The 20th and 21st centuries have justifiably been dubbed the Plastics Age, such is the influence and ubiquity of this family of materials.
Plastics pervade all aspects of society. We sleep on plastic-filled pillows, clean our teeth with plastic toothbrushes, type on plastic keyboards, drink and eat food from plastic containers—it’s impossible to go through a day without encountering plastic of some kind.
But as we are becoming increasingly aware, our widespread adoption of plastics has not been without consequences to our health and the environment. Plastic pollutes our landscapes, oceans, air and bodies. It has even entered the fossil record.
How did we get here? When did plastics become the ever-present material of modern society? And what might be the answers to the environmental impacts of plastics?
What is plastic?
Plastic is a loose term for describing materials that can be formed and moulded under heat and pressure.
Polymers are the chemical class of materials that make up all modern plastics. They are large molecules, consisting of a chain of repeating smaller molecules (monomers). The process of combining these monomers (e.g. ethylene gas) by heat and pressure is called polymerisation.
The invention of plastic
While we think of plastic as a 20th-century material, natural plastics such as horn, tortoiseshell, amber, rubber and shellac have been worked with since antiquity.
Animal horns, malleable when heated, were used for many purposes and products, from medallions to cutlery. The comb-making industry was one of the biggest applications of horn in the 19th century.
The first synthetic plastics
By the middle of the 19th century, in the wake of industrialised goods production, some animal-derived materials had become increasingly scarce. Elephants were facing extinction if demand for their ivory, used in items from piano keys to billiard balls, continued. The same fate awaited some species of turtle, whose shell was harnessed for combs.
Inventors soon attempted to tackle this environmental and economic problem, with many patents for new semi-synthetic materials based on natural substances such as cork, blood and milk. One of the earliest was cellulose nitrate—cotton fibres dissolved in nitric and sulphuric acids then mixed with vegetable oil.
Its inventor, the Birmingham-born artisan-cum-chemist Alexander Parkes, patented this new material in 1862 as Parkesine. Considered the first man-made plastic, it was a cheap and colourful substitute for ivory or tortoiseshell.
Parkes himself didn’t enjoy commercial success—but his invention did, taken up and developed by others, including his former factory manager Daniel Spill and the businessman John Wesley Hyatt, the latter of whom founded the Celluloid Manufacturing Company in the US.
This new plastic made items like combs and billiards affordable to many more people, democratising consumer goods and culture.
Undoubtedly, celluloid’s greatest cultural application was cinema film. Ironically, as movie stars made short hair popular in the 1920s, the celluloid comb industry was short-lived—until manufacturers switched to making a newly fashionable product: sunglasses.
The rise of a plastics industry
The 20th century saw a revolution in plastic production: the advent of entirely synthetic plastics.
Belgian chemist and clever marketeer Leo Baekeland pioneered the first fully synthetic plastic in 1907.
He beat his Scottish rival, James Swinburne, to the patent office by one day. His invention, which he would christen Bakelite, combined two chemicals, formaldehyde and phenol, under heat and pressure.
Bakelite sparked a consumer boom in affordable, yet highly desirable, products. It had a dark brown, wood-like appearance but could be easily mass-produced, making it ideal for bringing new design trends such as Art Deco to the masses.
Some products became 20th-century icons: the Purma camera, the GPO telephone and the Ekco AD36 radio.
In the early decades of the 20th century, the petroleum and chemical industries began to form alliances in companies like Dow Chemicals, ExxonMobil, DuPont and BASF. These companies are still the major producers of raw material resins for the plastics industry today.
These alliances were driven by the desire to make use of waste material from processing crude oil and natural gas. One of the most abundant of these was ethylene gas, a by-product which the British company Imperial Chemical Industries (ICI) beat its German and US competitors to make a plastic from.
Formed in 1926, ICI had its first big plastic success with Perspex in 1932.
