毕业论文要附2000字的英文参考,我就是找不到这方面的英文资料,有没有朋友有的?
是关于聚氯乙烯地板革生产或销售等方面的英文.
注意,是关于这方面的英文,要2000字以上
我会加分...
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Polyvinyl Chloride Floor Cover
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Polyvinyl chloride, (IUPAC Polychloroethene) commonly abbreviated PVC, is a widely used thermoplastic polymer. In terms of revenue generated, it is one of the most valuable products of the chemical industry. Around the world, over 50% of PVC manufactured is used in construction. As a building material, PVC is cheap, durable, and easy to assemble. In recent years, PVC has been replacing traditional building materials such as wood, concrete and clay in many areas.
Polyvinyl chloride is used in a variety of applications. As a hard plastic, it is used as vinyl siding, magnetic stripe cards, window profiles, gramophone records (which is the source of the term vinyl records), pipe, plumbing and conduit fixtures. The material is often used in Plastic Pressure Pipe Systems for pipelines in the water and sewer industries because of its inexpensive nature and flexibility. PVC pipe plumbing is typically white, as opposed to ABS, which is commonly available in grey and black, as well as white.
It can be made softer and more flexible by the addition of plasticizers, the most widely-used being phthalates. In this form, it is used in clothing and upholstery, and to make flexible hoses and tubing, flooring, to roofing membranes, and electrical cable insulation. It is also commonly used in figurines.
Polyvinyl chloride is produced by polymerization of the monomer vinyl chloride, as shown. Since about 57% of its mass is chlorine, creating a given mass of PVC requires less petroleum than many other polymers.
History
Polyvinyl chloride was accidentally discovered on at least two different occasions in the 19th century, first in 1835 by Henri Victor Regnault and in 1872 by Eugen Baumann. On both occasions, the polymer appeared as a white solid inside flasks of vinyl chloride that had been left exposed to sunlight. In the early 20th century, the Russian chemist Ivan Ostromislensky and Fritz Klatte of the German chemical company Griesheim-Elektron both attempted to use PVC (polyvinyl chloride) in commercial products, but difficulties in processing the rigid, sometimes brittle polymer blocked their efforts. In 1926, Waldo Semon and the B.F. Goodrich Company developed a method to plasticize PVC by blending it with various additives. The result was a more flexible and more easily-processed material that soon achieved widespread commercial use.
Polyvinyl chloride is one of our most common synthetic materials. Commonly known as “PVC” or “vinyl,” polyvinyl chloride is a tremendously versatile resin, appearing in thousands of different formulations and configurations. In the U.S. we produced over ten billion pounds of PVC resins in 1992. Among plastics, it is second in quantity only to polyethylene. PVC is by far the most common plastic used in construction, where 6.3 billion pounds of resin were used in 1992. PVC compounds (the resin combined with various additives) turn up in applications as varied as sewer pipes, wire sheathing, flooring and weather-stripping (see table).
While some vinyl products such as siding and flooring have long had critics, recently the entire PVC industry has come under fire for environmental reasons. The loudest of these recent attacks are aimed not only at PVC but at the broader issue of chlorine use in industrial society. As reported in recent issues of EBN, Greenpeace is calling for the phase-out of all chlorine-based industries, including PVC, for a range of health and environmental reasons. Groups that are less political than Greenpeace have also spoken out against chlorine use, though not as strongly against PVC in particular. These include the International Joint Commission on the Great Lakes (IJC) and the American Public Health Association (APHA).
In the wake of all this publicity, many builders and architects are questioning the wisdom of specifying materials made from PVC and looking into alternatives. To make intelligent choices, however, especially in such a contentious debate, it’s useful to know some of the background.
How It’s Made
PVC is comprised of chlorine, carbon, and hydrogen. The chlorine most often comes from a brine solution of common rock salt (sodium chloride). The chlorine is separated by electrolysis: a strong electric current across the liquid solution attracts sodium ions to the (negatively charged) cathode, while chlorine collects at the anode.
Until recently the electrolysis required the use of liquid mercury as the cathode, and traces of toxic mercury frequently contaminated by-products and liquid effluents. Most manufacturers no longer use mercury; however, in 1992 only 14% of U.S. chlorine production used mercury.
