Polyvinyl chloride , precipitation

A development of interest to the chemical industiy is the tubular precipitator of reinforced-plastic construction (Wanner, Gas Cleaning Plant after T1O2 Rotary Kilns, technical bulletin, Lurgi Corp., Frankfurt, Germany, 1971). Tubes made of polyvinyl chloride plastic are reinforced on the outside with polyester-fiber glass. The use of modern economical materials of construction to replace high-maintenance materials such as lead has been long awaited for corrosive applications. 

Carboxylic acids often have been identified by means of paper chromatography Clarke and Bazill (10) have extracted plasticizers from polyvinyl chloride first with ether and then with methanol. Subsequently the extracts were saponified with alcoholic potassium hydroxide, and the precipitated potassium salts were isolated and converted into free acids. These, in alcoholic solution, were then applied to paper and chromatographed ascendingly with a mixture of butanol, pyridine, water, and ammonia the migration period was about six hours. A number of additional color tests facilitated identification of unknown acids. 

Physical effects caused by polyethylene glycol bases include softening and liquefaction in mixtures with phenol, tannic acid, and salicylic acid. Discoloration of sulfonamides and dithranol can also occur and sorbitol may be precipitated from mixtures. Plastics, such as polyethylene, phenolformaldehyde, polyvinyl chloride, and cellulose-ester membranes (in filters) may be softened or dissolved by polyethylene glycols. Migration of polyethylene glycol can occur from tablet film coatings, leading to interaction with core components. 

Polyvinyl chloride [9002-81-2]. Precipitate it from cyclohexanone by addition of MeOH. 

Polyvinyl chloride Red-brown Blood red, brown-red Blood red, brown-red Red-brown, black precipitate Red-brown Black-brown... 

When solid polymer precipitates fiom bulk, solution, suspension, or emulsion polymerizations by a chain mechanism, the kinetics of the reaction and properties of the product may change sharply. If the solid phase is not swollen by the reaction mixture, the active site of the polymerization is isolated from possible termination reactions and may produce pronounced auto acceleration and increases in molecular weight of polymer formed. This behavior was quantified for one chain reaction polymer, polyvinyl chloride, covered in this book. Micldey (9) showed that polyvinyl chloride synthesis in bulk followed a two term kinetics equation with the second term representing incremental increases in polymerization rate due to accelerated polymerization in precipitated particles of polymer. 

Polyvinyl chloride Stirring of a concentrated solution of tetrahydrofuran into methanol Plasticisers, emulsifiers remain in solution, PVC and its polymers are precipitated... 

A modification of bulk polymerization that is a heterogeneous system is one in which the polymer product precipitates. Typical polymers that can be produced by this technique are polyacrylonitrile and polyvinyl chloride. The polymerization rate for polyvinyl chloride is given by... 

The term "suspension polymerization" is used traditionally for polymerization in a dispersed monomer phase. Occasionally the term is also u for the type of process described in the preceeding section, but for that the term "precipitation polymerization" is more appropiate. The polymerization in a dispersed monomer phase might also be called "dispersion polymerization", but this term is used for polymerizations where the monomer is originally dissolved, and the polymer is separated as a second liquid phase, usually absorbing some monomer. Suspension polymerization is used on a large scale for the manufacture of polyvinyl chloride (PVC), and for specific grades of polystyrene. 

Another close analogy is the precipitation mass polymerization system for polyvinyl chloride (PVC). In that case, the polymer does precipitate from the monomer, but it does not go through a self-adhering sticky stage. This allows... 

Most bulk polymerizations are homogeneous. However, if the polymer is insoluble in its monomer and precipitates as the reaction proceeds, the process is sometimes known as heterogeneous bulk or precipitation polymerization. Two examples of such polymers are polyacrylonitrile and polyvinyl chloride (PVC). The latter is produced commerdaJly by a heterogeneous bulk process, which allows control of particle size and porosity for optimum plasticizer absorption. Such heterogeneous polymerizations do not follow the kinetic scheme developed in Chapter X for homogeneous reactions. 

SOX Denhardt s solution 1% (w/v) Ficoll, 1% (w/v) polyvinyl pyrrolidone, 1% (w/v) BSA. Filter-sterilize. Store aliquots at-20°C. Eto not flame the pipets used to transfer this solution. Denaturation and precipitation of the protein result from the use of hot pipets at this stage. Template DNAfor the production of hybridization probes must be pure. Standard methods, such as dye-buoyant density ultracentrifugation, generate acceptable products. Ethidium bromide and cesium chloride are removed prior to use of the DNA (4). 

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