History of Polystyrene (PS) and Styrofoam
Eduard Simon (GE) discovered PS in 1839 by distilling a monomer from a sweetgum tree resin and named it styrol. Styrol thickened into a jelly after a few days. Simon believed it was the result of oxidation and named it “styrol oxide”. John Buddle Blyth and August Wilhelm von Hofmann (GE) reached the same reaction in 1845 without oxygen and named it “metastyrol”.
Berthelot (FR) discovered in 1866 that the transformation of styrol into metastyrol / styrol oxide was the result of a polymerisation process. Polymerisation is the transformation of a monomer molecule into a kind of 3-dimensional chain (a polymer chain).
The name Polystyrene came from poly(mer) + styrol. Polystyrene is, technically speaking, a synthetic aromatic hydrocarbon polymer made from the monomer styrene. Polystyrene was first commercialised by IG Farben in 1931. Dow Chemical invented a Styrofoam process (expanded polystyrene EPS foam) in 1941 and trademarked the brand Styrofoam.
The key difference between expanded (EPS) and extruded polystyrene (XPS) is that EPS is produced from solid beads of polystyrene XPS is produced using solid polystyrene crystals.
Advantages, Applications and Sales of Polystyrene
PS has many advantages. It’s inert (doesn’t react with other materials), cost-effective, long-lasting, energy absorbing, sound dampening, mouldable, aesthetic, insulating, keeps food fresher longer, water resistant, solid, transparent and easy to sterilise.
Most popular applications include: appliances (refrigerators, AC, ovens, microwaves, etc.), automotive (instrument panels, door panels, child protective seats, etc), electronics (televisions, computers and IT equipment), foodservice, insulation (building walls, roofing), medical (test tubes and medical devices), packaging (CD and DVD cases, foam packaging peanuts for shipping, food packaging, meat/poultry trays and egg cartons).
These are mostly end-user applications so there must be a direct correlation between economic growth and PS sales volumes. The higher the disposable income that can be spent in cars, houses and takeaway food, the higher PS’ turnover.
The two most important factors that influences PS prices are the price of oil and PS production capacity.
Collection, Recycling and Biodegradation
PS is usually not collected separately and thus not recycled. PS is hard to recycle, and there are no investments to do so because there are no incentives. Financially speaking, PS has no intrinsic value; it’s too cheap to produce. Practically speaking, PS is too light and too voluminous to constitute a valuable waste stream.
Polystyrene cannot biodegrade. However, there are a few exceptions. Some kind of mealworms can eat polystyrene and it will degrade in their guts. Some kind of bacteria (Pseudomonas putida) can convert styrene oil into biodegradable PHA.
Health Hazard and Pollution
Polystyrene is made from benzene and styrene and both are carcinogens. 25 billion polystyrene cups are thrown away annually in the US. PS breaks down in little pieces when exposed to the sun (photo degradation) and PS foam particles are harmful to fish and other wildlife.
Polystyrene Bans
Many businesses are banning polystyrene. However, one must differentiate between Polystyrene (PS), Expanded (EPS) or Extruded Polystyrene (EPS).
Dunkin Donuts announced it will eliminate polystyrene foam cups entirely by 2020 and McDonald’s will eliminate polystyrene by the end of 2018.
China banned expanded polystyrene takeaway containers and tableware in 1999. However, the ban was not strictly respected and in 2013 the ban was lifted.
More than 100 US cities in 11 states have passed legislation prohibiting PS foam including NY city, Washington DC and Miami Beach. San Francisco banned styrofoam in 2016.
The future of EPS in the EU will be set by the new legislation on plastics that harm the environment. Banning PS seem to be inevitable. US is banning PS so it would be almost unimaginable if PS survives the new EU legislation. PS may probably die hard as the financial interest are huge and the lobbying armada may be set into motion to save PS.
Replacement of Polystyrene
The best way to understand the implications of banning and replacing PS is looking at its advantages. It won’t be easy because PS is a blockbuster.
Banning PS will not solve all the problems. End-of-life and waste management options should be considered when replacing PS otherwise we just replace one evil by another.
The only way to replace PS is through bans because PS is very cheap and no alternative material can cost-effectively compete with PS. Other ways to promote alternatives is through green public procurement schemes, lower VAT, tax shelter for investments, etc.
One of the most adequate material to replace PS is PLA. PLA is more expensive than PS because supply is limited. There’s only one large producer: NatureWorks. However, Total Corbion is building a PLA factory in Thailand and it will soon be operational.
Bio-polystyrene or drop-ins as they’re called in the profession, are polystyrenes made from renewable or biobased resources. These will face the same end-of-life issues as oil-based polystyrene.
Polystyrene Producers and Brands
Largest PS producers include:
- Alfa Alpek (Styropek)
- BASF (Styropor)
- Cellofoam
- Dow
- ENI
- Ineos
- LG Chem
- Total
- NOVA Chemicals
- Resirene
- Sabic
- Saudi Polymers
- Styrotech
- Trinseo
Closing Remarks
There may be a confusion between PS, EPS and XPS especially in the case of “plastic bans” because all these three options are commonly referred to as polystyrene by the wider audience. The foamy fast food packaging or foamy material used to wrap breakable goods is Expanded PS (EPS) also known by its trade mark Styrofoam. The transparent plastic cups used with water fountains in many offices are made from PS. Both PS cups and EPS containers are considered single-use packaging because they’re not recycled.
A good example to describe the complexity and ambiguity of banning EPS styrofoam is the following: unwrapping Christmas gifts. The first thing parents do when their kids unwrap Christmas gifts is to remove the styrofoam (EPS) from their hands otherwise the whole room is full of EPS particles and it’s a hustle to clean up. Imagine what million of tonnes of EPS do to the environment and ocean? On the other hand, breakable gift wouldn’t make it in one piece without EPS.
Can you imagine how harmful EPS must be that even China banned it in 1999. China?? 1999??