The most common chlorine separation process today, used in 77% of U. S. production, relies on a diaphragm in the electrolysis tank. A newer, membrane-based method is being adopted at all new facilities because it is both more energy-efficient and produces higher value by-products than the other systems. This membrane technology accounts for about 7% of chlorine production.
The PVC industry is the largest single consumer of industrial chlorine worldwide, using about 30% of all chlorine produced. The remainder goes into paper production, pesticides, pharmaceuticals, and a huge range of other products and processes. Some chlorine-based refrigerants and propellants (CFCs and HCFCs) are being phased out due to concern about their damage to the ozone layer.
In addition to chlorine, the electrolysis of salt creates caustic soda (sodium hydroxide), used in making soaps, paper, and rayon, and as a neutralizer in many other industries. While initially chlorine was an unwanted by-product of caustic soda production, demand for chlorine has increased so much that caustic soda has become relatively inexpensive, leading to its use in more and more processes.
PVC resin is 57% chlorine by weight. The rest is hydrogen and carbon, which are derived from fossil fuels: primarily natural gas and petroleum. Almost all PVC today is made from ethylene, which is the petrochemical of choice for many industrial processes. In the U.S. ethylene is made by cracking ethane in a reactor at about 800°C. (Ethane is a lightweight hydrocarbon that is extracted during the refining of natural gas.) Many of the by-products of ethylene manufacture (olefins, diolefins, and methane) are used in other industries. An older process of producing vinyl chloride by combining chlorine with acetylene, while no longer competitive with the ethylene-based process, is still used at one or two existing plants where the large infrastructure investment has locked the manufacturer into that process.
Ethylene and chlorine are combined to make 1,2-dichloroethane (EDC), which is then converted to vinyl chloride. Vinyl chloride, commonly referred to in the industry as VCM (for “vinyl chloride monomer”), is a gas at normal temperature and pressure. The by-product of converting EDC to vinyl chloride is hydrochloric acid.
EDC is made from ethylene and chlorine by two processes: direct chlorination, which uses pure chlorine; and oxychlorination, in which ethylene is combined with hydrochloric acid (see formulas). The oxychlorination process takes place at higher temperatures and produces many more toxic by-products than direct chlorination; it is done primarily to utilize the hydrochloric acid by-product from the conversion of EDC to vinyl chloride.
PVC is produced by combining vinyl chloride into chains or polymers. Several different processes are used for polymerization, each of which gives the polymer different properties. By far the most common is the suspension process. Vinyl chloride is stirred into water, together with small amounts of methyl cellulose and organic peroxides, agents that initiate polymerization and keep the polymerized particles from conglomerating. The contents of the polymerization chamber have to be stirred vigorously throughout the six- to eight-hour process. In addition, the process must be cooled constantly, since it generates heat on the order of 660 Btus/lb of PVC. Cooling is accomplished by running water through the sides of the polymerization tanks, using about 30 gallons of water per pound of PVC produced.
The process is terminated when about 90% of the vinyl chloride has polymerized. Leftover vinyl chloride monomer is drawn off using a vacuum and largely recovered. Until recently, traces of vinyl chloride remained in the PVC material. The realization that vinyl chloride tended to leach into food or water from PVC containers, combined with the discovery that it is carcinogenic, have led to strict controls on the amount of residual vinyl chloride in PVC, especially containers for food and water.
To meet these requirements, PVC manufacturers have added a separate steam-stripping process to remove almost all residual monomer from the PVC. After the stripping, the PVC is in the form of small particles suspended in water. These are spun dry in a centrifuge and then air-dried before packaging.
Besides the suspension process, two other polymerization processes create PVC for certain applications. An emulsion process is used to produce finer particles of PVC, which are used for vinyl pastes—also called plastisols—from which some vinyl flooring is made. A mass process is simpler, though it is less flexible in terms of adding copolymers (other plastic resins mixed with the PVC to enhance certain properties). Mass polymerization accounts for about 20% of the PVC manufactured in the U.S.
History of the PVC Industry
PVC was first produced in a laboratory in 1872. It began to be produced commercially in the 1930s, when techniques for mixing it with plasticizers became known and PVC emerged as a substitute for rubber. During World War II, German scientists developed PVC pipe for water supply systems when material shortages limited conventional pipe supplies.
