Rubber, PVC and bubblegum
Waldo Semon
Like so many innovations, the success of PVC – the world’s second most-used plastic, after polyethylene – is down to an accidental discovery. Waldo Semon, a young chemical engineer a few months into his first proper job with rubber producer BF Goodrich, had meant to find an adhesive that would bond rubber to metal. Semon decided to work with polyvinyl chloride, a brittle polymer universally thought to be totally useless. In an attempt to remove the chlorine, Semon solvated the PVC with a high-boiling solvent before treating it with zinc or a strong organic amine. “Imagine my surprise when I found that the solvated PVC was flexible, resilient and would bounce!,” he later said. “When I later found that the plasticised PVC would resist alkaline, strong acids and most solvents it seemed to me that it would have quite a range of commercial possibility.”
Convincing the management of this potential would prove a challenge in its own right, solved through a canny combination of PVC-coated (and therefore waterproofed) curtains, a vice president fond of camping (but tired of leaking tents) and an ad-hoc demonstration involving a bulging in-try and a decanter of water.
Today, PVC is the material of choice for two out of three water pipes and three quarters of the world’s sanitary sewers, with other applications ranging all the way from credit cards and window frames to electrical insulation tape.
Semon, meanwhile, didn’t rest on his laurels: he went on to develop a process and formula for synthetic rubber – a highly sought-after commodity during World War II, considering that the war had cut off supplies of natural rubber from Asia and Germany would not reveal the secret of producing “Buna-S”, the only other known synthetic rubber at the time. Through hard work and determination, Semon and his team developed the Ameripol rubber process, which by 1944 saw the US produce twice as much synthetic rubber as the world’s production of natural rubber had totaled before the war.
Engineering the sexual revolution
George Rosenkranz, Luis Miramontes and Carl Djerassi
Not all of chemical engineering’s contributions revolve around heavy industry, chemicals and refining. In pharmaceuticals, too, they have made their mark – and one of their contributions to the pharma industry has had social consequences that could hardly have been more profound.
If you’re a modern woman, who takes it for granted that women can expect the same sort of career path as men and who revels in the liberty of being able to choose if and when to have children, then you, too, owe a debt to George Rosenkranz, Luis Miramontes and Carl Djerassi. The three – two chemical engineers and one chemist, two Jewish refugees from Europe and one local Mexican – were responsible for synthesising the first synthetic progesterone, which would go on to be used in the contraceptive pill.
Building on a process discovered by the maverick chemist Russel Marker, who synthesised progesterone from sapogenins, natural steroids found in Mexican yams, Rosenkranz, Miramontes and Djerassi created a synthetic variant that not only was a lot more active, but would also survive absorption through the digestive tract.
Not that anyone thought of using it as a contraceptive, at least to begin with; initial target indications were menstrual disorders and, ironically, infertility. Even once its contraceptive effect became known, fear of religiously-motivated boycotts caused companies to veer away from the drug. Rosenkranz says: “I went around Europe and the world offering the contraceptive, but nobody wanted it.”
A sustained campaign by women’s rights campaigners Margaret Sanger and Katharine Dexter McCormick, backed up by deep pockets and research funding, changed all that. Today, the Pill is used by over 100m women ever day. The freedom to choose and time when to have children has allowed women to claim equality in the workplace, and the sharp drop in birth rates in countries wherever the Pill is easy to obtain is arguably chemical engineering’s greatest-ever contribution to sustainability.
From fuel hero to climate zero
Thomas Midgley
Not everyone who changed the world did so in a way we’d celebrate. And sometimes, it takes the benefit of hindsight to realise the true impact of an apparently beneficial innovation. That certainly is the case for Thomas Midgley – mechanical engineer, chemist and chemical engineer – who during his lifetime was celebrated as a prolific inventor with a can-do attitude who had solved the longstanding and damaging problem of engine knock and gifted the world affordable and safe coolants for refrigerators and air conditioning units, as well as a universal safe propellant for aerosols.
Today, he is described, in a much less reverential tones, as the man who “had more impact on the atmosphere than any other single organism in Earth’s history.” Midgley’s innovations? Tetraethyl lead and chlorofluorocarbons (CFCs).
Midgley had, by all accounts, a brilliantly inventive mind, untroubled by received wisdom and undaunted by even the most complex tasks. When his scientific reasoning sent him in the wrong direction, strokes of sheer luck would deliver the unexpected breakthrough, such as in the discovery of TEL. Though his hands-on pragmatic attitude makes for chilling reading for today’s engineers, especially when it comes to the conditions found in the early TEL production plants and Midgley’s cheerful dismissal of the warnings he received about TEL’s poisonous side-effects.
