Roll Film Holder
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 Graflex 23 Roll Film Holder for 4x5 Near Mint w Instructions $50.00 (1 Bid) Time Remaining: 3d 15h 4m |
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Short Introduction To Polyethylene: One Story, A Thousand Uses
As many brilliant inventions, polyethylene was born by chance, thanks to a lab accident in 1898 caused by Han von Pechmann, a German chemist who was heating diazomethane in a holder. In 1933, another accident occurred, this time in an English factory, the ICI Chemicals, when Eric Fawcett and Reginald Gibson applied a pressure of hundreds of atmospheres to a holder containing ethylene and benzaldehyde. In both cases, the scientists were impressed by the waxy material appeared in the holders. However, while in the first case they named it as polymethylene without investigating further, in the second they spent years trying to recreate it again, without any success.
The turning point occurred in 1935, when not an accident, but the will of another chemist, Michael Perrin, finally obtained polyethylene. Its electrical insulation property was soon recognized and, in 1939, began the industrial production of plastic films: since then, polyethylene rolls became an essential supply for any production department, requested by a wide range of companies, from food packaging to electrical wires production.
Furthermore, polyethylene is a thermoplastic material. This means that if its temperature is increased, it changes state and becomes viscous and malleable: heat-shrinking film was the next step. During the production stage it is possible to shape it as desired; the user must then heat it with hot air, a flame or an oven to shrink it up to the 50% of its volume and make it adhere perfectly to the object needing a wrap. Polyethylene is commonly used not only to cover electrical wires, but also wooden panels, as a good alternative to the paint (think of airplane models). Therefore, the objects wrapped in heat-shrinking film hold together well protected, granting a resistant and slim packaging, required in the production industry as well as in the food one. Speaking of types of polyethylene, its ultimate evolution on the market is the stretch film. As the name states, it has elastic qualities, and it is especially suitable for the protection of goods stacked on pallets or sensitive to the hot, which would be damaged by the thermo retraction.
As a consequence, the main employment of polyethylene is in the film packaging domain: the protection wrapping goods is, once again, polyethylene, like the plastic used to pack suitcases. The multiple qualities of this material, insulating, waterproof, heat-shrinking and resistant, in spite of its thickness, more and more thinner (think of the plastic wrap for food, which thickness is measured in microns), let us imagine a thousand different uses.
Lastly, polyethylene has a further quality: it is a recyclable material. Both production wastes, such as trimmering of the rolls, and used polyethylene sheets can be recovered to produce a low price packaging with an high environmental value. An opportunity today even more important, as we know that, at the base of polyethylene, there is the shortage and the inconstant price of oil.
About the Author
By Lia Contesso with support from hand stretch films.
For information visit shrink film packaging or polyolefin shrink film.
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