The following year, a team at ICI’s plant in Winnington were attempting to combine ethylene and benzaldehyde under great pressure and heat. The experiment failed. Instead, due to a leak of oxygen into the vessel, they found a white waxy substance in a reaction tube.
This was found to be a polymer of ethylene. Now the world’s most abundant plastic, polyethylene was a wonder material: strong, flexible and heat-resistant.
Its first application was insulating radar cabling during the Second World War, but consumer products soon followed, from the plastic shopping bag and Tupperware to artificial hip and knee joints.
When did plastics become an environmental problem?
The chemical properties that have made plastic an incredibly useful and durable material also make it difficult to dispose of, with some types taking thousands—even tens of thousands—of years to degrade in landfill.
The degradation itself is an even bigger environmental issue, as the breaking down of plastics into microscopic particles pollutes our ocean, air and ecosystems. The health implications of microplastic deposits in our bodies are not yet fully known.
Many of our plastic problems began in the post-war period, when plastic began to replace the more expensive paper, glass and metal materials used in throwaway items, such as consumer packaging.
Among the worst offenders, along with polyethylene shopping bags and polystyrene food containers, is the PET (polyethylene terephthalate, a form of polyester) drinks bottle.
First patented in 1973 by American entrepreneur Nathaniel Wyeth, the PET bottle has many advantages over glass: lightweight for transport and safe in that it’s virtually unbreakable.
The PET polymer was developed specifically to contain pressurised carbonated drinks, though its popularity as a container for still beverages, above all water, has boomed in the 21st century.
The economics of mass-produced, cheap plastic products have led to a single-use culture, and today around 500 billion PET bottles are sold every year.
This figure is increasing, and the majority of these bottles end up in our oceans, degrading into microplastics.
Can chemists solve the plastic problem?
Since the modern plastics industry relies on fossil fuels for its raw material, the production of plastic has an impact on climate change, contributing to global C02 production.
For several decades, chemists have researched and developed 'green' plastics, which—like early semi-synthetic plastics—are derived from natural, biological material such as corn starch.
ICI, the British innovators of polyethylene, developed the first practical biodegradable plastic, Biopol, in 1990, which was first used in a Wella shampoo bottle.
But not all bioplastics are better in terms of disposing or recycling.
These materials are becoming increasingly common in single-use packaging. But biodegradable plastics are only recycled if they end up in adequately compostable waste—domestic composting is not usually up to the job.
One of the biggest barriers to plastic recycling is separation: when different polymers are mixed, the resulting material does not usually have useful properties. Even two PET items, a drinks bottle and cookie cutter, for example, may have different melting temperatures that produce an unusable sludge when combined.
At the moment, chemical means of sorting plastics like spectroscopic analysis are not economically viable on a big scale, so it’s down to human sorters to do the job.
The PET bottle, which has a number 1 triangular recycling code, is one of the most recycled items in the world. Clothing is one use for recycled PET polyester, initially made popular by Patagonia fleeces.
Recycled plastic items have even become marketable and fashionable in the 21st century era of increasing environmental consciousness, where the original use of the material is often named on the product.
The solution to the plastic problem will be a social and political one. Rather than relying on a technological fix, we must improve recycling infrastructure—so little is recycled, and there’s already enough plastic on the planet that we should stop producing it in vast quantities.
But the key will be moving away from single-use plastic altogether. Suppliers such as supermarkets need to do more. And culturally, we should be inspired by the early plastics industry—where beautifully designed combs, radios and telephones were desirable products that you valued and kept.
Find out more
- Science Museum blog, Teflon: 80 years of not sticking to things
- Science Museum blog, Nylon: The creation of a revolutionary fabric
- Scientific American, A Brief History of Plastic's Conquest of the World
- The Atlantic, How the Plastic Bag Became So Popular
- The Guardian, Plastic Recycling is a Myth: What Really Happens to Your Rubbish
- Susan Freinkel, Plastic: A Toxic Love Story, 2011
- Susan Mossman, Fantastic Plastic, 2008