacrylate on to silica from their solutions in carbon tetrachloride/n-heptane, and the resulting dispersion stability, has been investigated. Theta-conditions for the homopolymers and analogous critical non-solvent volume fractions for random copolymers were determined by cloud-point titration. The adsorption of block copolymers varied steadily with the non-solvent content, whilst that of the random copolymers became progressively more dependent on solvent quality only as theta-conditions and phase separation were approached. 

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