Forgive me if I'm telling you something you already know, but the name POLYSTYRENE describes a polymer made from STYRENE. To a non-chemist, like me, the “POLY” bit [no parrot jokes, please!] simply means that the individual STYRENE molecules have been 'polymerised' into a series of long, chain molecules.

STYRENE itself, originally known as STYROL has a surprisingly long pedigree. It was first isolated by Eduard Simon, an apothecary from Berlin, in 1839. The source was the resin from the American Sweet Gum Tree [Liquidambar Styraciflua] - which is clearly where the “STYR” bit comes from.
When he returned to his sample a few days later, he found that the liquid had turned into a thick gel, which he assumed to be oxidation, but was eventually proven to be a modest natural polymerisation.
Apart from a few chemists 'playing' with the material, what is, with hindsight, a major commercial opportunity went begging for well over 80 years, until I.G. Farben, in Ludwigshafen, Germany, c.1931 began limited production of POLYSTYRENE.
Technically POLYSTYRENE is a synthetic aromatic polymer, the 'aromatic' bit is the term used for chemicals containing flat, 'ring-shaped' molecules with resonance bonds - that's chemist speak for the [near ubiquitous] benzene ring [the hexagonal component of the molecule at the top of the diagram, right].
Polystyrene formula diagram
The 'bracketed structure', with the “n” repeater, [bottom right corner] is the shorthand version to say that the whole thing is repeated in a chain [or polymer] “n” molecules [or monomers] long.
Basic POLYSTYRENE is clear, and glass-like, but, when heated to just beyond the boiling point of water, it becomes liquid and can then be easily injected into moulds to produce an almost infinite variety of items. Add a bit of colour and away you go!
Although some forms can be slightly more robust thermally, unlike BAKELITE [a thermoset plastic], POLYSTYRENE [a thermoplastic] is generally not good with heat. Pour boiling water onto any of BAYKO's POLYSTYRENE bricks or windows and you're unlikely ever to be able to build with them again…
…don't say I didn't warn you!!!
BAKELITE molecules link together in many directions rather than as a chain as in POLYSTYRENE, which accounts, in part, for its greater stability, all of which means that POLYSTYRENE has greater potential for recycling.
However, it's not all good news with POLYSTYRENE. Although much of it can be recycled, our general stupidity, and protracted response times, together with its relative longevity means that we now have plastic slicks and tide lines all over the planet, which, sooner or later, hopefully the former, we will have to eliminate. For the record, I wrote this paragraph long before that ingenue David Attenborough hove into view!
Plimpton era POLYSTYRENE components are made from STYRON, the British Resin Products brand name. [B.R.P. is a subsidiary of Dow Chemicals]. The relationship between the companies was obviously healthy, despite the perilous state of Plimpton's finances at the time, as the advert in 'British Toys', a leading publication for the U.K. toy trade, shows us. They were issued in in June, 1959, and again in September
Personally I'm not the world's most ardent fan of Plimpton era POLYSTYRENE, though I understand their quest for the resultant cost savings. I can't help but think that BAYKO's inventor, C.B. Plimpton, would have done it so much better - after all, Mr. MECCANO did!
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Latest update - August 11, 2022
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