While there were some early indications of the dangers of TEL (even if they were downplayed and dismissed at the time), it would take much longer for the side effects of Midley’s second innovation to become known. For thirty years, CFCs – particularly Midgley’s innovation, Freon – were the workhorse of the refrigeration industry and the propellant of choice in just about any hairspray, deodorant or insecticide spray. Unlike the available alternatives, Freon was neither toxic, flammable nor explosive.
At the time of Midgley’s untimely death at the age of 55, he was highly celebrated and decorated, holder of numerous awards and prestigious offices. His legacy stayed with us for many years more, though perhaps not in the way he and his contemporaries might have anticipated.
Cool inventions
Carl von Linde and William Hampson
The liquefaction and separation of air is one of those processes that many engineers worked on over the years, but only one – or rather two – would succeed at. Two very similar processes for the liquefaction of air were independently developed in Germany and the UK and patented within weeks of each other; the first by the mechanical engineer Carl von Linde, the second by a hitherto unknown, classics graduate and barrister William Hampson.
Both used air itself as a refrigerant, exploiting the Joule Thompson effect, which describes how gas gets colder as it expands. The effect is even more pronounced if the gas was previously compressed and chilled. Harnessing the effect in a virtuous cycle, by allowing compressed cooled air to expand in a counter-current heat exchanger so it cools the incoming compressed air to ever-lower temperatures, both inventors eventually cooled the air to -190ºC: the point at which it turns liquid.
It might have taken von Linde three days of running increasingly cold air through an incredibly long steel tube which he’d packed in wool for insulation, but on 29 May 1895, he eventually got there: “With clouds rising all around it, the pretty bluish liquid was poured into a large metal bucket,” he writes in his autobiography. “The hourly yield was about three litres. For the first time on such a scale air had been liquefied, and using tools of amazing simplicity compared to what had been used before.”
Where von Linde was an engineer, industrialist and already an expert in refrigeration before he started, Hampson was a complete unknown, with no relevant training and no record of what might have perked his interest in sciences and engineering. Nevertheless, his process was both simpler and more efficient than von Linde’s, liquefying air in a mere 20 minutes compared with the three days of von Linde’s early attempts.
The Hampson-Linde cycle gave rise to the modern industrial gases industry, provided pure gases for countless industrial processes and paved the way for the discovery of several rare gases.
Degrees of separation
Csaba Horváth
There are those who have hailed chromatography as one of the most significant developments of the 20th century, and yet few people outside a chemistry lab would have any understanding of what chromatography is, or what it is used for. A classic ‘behind the scenes’ technology, chromatography is the workhorse of analytical chemistry, and finds extensive use in healthcare, quality control, and drug discovery to name but a few fields.
Pharmaceutical companies use it to isolate active ingredients and ensure accurate dosing, hospitals use it to identify poisons or drugs in patients’ blood; environmental laboratories rely on it to check for contaminants; forensic scientists apply it to analyse samples from a crime scene; industrial chemists rely on it to determine the composition of petroleum oil, check the level of additives in foods, monitor pesticide contamination, and so on.
Key to making the process widely applicable was the adaptation of gas chromatography to liquids. This opened up its use for the separation of organic and biological molecules, many of which are involatile and too fragile for vaporization.
That achievement goes to the Hungarian born chemical engineer, Csaba Horváth, the father of modern high performance liquid chromatography. Horwath took an early interest in separation sciences and – unusually for a chemical engineer during the 1960s – in biochemical engineering. Adapting recent advances in gas chromatography to the nascent science of liquid chromatography, Horváth dramatically speeded up throughput and ramped up sensitivity while reducing the size of the equipment.
Today, HPLC is so sensitive that the characteristic patterns of peaks not only identify different molecules in a sample, but – thanks to very subtle differences in production processes and batch chemistry that give chemicals a very unique “fingerprint” also the production plant they came from.
Csaba Horváth may not be a household name, but without him, the world would be a much scarier place.
Man of steel
Henry Bessemer
If the industrial revolution was built on steel, then the father of the industrial revolution was Henry Bessemer. It was the Bessemer process that made steel available in industrial quantities at an affordable price.