In the 1950s and 1960s many U.S. companies established facilities for polymerizing vinyl chloride into PVC. At that time the polymerization was done in open vats, requiring relatively little capitalization. High levels of worker exposure to vinyl chloride in the process were not considered hazardous, though they typically produced a narcotic effect. “We used to joke about getting a cheap high from it,” says Professor Rudolph Deanin of the University of Massachusetts at Lowell, who worked in PVC production during that period.
In 1971 a rare cancer of the liver, angiosarcoma, was traced to vinyl chloride exposure among PVC workers, and strict workplace exposure limits were established by the Occupational Safety and Health Administration (OSHA). These restrictions necessitated radical changes in the manufacturing environment— all polymerization vats had to be sealed and controlled. The cost of these changes and the increasing economies of scale enjoyed at larger plants eventually eliminated smaller producers, who either shut down their PVC production facilities or were bought out by the larger producers.
Today the North American PVC market is dominated by about a dozen large manufacturers. A few of these, such as Occidental Petroleum, Inc., operate facilities for all phases of the process, from chlorine and ethylene production to end products. Most, however, purchase some of the refined materials from other producers. Dow Chemical Company produces large quantities of vinyl chloride for sale to other companies but produces no PVC itself.
Additives
PVC resin alone is not all that useful. It mixes with additives relatively easily, however, lending a broad range of PVC compounds with various properties. Actual PVC resin often comprises only about 70% of PVC end-products and sometimes as little as 35% or 40%. The PVC may be mixed with other polymer resins during its production (copolymers), or any of a huge range of additives that are mixed in later. The most common additives include plasticizers, which give PVC the flexibility associated with many vinyl products, and stabilizers, which reduce its tendency to degrade under various conditions. The process of mixing these additives with the PVC is called compounding. Compounding may be done by the PVC manufacturers, by companies specializing in this process alone, or by the producers of end-products.
Plasticizers
Plasticizers comprise a huge range of chemicals, mostly derived from fossil-fuel. They are used in all PVC products that require flexibility, such as electrical cables, hoses, gaskets, and vinyl sheet flooring. Plasticizers are used with other plastic resins as well, but the PVC industry consumes the vast majority (about 80%) of all plasticizers. While PVC is inherently fire-resistant because of its high chlorine content, the addition of plasticizers reduces this resistance and makes it necessary to add fire-retardants as well.
The most common traditional plasticizer is known as DOP or DEHP (for di-2-ethylhexyl phthalate). About nine million tons of DOP are produced annually worldwide. DOP was identified as a suspected carcinogen in 1987, and its use in medical blood bags was suspended when it was found to be leaching into the stored blood. There are also concerns about DOP released into the environment. The EPA’s Toxic Release Inventory (TRI) reports that over one million pounds of DOP were released into the air in 1991.
Stabilizers
Stabilizers are added to PVC to reduce degradation, primarily from heat or ultraviolet light. The main chemical function of stabilizers is to prevent the formation of hydrochloric acid within the PVC (or absorb any that is formed), because the acid promotes degradation of the material.
Traditionally, heavy metals such as cadmium and lead were used as stabilizers. Due to concerns about the toxicity of these elements, the industry has been switching to alternatives for many applications. Nevertheless, a recent article in Plastics Engineering reports that 15% of all the cadmium in municipal solid waste incinerator ash comes from PVC products. Lead also continues to be used in large-diameter pipes and in insulation for electrical cables (see page 15). Common replacements for these metals are calcium-zinc and barium-zinc formulations. Higher costs and technical difficulties are the reasons cited for not using these alternatives in all applications.
Other additives
The list of other additive categories for PVC products is lengthy: processing aids, impact modifiers, pigments, inert fillers such as chalk, lubricants that aid in extrusion, flame retardants, smoke suppressants, biocides. These additives are generally used in much smaller quantities than the plasticizers and stabilizers, and most of them are also used in compounds based on other (non-PVC) plastic resins.
