Despite not even being theorised a century ago, today, polyolefin shrink wrap is in huge demand. There has been a century of rapid innovation that has led to us being able to use the stuff today. In this article, we explore the unlikely history of polyethylene.
When Was Polyethylene First Created?
The concept of high molar mass macromolecules – an academic way to describe polymers – was first theorised in the 1920s by future Nobel Prize winner Hermann Staudinger. However, the first confirmed traces of polyolefin were created in 1933. In the small village of Winnington, two scientists – Fawcett and Gibson – left two chemicals (ethylene and benzaldehyde) overnight by accident in their laboratory, and discovered an unexpected white powder weighing about a gram left behind. When they tried to repeat the experience, without benzaldehyde – they did not realise they left any behind – the reactor exploded. It took two more years before they managed to repeat the production of the white powder – and yet again, it was entirely due to luck, when a leak allowed traces of oxygen to contaminate the ethylene which, at high temperatures, created polyethylene. They quickly began mass production and testing of the new substance.
In 1937, the process was patented by Imperial Chemical Industries where the two scientists worked, and by 1939 a hundred tons a year were produced in the first factory to make LDPE, or low-density polytheylene. The LDPE was largely used in the food industry thanks to its food-friendly advantages to substitute metals, and is still used to this end today.
When Mass Production of Polyethylene Began
One important use of the polymer was as insulation for another recent invention, radar. The Battle of Britain was won in part because of radar insulators, made from LDPE. However, during the Second World War and directly afterwards, research slowed. Most companies thought they could use polyethylene for fuel for the army, which ended up being fruitless.
It took until the 1950s before two major breakthroughs took place. Firstly, two men at Phillips Petroleum Company were doing research on a mixture of nickel oxide and chromium oxide compounds. However, unexpectedly (if not accidentally), they plugged their reactor with solid HDPE instead. After fiddling for a little while with the reactor, they found they could polymerise ethylene with their catalyst, and later on, polymerise propylene as well. They immediately filed for patents and licensing the process using their catalysts and became immensely rich as a result – nowadays, Philips catalysts represent 40-50% of the global production of HDPE, and their specific method is still popular around the world.
The second innovation took place under Ziegler in the Max Planck Institute in Germany, another future Nobel Prize winner for his work in polymers. In 1953, Ziegler found a way of producing mass polyethylene using titanium tetrachloride. Because of the way the two reacted together, polymerisation led to three times as much of polyethylene as before, creating an extremely efficient way to produce the plastic. By 1957, the first plant was set up to produce the new plastic through the German’s technique. Ziegler’s work was especially valuable because he rigorously theorised exactly how to make polyethylene, which ultimately was why he was later on awarded the Nobel Prize for his work with synthetic polymers.
Discovery of new catalysts
By the 1970s, another ‘incident’ led to the discovery of a new catalyst for polymerisation. The University of Hamburg were investigating the side reactions that occurred during Ziegler’s experiments. During their experiment, however, polyethylene unexpectedly formed ethylene outside of the experiment, tramsmitted by moisture inside the machinery. It turned out that water was reacting with one of their materials – trimethylaluminium – to form a new polyolefin which was even more catalytic than before, dubbed MAO, a cluster of methyl, aluminium, and oxygen.
This discovery led to a flurry of more catalytic substances that led to better olefin polymerisation, and so better polyolefin production. For decades after the fact, and still now, scientists are looking into how polyolefins can be created more and more effectively with new base chemicals.
From polyethylene to polyolefin shrink wrap
Shrink wrap, as we have covered before in our history of food packaging, began impacting the food industry almost immediately. By the 1950s, shrink wrapping became immediately successful and shrink wrap machinery was sold across the world to package fresh vegetables. However, its popularity soon spread to other industries as well. By 1983, for example, the first shrink wrap machine was installed in a commercial laundry in the United States.
Today, the shrink wrap industry is huge and spread across a variety of different industries from marine shrink wrapping boats and and wrapping pallets for freight transportation to disaster relief like shrinkwrapping roofs and food to extend shelf life. The size of the shrink film industry has extended over the years and is still continuing to grow at a rapid rate.
The story of polyolefin is one of how an accidentally-made substance of barely a gram has became the centre of an industry producing over 700,000 tons of material a year. If you think your business might benefit from polyolefin shrink wrap, please get in touch and we will be more than happy to provide help you with anything you need.