Development of Polyethylene

The first to record the preparation of polyethylene was von Pechmann in 1898 [1], followed shortly thereafter by Bamberger and Tschimer [2]. In both cases polyethylene was prodnced by the decomposition of diazomethane, but the commercial significance of the discovery went unappreciated. Strictly speaking, the decomposition of diazomethane yields polymethylene, the only difference between this and linear polyethylene being that polymethylene molecules can have any number of carbon atoms, whereas polyethylene must have an even number. Friedrich and Marvel, in a 1930 paper [3], reported the unexpected polymerization of ethylene to a non-gaseous product. They did not appreciate the signifi- 

This reaction was not reproducible attempts to repeat it sometimes led to uncontrollable exothermic reactions with accompanying excessive pressure that damaged equipment. It was not untill December 1935 that Michael Perrin established a set of conditions that could be used to polymerize ethylene consistently. His first successful experiment yielded approximately 8g of polyethylene. The key to reproducibility lay in the contamination of the ethylene by trace levels of oxygen. Oxygen reaeted with ethylene to yield peroxides that subsequently decomposed to yield Iree radicals that initiated the polymerization process. 

The polyethylene made by Perrin was a ductile material with a melting temperature of about 115°C. This material was what we know today as low density polyethylene. In 1936 ICI took out the first patent on the manufacture of polyethylene [6]. 

The properties of the new material produced in Perrin s experiment were investigated, and its potential as an electrical insulator was soon recognized, along with its chemieal inertness and inherent flexibility. Work continued on the project, with the aim of developing the apparatus necessary for commercial production. 

The successful development of the required plant was no small achievement, involving the design of a reaction vessel capable of withstanding a pressure of 22,500 psi. A pilot plant was established in 1937, and by the ontbreak of World War II, ICI was producing polyethylene commercially. Even before the first commercial unit came on-stream, it was recognized that it wonld not meet the expected demand. A newer and bigger line was commissioned, which went into production in 1942. 

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When the development of polyethylene tereph-thalate (PET) occurred, ethylene glycol already was being produced in large amounts from ethylene, a by-product of petroleum cracking, by the oxidation of ethylene to ethylene oxide and subsequent hydration to ethylene glycol, which, in a noncatalytic process, uses high pressure and temperature in the presence of excess water. 

Joe Schwarcz tells it like it is. Whether he s plumbing the mysteries of chicken soup or tracing the development of polyethylene, Schwarcz takes a little history, adds a dash of chemistry, and produces a gem of an essay every time. I wish he d been my chemistry professor when I was in school. ... 

Plastics have achieved a dominant position in agriculture and horticulture over the past twenty years, which has merited the new description plasticulture. This is in part due to the replacement of glass in greenhouses and tunnels by polyethylene, but more particularly in the development of polyethylene mulcK. Polyethylene for greenhouse films... 

We have seen the development of polyethylene, from low molecular weight polymers first mentioned by name in the literature in 1869, to the first reported solid polymers of linear polyethylene by Prof. Marvel in 1930 then the unintentional synthesis and chance observation of 0.4 g of solid polyethylene in March 1933 by ICI (prepared under high pressure, later described as LDPE) the onset of catalyst technology in the industry, from the simultaneous discoveries of transition metal catalysts a few decades later, that created the HOPE industry the development of LLDPE copolymers and the discovery in 1979 of metallocene catalysts for polyolefin polymerization - all of which are now part of the mainstream polyethylene industry. Post-metaUocene catalysts offer the promise of branching without high pressure or comonomers the potential to incorporate polar groups without high pressure, and to control this copolymer microstructure. 

In the 1950s, two chromium-based eatalysts, Ziegler-Natta and Phillips, were introdueed for use in polymerisation reaetions. The Phillips eatalyst is part of the industrial development of polyethylene and is still in use today. Using these eatalysts as a template, researehers are developing chromium-based catalysts for the polymerisation of monomers other than ethene, including the formation of polycarbonates from epoxides and carbon dioxide. 

Figure 6.27 Morphology development of polyethylene/polyamide-6/SEBS-g-MA reactive blends system in an intermeshing co-rotating twin-screw extruder [74].

Imuta, J. Toda, A. Tsutsui, T. Hachimori, T. Kashiwa, N. Development of polyethylene copolymers manufacturing technologies and synthesis of new functionalized polyolefins with designed catalysts. Bull. Chem. Soc. Jpn. 2004, 77, 607-615. 

Chang H, Lee K-G, Schultz JM. Structure development of polyethylene terephthalate (PET) fibers during post-spinning annealing. J Macromol Sci Phys 1994 B33 105-127. 

The MFI test originated in the laboratories of Imperial Chemical Industries (Id), in the early stages of development of polyethylene, and was mainly used in the... 

Despite the broad field of applications (packing, household goods, industry,. ..), development of thermoplastics in new applications is limited by the finding of scientific-technological answers leading to an improvement in their properties, at the same time that the price of the reagents and the overall process are kept low. Development of polyethylene with inorganic fillers in the nanoscale is mainly addressed to improve the mechanical and barrier properties, as well as to reduce flammability. 

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