太长了，自己去抄：http://www.buildinggreen.com/auth/article.cfm?fileName=030101b.xml
另外参考：
History of PVC floor cover (PDF Magazine): http://www.solvinpvc.com/static/wma/pdf/1/1/6/2/5/Wave15_UK.pdf
PVC building products: http://www.vinylbydesign.org/site/page_two_col.asp?TRACKID=&CID=30&DID=6
Polyvinyl Chloride Floor Cover
==============================
Polyvinyl chloride, (IUPAC Polychloroethene) commonly abbreviated PVC, is a widely used thermoplastic polymer. In terms of revenue generated, it is one of the most valuable products of the chemical industry. Around the world, over 50% of PVC manufactured is used in construction. As a building material, PVC is cheap, durable, and easy to assemble. In recent years, PVC has been replacing traditional building materials such as wood, concrete and clay in many areas.
Polyvinyl chloride is used in a variety of applications. As a hard plastic, it is used as vinyl siding, magnetic stripe cards, window profiles, gramophone records (which is the source of the term vinyl records), pipe, plumbing and conduit fixtures. The material is often used in Plastic Pressure Pipe Systems for pipelines in the water and sewer industries because of its inexpensive nature and flexibility. PVC pipe plumbing is typically white, as opposed to ABS, which is commonly available in grey and black, as well as white.
It can be made softer and more flexible by the addition of plasticizers, the most widely-used being phthalates. In this form, it is used in clothing and upholstery, and to make flexible hoses and tubing, flooring, to roofing membranes, and electrical cable insulation. It is also commonly used in figurines.
Polyvinyl chloride is produced by polymerization of the monomer vinyl chloride, as shown. Since about 57% of its mass is chlorine, creating a given mass of PVC requires less petroleum than many other polymers.
History
Polyvinyl chloride was accidentally discovered on at least two different occasions in the 19th century, first in 1835 by Henri Victor Regnault and in 1872 by Eugen Baumann. On both occasions, the polymer appeared as a white solid inside flasks of vinyl chloride that had been left exposed to sunlight. In the early 20th century, the Russian chemist Ivan Ostromislensky and Fritz Klatte of the German chemical company Griesheim-Elektron both attempted to use PVC (polyvinyl chloride) in commercial products, but difficulties in processing the rigid, sometimes brittle polymer blocked their efforts. In 1926, Waldo Semon and the B.F. Goodrich Company developed a method to plasticize PVC by blending it with various additives. The result was a more flexible and more easily-processed material that soon achieved widespread commercial use.
Polyvinyl chloride is one of our most common synthetic materials. Commonly known as “PVC” or “vinyl,” polyvinyl chloride is a tremendously versatile resin, appearing in thousands of different formulations and configurations. In the U.S. we produced over ten billion pounds of PVC resins in 1992. Among plastics, it is second in quantity only to polyethylene. PVC is by far the most common plastic used in construction, where 6.3 billion pounds of resin were used in 1992. PVC compounds (the resin combined with various additives) turn up in applications as varied as sewer pipes, wire sheathing, flooring and weather-stripping (see table).
While some vinyl products such as siding and flooring have long had critics, recently the entire PVC industry has come under fire for environmental reasons. The loudest of these recent attacks are aimed not only at PVC but at the broader issue of chlorine use in industrial society. As reported in recent issues of EBN, Greenpeace is calling for the phase-out of all chlorine-based industries, including PVC, for a range of health and environmental reasons. Groups that are less political than Greenpeace have also spoken out against chlorine use, though not as strongly against PVC in particular. These include the International Joint Commission on the Great Lakes (IJC) and the American Public Health Association (APHA).
In the wake of all this publicity, many builders and architects are questioning the wisdom of specifying materials made from PVC and looking into alternatives. To make intelligent choices, however, especially in such a contentious debate, it’s useful to know some of the background.
How It’s Made
PVC is comprised of chlorine, carbon, and hydrogen. The chlorine most often comes from a brine solution of common rock salt (sodium chloride). The chlorine is separated by electrolysis: a strong electric current across the liquid solution attracts sodium ions to the (negatively charged) cathode, while chlorine collects at the anode.
Until recently the electrolysis required the use of liquid mercury as the cathode, and traces of toxic mercury frequently contaminated by-products and liquid effluents. Most manufacturers no longer use mercury; however, in 1992 only 14% of U.S. chlorine production used mercury.
The most common chlorine separation process today, used in 77% of U. S. production, relies on a diaphragm in the electrolysis tank. A newer, membrane-based method is being adopted at all new facilities because it is both more energy-efficient and produces higher value by-products than the other systems. This membrane technology accounts for about 7% of chlorine production.
