Polyvinyl chloride, mechanisms carbonization

In those days, the mechanisms of carbonization of polyvinyl chloride (PVC) were also under study in our laboratory. We found that PVC transformed to a beautiful lustrous pitch upon heating to 400°C under nitrogen. This PVC pitch could be spun quite easily, by comparison with molten lignin, and thus the pitch-based carbon fiber was first prepared in essentially the same way as the lignin-based carbon fiber. We recognize now that we were fortunate in first using PVC pitch. We later tried many other pitches as raw materials for carbon fiber, but PVC pitch was the only one that could be spun without any pretreatment. This was in 1963. We immediately applied for a patent (2 ), and the fundamentals of pitch preparation and spinning as well as the structure of the finished fibers were published in 1965 (3 ). 

Most UF membranes are made from polymeric materials, such as, polysulfone, polypropylene, nylon 6, PTFE, polyvinyl chloride, and acryhc copolymer. Inorganic materials such as ceramics, carbon-based membranes, and zirconia, have been commercialized by several vendors. The important characteristics for membrane materials are porosity, morphology, surface properties, mechanical strength, and chemical resistance. The membrane is tested with dilute solutions of well-characterized macromolecules, such as proteins, polysaccharides, and surfactants of known molecular weight and size, to determine the MWCO. 

A free-radical mechanism of the stabilizing action of diallqrlstan-nane derivatives in the process of photodecomposition of polyvinyl chloride has been proposed in an interpretation of the results obtained in an investigation of the activity of dibutyltin diacetate, labelled with carbon in the butyl group. After the irradiation, the butyl group is detected in polyvinyl chloride. Apparently the formation of cross-links and oxidation of the macromolecules during UV irradiation of the polymer is prevented when the butyl group is added to the macroradicals. The possible mechanism of the action of dibutyltin diacetate is described by the scheme [42] ... 

Recently, Goddart et al. [6] reported a polyvinyl alcohol-copper(ll) initiating system, which can produce branched polymers on surfaces. The initiating system is prepared by dissolving polyvinyl alcohol in water that already contains copper nitrate (or copper chloride). The calcium carbonate filler is dipped into the solution and dried. If this is used for polymerization of an olefin (say, styrene), it would form a polymer that adheres to the particles, ultimately encapsulating them. The mechanical properties of calcium-carbonate-fiUed polystyrene have been found to depend strongly on filler-matrix compatibihty, which is considerably improved by this encapsulation. 

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