Polyvinyl chloride processing/applications

EVA copolymers have low crystallinity because the acetate branches interfere with crystallization. These resins are characterized by increased flexibility and resilience over a wide temperature range and by improved clarity. EVA copolymers are widely used as a nonplasticizer alternative for polyvinyl chloride (PVC) applications. These copolymers also have higher moduli than standard elastomers and are preferable in that they are more easily processed without the need to vulcanize. 

The development of electrical power made possible the electrochemical industry. Electrolysis of sodium chloride produces chlorine and either sodium hydroxide (from NaCl in solution) or metallic sodium (from NaCl fused). Sodium hydroxide has applications similar to sodium carbonate. The ad vantage of the electrolytic process is the production of chlorine which has many uses such as production of polyvinyl chloride. PVC, for plumbing, is produced in the largest quantity of any plastic. 

The properties of a polymer depend not only on its gross chemical composition but also on its molecular weight distribution, copolymer composition distribution, branch length distribution, and so on. The same monomer(s) can be converted to widely differing polymers depending on the polymerization mechanism and reactor type. This is an example of product by process, and no single product is best for all applications. Thus, there are several commercial varieties each of polyethylene, polystyrene, and polyvinyl chloride that are made by distinctly different processes. 

Polyvinyl chloride resin, because of its inherent thermal instability and wide range of applications, requires us to develop additive recipes based on specific application and processing requirements. Typical additive packages include stabilizers, plasticizers, waxes, processing aids, pigments, and mineral additives. 

Chlorine (from the Greek chloros for yellow-green ) is the most abundant halogen (0.19 w% of the earth s crust) and plays a key role in chemical processes. The chlor-alkali industry has been in operation since the 1890s and improvements in the technology are still important and noticeable, for example, the transition from the mercury-based technology to membrane cells [60]. Most chlorine produced today is used for the manufacture of polyvinyl chloride, chloroprene, chlorinated hydrocarbons, propylene oxide, in the pulp and paper industry, in water treatment, and in disinfection processes [61]. A summary of typical redox states of chlorine, standard potentials for acidic aqueous media, and applications is given in Scheme 2. 

There is every indication that the next several years will witness a continued rapid increase in the use of petroleum raw materials in the production of elastomers and plastics, and that the petroleum companies will become increasingly active, not only in providing the starting materials, but also in operating the chemical processes of converting them to the required monomers and polymers. The current increase in production of thermoplastic resins such as polystyrene, polyvinyl chloride, polyethylene, and acrylonitrile polymers is based on the development of widespread new applications at the consumer level, and the outlet for plastic materials in many of these uses is presently limited by the capacity to produce and process the resins rather than by consumer demand. 

This technique has also been employed for the preparation of a catalytic imprinted membrane by coating a cellulose membrane with a polymer incorporating particles imprinted with the transition-state analogue of a dehydrofluorination reaction [264]. The application of such an MIP composite membrane as the recognition element in an optical sensor has been reported for digitoxin analysis in serum samples by embedding digitoxin-MIP particles in polyvinyl chloride film in presence of plasticizer by the dry inversion process [265],... 

At times, low- or high-intensity blending alone can produce a suitable product for use by the fabricator. An example of this would be a polyvinyl chloride (PVC) blend used for several large-volume extrusion applications. More frequently, however, a compounding process is required to obtain the desired physical property. The five primary compounding processes used in the industry for controlling the above parameters are single-screw extrusion (SSE), twin-screw extrusion (TSE), continuous mixers, batch mixers, and kneaders. Table 18.1 summarizes key aspects of each process. 

Application A process to produce polyvinyl chloride (PVC) from vinyl chloride monomer (VCM) using suspension polymerization. Many types of PVC grades are produced including commodity, high K-value, low K-value, matted type and co-polymer PVC. The PVC possesses excellent product qualities such as easy processability and good heat stability. 

Application Production of suspension polyvinyl chloride (PVC) resins from vinyl chloride monomer (VCM) using the Vinnolit process. 

Application Adding a stripping column to existing polyvinyl chloride (PVC) plants to remove vinyl chloride monomer (VCM) from PVC slurry. The recovered VCM can be reused in the PVC process, without any deterioration of PVC polymer quality. 

Post-chlorinated polyvinyl chloride (cPVC) is a material which offers a combination of mechanical strength, temperature and corrosion resistance and low installation costs, that meets a variety of process uses. This comprehensive article describes cPVC s key properties in detail and highlights the various industries and applications for the polymer, particularly pipes and fittings. 

Another application in macromolecular chemistry is radiation-induced graft polymerization, by which favourable properties of two polymers can be combined. In this process, copolymers of A and B are produced by irradiation of the polymer A in the presence of the monomer B. Examples are graft polymers of polyethylene and acrylic acid or of polyvinyl chloride and styrene. The properties of textiles (cellulose, wool, natural silk, polyamides, polyesters) can also be modified by graft polymerization, for example for the production of weatherproof products. 

Most common metal oxide and metal chalcogenide semiconductors have valence-band edges that lie positive of the oxidation potentials of most organic functional groups, and thermodynamics will thus favor photocatalytic oxidation. For efficient processes to take place, an easily oxidizable donor is required, but a whole range of substrates have been shown to be useful for this application. For example, a Japanese group has shown that this purpose is served not only by pure compounds, but even by wastes such as polyvinyl chloride, algae, protein, dead insects, and animal excrement, which function as electron sources [104]. Thus, synthetic utility is attained only if this wide reactivity is controlled. In practice, selectivity is best controlled by the adsorption and oxidation potential effects [105],... 

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