The PVC industry is the largest single consumer of industrial chlorine worldwide, using about 30% of all chlorine produced. The remainder goes into paper production, pesticides, pharmaceuticals, and a huge range of other products and processes. Some chlorine-based refrigerants and propellants (CFCs and HCFCs) are being phased out due to concern about their damage to the ozone layer.
In addition to chlorine, the electrolysis of salt creates caustic soda (sodium hydroxide), used in making soaps, paper, and rayon, and as a neutralizer in many other industries. While initially chlorine was an unwanted by-product of caustic soda production, demand for chlorine has increased so much that caustic soda has become relatively inexpensive, leading to its use in more and more processes.
PVC resin is 57% chlorine by weight. The rest is hydrogen and carbon, which are derived from fossil fuels: primarily natural gas and petroleum. Almost all PVC today is made from ethylene, which is the petrochemical of choice for many industrial processes. In the U.S. ethylene is made by cracking ethane in a reactor at about 800°C. (Ethane is a lightweight hydrocarbon that is extracted during the refining of natural gas.) Many of the by-products of ethylene manufacture (olefins, diolefins, and methane) are used in other industries. An older process of producing vinyl chloride by combining chlorine with acetylene, while no longer competitive with the ethylene-based process, is still used at one or two existing plants where the large infrastructure investment has locked the manufacturer into that process.
Ethylene and chlorine are combined to make 1,2-dichloroethane (EDC), which is then converted to vinyl chloride. Vinyl chloride, commonly referred to in the industry as VCM (for “vinyl chloride monomer”), is a gas at normal temperature and pressure. The by-product of converting EDC to vinyl chloride is hydrochloric acid.
EDC is made from ethylene and chlorine by two processes: direct chlorination, which uses pure chlorine; and oxychlorination, in which ethylene is combined with hydrochloric acid (see formulas). The oxychlorination process takes place at higher temperatures and produces many more toxic by-products than direct chlorination; it is done primarily to utilize the hydrochloric acid by-product from the conversion of EDC to vinyl chloride.
PVC is produced by combining vinyl chloride into chains or polymers. Several different processes are used for polymerization, each of which gives the polymer different properties. By far the most common is the suspension process. Vinyl chloride is stirred into water, together with small amounts of methyl cellulose and organic peroxides, agents that initiate polymerization and keep the polymerized particles from conglomerating. The contents of the polymerization chamber have to be stirred vigorously throughout the six- to eight-hour process. In addition, the process must be cooled constantly, since it generates heat on the order of 660 Btus/lb of PVC. Cooling is accomplished by running water through the sides of the polymerization tanks, using about 30 gallons of water per pound of PVC produced.
The process is terminated when about 90% of the vinyl chloride has polymerized. Leftover vinyl chloride monomer is drawn off using a vacuum and largely recovered. Until recently, traces of vinyl chloride remained in the PVC material. The realization that vinyl chloride tended to leach into food or water from PVC containers, combined with the discovery that it is carcinogenic, have led to strict controls on the amount of residual vinyl chloride in PVC, especially containers for food and water.
To meet these requirements, PVC manufacturers have added a separate steam-stripping process to remove almost all residual monomer from the PVC. After the stripping, the PVC is in the form of small particles suspended in water. These are spun dry in a centrifuge and then air-dried before packaging.
Besides the suspension process, two other polymerization processes create PVC for certain applications. An emulsion process is used to produce finer particles of PVC, which are used for vinyl pastes—also called plastisols—from which some vinyl flooring is made. A mass process is simpler, though it is less flexible in terms of adding copolymers (other plastic resins mixed with the PVC to enhance certain properties). Mass polymerization accounts for about 20% of the PVC manufactured in the U.S.
History of the PVC Industry
PVC was first produced in a laboratory in 1872. It began to be produced commercially in the 1930s, when techniques for mixing it with plasticizers became known and PVC emerged as a substitute for rubber. During World War II, German scientists developed PVC pipe for water supply systems when material shortages limited conventional pipe supplies.
