It can also be produced by various catalytic processes such as Ziegler — Natta catalysis or Cr — silica catalysis. What are the Properties of High - Density Polyethylene? HDPE has numerous applications due to its unique properties.
To understand its various uses in the industry, you need to know its properties first. Therefore, various pro perties of HDPE are listed below —. It can be molded again and again. Thus, it is a thermoplastic polymer. It is well known for its high, strength to density ratio. It has little branching in its structure. It has stronger intermolecular forces and tensile strength than low density polyethylene. Its melting point is Its temperature of crystallization is It is harder and more opaque than low density polyethylene.
It is resistant to many different solvents. Its latent heat of fusion is It shows chemical and electrical resistance. It is able to resist lower temperatures than LDPE. It is a strong and lightweight plastic polymer. What are the Uses of High - Density Polyethylene? All of the above stated desirable properties of high — density polyethylene make it suitable for numerous applications.
Few applications of HDPE are listed below —. It is used to make disposable suits for various purposes. It is applicable to make pipes which can be used for potable water and sewage water as well. Its fibers can be spun into a rope. It is used as house wrap to protect buildings.
Plastic envelopes which are generally used in mailing are made up of HDPE. It is used in making chairs, stools, ice cube trays, bottles etc. But the reactions were explosive and safety concerns prompted the now defunct ICI, which merged into Dutch-based Akzo Nobel , to halt the research. Fawcett had been disappointed that the research was not allowed to continue, and his attempts to make the scientific community recognize his and Gibson's achievements led in September to what became known as the "Fawcett disclosure," records Carol Kennedy in her book ICI: The Company that Changed Our Lives.
At a major conference, attended by some of the world's most eminent scientists, Fawcett told delegates that he had made a solid polymer of ethylene, with a molecular weight of about But the consensus at the time was that ethylene could not polymerize because the double bond could only be activated at very high temperatures, explains Valentina Brunella, a polymer chemistry scientist at Italy's University of Turin.
In December that year, Williams and colleagues Michael Perrin and John Paton reinvestigated the experiments of Gibson and Fawcett using ethylene alone.
Under similar experimental conditions - but with better equipment - they observed a pressure drop, and when the reaction finished there were 8.
Williams, Perrin and Paton had been lucky. The vessel had leaked and, it was later confirmed, a trace of oxygen was present in the fresh ethylene that had been added to the reaction vessel to replace the leaked gas. The fresh ethylene contained, by chance, the right amount of oxygen to act as an initiator. He was speaking at a Royal Society of Chemistry meeting in to commemorate the discovery of PE, also known as polythene.
For once it didn't explode - usually it did - and we thought something must be wrong. So we left it to cool overnight. And when I looked inside the metal container the next day, I found what looked like a lump of sugar. In fact, that 'sugar' was polythene. A member of ICI's dyestuffs division, Bernard Habgood, recognized that PE could supersede gutta-percha, a natural material, for insulation of submarine cables.
This provided the impetus to proceed to commercial scale production. Posted by Nana Hinsley on Fri, Feb 13, On March 27, , two organic chemists working for the Imperial Chemical Industries Research Laboratory were testing various chemicals. O Gibson and E. Fawcett's surprise the white, waxy substance they were testing would become a revolutionary substance that would change the world.
Polyethylene was born! The researchers set off a reaction between ethylene and benzaldehyde, in an autoclave. It seems their testing container sprang a leak and all of the pressure escaped. There was the white, waxy substance that greatly resembled plastic. Upon carefully repeating and analyzing the experiment, the scientists discovered that the loss of pressure was only partly due to a leak; the major reason was the polymerization process that had occurred leaving behind polyethylene.
The first patents for polythene were registered in by Imperial Chemical Industries. A year later the first practical use for the material, as a film, was discovered.
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