Patented in 1855, the Bessemer process reduced the cost of steel from £50–60/t to £6–7/t and was accompanied by vast increases in scale and speed of steel production. Steel girders for bridges, buildings, railroads, skyscrapers – all were unimaginable before Bessemer. The same goes for modern steel ships, steel wire, high-pressure boilers (and with them, the steam engine), not to mention turbines for power generation.
Bessemer was a prolific inventor. Despite no university education, he patented innovations in fields as diverse as pigment production and ship building.
During his experiments with steelmaking, he discovered that contact with hot air would turn pig iron into steel, prompting Bessemer to take the – at the time highly counter-intuitive – step of forcing air directly through the molten iron. He was lucky that the resulting reaction, which was extremely violent, did not permanently damage to his workshop. But at least after just 20 minutes of mild explosions, violent eruptions and showes of red-hot slag, Bessemer was left with a converter full of steel.
Once he had convinced himself that there was no way of toning down the violence of the reaction, Bessemer channelled his efforts into developing a reactor vessel designed to contain the violent inferno with some degree of reliability and safety. The result: the Bessemer Converter.
This in turn prompted the rise of steel as a ubiquitous construction material, driving the second industrial revolution, and made Henry Bessemer a very, very wealthy man indeed.
Power Stores
Yoshio Nishi
Handheld electronics and gadgets – from mobile phones to laptops – have transformed the way we live over the past decade or so. But the revolution led by Steve Jobs and his slightly less famous compatriot, Adam Osborne (the inventor of the laptop), would not have been possible without high-power rechargeable batteries, and they were brought to market thanks to a chemical engineer. Like many engineers, Yoshio Nishi is not a household name but frankly he should be, for he led the team that turned the lithium ion battery from a research concept into practical, commercially viable reality.
Nishi, who studied solid physical chemistry at the engineering department of Keio University in Tokyo, spent a lifetime working for Sony. In the mid-1980s he was appointed general manager of the lithium ion battery development team.
Lithium ion batteries promised to overcome the environmental problems associated with nickel-cadmium batteries, and also had a much greater energy density. Even so in the early stages of development many thought that lithium was too dangerous, the technology too risky and the whole concept premature.
One of the biggest challenges was making the battery safe even when subjected to serious abuse.
The team devised vents to prevent overpressure, introduced a porous membrane separating anode and cathode that would become impermeable in the event of a temperature spike, added elements with a positive temperature coefficient to prevent thermal runaway, and designed a mechanical link that would disconnect the cathode lead if pressure built up inside the battery.
Even so, lithium ion batteries have caused many phones and laptops to spontaneously combust over the years, triggering huge product recalls. Nishi blames price competition putting pressure on engineers to use cheaper materials and other shortcuts, and device designers ignoring the battery’s usage specifications.
His advice: Engineers have a duty to ensure management understands the safety implications of cost cuts, and not to compromise easily on what they believe is important.
Driving units and progress
Arthur D Little
If chemical engineering is the application of science to industry, then one of its most influential pioneers was Arthur D Little. Founder of the international consultancy that bears his name, Little’s achievements stretch much further: he developed the concept of unit operations – still a cornerstone of the profession – and used it to define the role of chemical engineering in industrial chemistry. He was also one of six founding members of the American Institute of Chemical Engineers and the driving force behind the creation of the chemical engineering practice school at the Massachusetts Institute of Technology in 1920.
Little was far ahead of his time in recognising the importance of long-term industrial research. The turn of the century saw rapid industrial development and process design, but corporate R&D remained an intermittent and hap-hazard affair, stopping and starting on a project-by-project basis. Little was an early and vociferous proponent of organised, longterm R&D, both within companies and at universities, which he lambasted for failing to provide adequate equipment for industrial research.
The consultancy he set up was one way of filling this gap. Little and the people he hired applied themselves tirelessly to improving processes and perfecting products. Their tenacity paid off: within five years of its foundation in 1905, the Arthur D Little consultancy had made a name for itself and ran specialised departments covering fuel engineering, forest products, textiles and more.
To the profession, his most lasting legacy is the concept of unit operations. He explained: “Any chemical process, on whatever scale conducted, may be resolved into a coordinate series of what may be termed ‘unit operations’, as pulverising, dyeing, roasting, crystallising, filtering, evaporation, electrolysing and so on.” He added that the number of different unit operations is quite finite – the great complexity of chemical engineering is the result of the variety of conditions under which these unit operations are carried out.
Almost 100 years later, his analysis remains as accurate as ever.
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