Polyethylene origin

Table 6 shows the sales estimates for principal film and sheet products for the year 1990 (14). Low density polyethylene films dominate the market in volume, followed by polystyrene and the vinyls. High density polyethylene, poly(ethylene terephthalate), and polypropylene are close in market share and complete the primary products. A number of specialty resins are used to produce 25,000—100,000 t of film or sheet, and then there are a large number of high priced, high performance materials that serve niche markets. The original clear film product, ceUophane, has faUen to about 25,000 t in the United States, with only one domestic producer. Table 7 Hsts some of the principal film and sheet material manufacturers in the United States.

The solvent is 28 CC-olefins recycled from the fractionation section. Effluent from the reactors includes product a-olefins, unreacted ethylene, aluminum alkyls of the same carbon number distribution as the product olefins, and polymer. The effluent is flashed to remove ethylene, filtered to remove polyethylene, and treated to reduce the aluminum alkyls in the stream. In the original plant operation, these aluminum alkyls were not removed, resulting in the formation of paraffins (- 1.4%) when the reactor effluent was treated with caustic to kill the catalyst. In the new plant, however, it is likely that these aluminum alkyls are transalkylated with ethylene by adding a catalyst such as 60 ppm of a nickel compound, eg, nickel octanoate (6). The new plant contains a caustic wash section and the product olefins still contain some paraffins ( 0.5%). After treatment with caustic, cmde olefins are sent to a water wash to remove sodium and aluminum salts. 

Another subclass of substituted amides that is of great commercial value is the ethoxylated amides. They can be synthesized from alkanolamides by chain extending with ethylene or propylene oxide or by ethoxylation directly from the primary amide (46—48). It was originally beheved that the stepwise addition of ethylene oxide (EO) would produce the monoethano1 amide and then the diethanolamide when sufficient ethylene oxide was added (49), but it has been discovered that only one hydrogen of the amide is substituted with ethylene oxide (50—53). As is typical of most ethylene oxide adducts, a wide distribution of polyethylene oxide chain length is seen as more EO is added. A catalyst is necessary to add ethylene oxide or propylene oxide to a primary or an ethoxylated amide or to ethoxylate a diethoxy alkanolamide synthesized from diethanolamine (54). 

To complete the assembly of a cell, the interleaved electrode groups are bolted to a cov er and the cover is sealed to a container. Originally, nickel-plated steel was the predominant material for cell containers but, more recently plastic containers have been used for a considerable proportion of pocket nickel-cadmium cells. Polyethylene, high impact polystyrene, and a copolymer of propylene and ethylene have been the most widely used plastics. 

The process was originally developed in the 1940s for use with vinyl plas-tisols in liquid form. It was not until the 1950s that polyethylene powders were successfully moulded in this way. Nowadays a range of materials such as nylon, polycarbonate, ABS, high impact polystyrene and polypropylene can be moulded but by far the most common material is polyethylene. 

PET, see Polyethylene terephthalate Petit, Rowland, 524 Petroleum, catalytic cracking of, 100 composition of, 99-100 gasoline from. 99-100 history of, 99 refining of, 99-100 Pharmaceuticals, approval procedure for, 165 origin of, 164 Phenol(s), 599... 

An example of the way in which process competition works in the manufacture of plastics is the story of acrylonitrile. The first process for the production of this plastic was based upon the reaction between hydrogen cyanide and acetylene, both hard to handle, poisonous, and explosive chemicals. The raw material costs were relatively low as compared to materials for other monomers, but the plant investment and manufacturing costs were too high. As a result, originally acrylonitrile monomer (1950s) sold for about 30 cents per pound and the future of the material looked dim as other plastics such as polyethylene became available at much lower prices due to their lower production costs. 

When polyethylene was first produced in the early 1940s, physicists in England, USA, and Germany predicted a tremendous potential for it. At that time the properties of PEs were much lower than those presently available. Out of that original general-purpose PE, have been developed specific PEs in this polyolefin family of plastics such as LDPE, HDPE, UHMWPE, and so on. In turn their different properties, as well as other plastics, continually increase and their variables continue to be reduced and/or easier to process to tighter tolerances. 

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