| MadSci Network: Chemistry |
Styrofoam is the brand name Dow Chemicals use for extruded polystyrene foam, which is made in different densities for different applications. Your question relates to the type used in home insulation (as opposed to the type used for example, to make disposable drinking cups). Nowadays the gas used to foam the polymerising styrene is usually nitrogen whereas it used to often be CFC’s (chlorofluorocarbons), but these damage the ozone layer and are no longer used. This is good, as this in turn will yield fewer toxins when the polystyrene burns. In a typical house fire, there will be a range of combustion temperatures – this being key to the combustion products generated – and there may be particulates, styrene monomer (toxic) as well as the expected carbon monoxide (toxic) and carbon dioxide (not so toxic, but which if excluding oxygen, will kill). All of this sounds bad, but compared to what? Burning wood produces toxic fumes, smoke and a variety of toxic and non-toxic gases and from the MSDS (Materials Safety Data Sheet) I found below, it is suggested that polystyrene foam combustion would be no worse in toxic products produced than wood. Cyanide (in the form of hydrogen cyanide or HCN) – is not a likely combustion product of any significance. See the MSDS I found at: http://www.glasscellisofab.com/sheets/polystyrene/msds/styrofoam_ms ds.pdf - where you will find the following statement: - “Upon burning the product generates dense black smoke with small amounts of hydrogen bromide, -chloride, and -fluoride. Studies have shown that the products of combustion of this foam are not more acutely toxic than the products of combustion of common building materials such as wood.” This particular statement implies that in this example, halogenated gases are used in expanding the polystyrene – and yet the consequences of combustion are claimed to be no worse than burning wood. Fiberglass is a less well defined material as the glass is reinforcement to a polymer based resin material, and it is the combustion of the resin that will be the issue in making a comparison. Here is one MSDS regarding a fibreglass product; http://www.unisub.com/worldof/Tips/pdf-word/MSDS-FR% 20Plastic%20Unisub.doc However, different manufacturers will have different resins with somewhat differing combustion products. This one suggests the combustion products “are expected to be primarily aldehydes, carbon monoxide, and smoke.” So, it is not possible to give a definitive answer to your question – because it does depend on the constituents of the fibreglass resin, but you are almost certainly no worse off by the switch from fibreglass to polystyrene, and possibly better off. This is certainly not an issue you should lose any sleep over; there is no chance you will be poisoned by cyanide gas as a result of a neighbour’s house going up (at least as a consequence of his insulation), and if I were to hazard a guess, (pun intended) you are much more likely to suffer an early demise in that event by your own house going up in sympathy, while you sleep. Talking of which - flammability comparisons between the two insulating materials is another issue... Thanks for the question, and I hope you sleep easier as a result of my answer!
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