In the 1950s and 1960s many U.S. companies established facilities for polymerizing vinyl chloride into PVC. At that time the polymerization was done in open vats, requiring relatively little capitalization. High levels of worker exposure to vinyl chloride in the process were not considered hazardous, though they typically produced a narcotic effect. “We used to joke about getting a cheap high from it,” says Professor Rudolph Deanin of the University of Massachusetts at Lowell, who worked in PVC production during that period.
In 1971 a rare cancer of the liver, angiosarcoma, was traced to vinyl chloride exposure among PVC workers, and strict workplace exposure limits were established by the Occupational Safety and Health Administration (OSHA). These restrictions necessitated radical changes in the manufacturing environment— all polymerization vats had to be sealed and controlled. The cost of these changes and the increasing economies of scale enjoyed at larger plants eventually eliminated smaller producers, who either shut down their PVC production facilities or were bought out by the larger producers.
Today the North American PVC market is dominated by about a dozen large manufacturers. A few of these, such as Occidental Petroleum, Inc., operate facilities for all phases of the process, from chlorine and ethylene production to end products. Most, however, purchase some of the refined materials from other producers. Dow Chemical Company produces large quantities of vinyl chloride for sale to other companies but produces no PVC itself.
Additives
PVC resin alone is not all that useful. It mixes with additives relatively easily, however, lending a broad range of PVC compounds with various properties. Actual PVC resin often comprises only about 70% of PVC end-products and sometimes as little as 35% or 40%. The PVC may be mixed with other polymer resins during its production (copolymers), or any of a huge range of additives that are mixed in later. The most common additives include plasticizers, which give PVC the flexibility associated with many vinyl products, and stabilizers, which reduce its tendency to degrade under various conditions. The process of mixing these additives with the PVC is called compounding. Compounding may be done by the PVC manufacturers, by companies specializing in this process alone, or by the producers of end-products.
Plasticizers
Plasticizers comprise a huge range of chemicals, mostly derived from fossil-fuel. They are used in all PVC products that require flexibility, such as electrical cables, hoses, gaskets, and vinyl sheet flooring. Plasticizers are used with other plastic resins as well, but the PVC industry consumes the vast majority (about 80%) of all plasticizers. While PVC is inherently fire-resistant because of its high chlorine content, the addition of plasticizers reduces this resistance and makes it necessary to add fire-retardants as well.
The most common traditional plasticizer is known as DOP or DEHP (for di-2-ethylhexyl phthalate). About nine million tons of DOP are produced annually worldwide. DOP was identified as a suspected carcinogen in 1987, and its use in medical blood bags was suspended when it was found to be leaching into the stored blood. There are also concerns about DOP released into the environment. The EPA’s Toxic Release Inventory (TRI) reports that over one million pounds of DOP were released into the air in 1991.
Stabilizers
Stabilizers are added to PVC to reduce degradation, primarily from heat or ultraviolet light. The main chemical function of stabilizers is to prevent the formation of hydrochloric acid within the PVC (or absorb any that is formed), because the acid promotes degradation of the material.
Traditionally, heavy metals such as cadmium and lead were used as stabilizers. Due to concerns about the toxicity of these elements, the industry has been switching to alternatives for many applications. Nevertheless, a recent article in Plastics Engineering reports that 15% of all the cadmium in municipal solid waste incinerator ash comes from PVC products. Lead also continues to be used in large-diameter pipes and in insulation for electrical cables (see page 15). Common replacements for these metals are calcium-zinc and barium-zinc formulations. Higher costs and technical difficulties are the reasons cited for not using these alternatives in all applications.
Other additives
The list of other additive categories for PVC products is lengthy: processing aids, impact modifiers, pigments, inert fillers such as chalk, lubricants that aid in extrusion, flame retardants, smoke suppressants, biocides. These additives are generally used in much smaller quantities than the plasticizers and stabilizers, and most of them are also used in compounds based on other (non-PVC) plastic resins.
太长了，自己去抄：http://www.buildinggreen.com/auth/article.cfm?fileName=030101b.xml
另外参考：
History of PVC floor cover (PDF Magazine): http://www.solvinpvc.com/static/wma/pdf/1/1/6/2/5/Wave15_UK.pdf
PVC building products: http://www.vinylbydesign.org/site/page_two_col.asp?TRACKID=&CID=30&DID=6
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第1个回答 2008-06-15
这个丰富~~
