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Burning bras ?

Dear Reader,

It has come to my attention that Gwyneth Paltrow now suggests that ladies should ignite underwear and bras which were given to them by ex-lovers at night in the light of a full moon. To my mind it is the height of sillyness. What about the negative effects on them if they manage to spark a forest fire or even just a fire which wipes out next door’s garden. Trust me I would be mad with rage if someone near me wiped out my garden with their midnight bra burning ritual.

But as a man who likes to be inspired by the likes of “Don Myers G8AYG” who was accused recently by one Prof I know of having been a “Real scientist”, I refuse to be intimidated by even the greatest nonsense in life. I hold the view that I have a duty to society as a whole to call out nonsense and to point out pseudoscience. I also noticed that Gwyneth has a lingerie shop, so adding a new dimension to the matter.

If women destroy lingerie then they will need to buy more to replace the burnt items, anyone who owns a lingerie will have the potential to make more money if women burn lingerie which they own.

I would like to point out something that rather than “Watch intently as the pieces burn. Know that your past is recycling into the ethers, liberating your future.” (step four of her bra burning ritual) you are polluting your lungs and the common air with polycyclic aromatic hydrocarbons, soot, carbon monoxide and other nasties. Also you will be releasing carbon dioxide which is a greenhouse gas.

I would also like to point out that todays bras are not designed for burning. Now most mornings on my way to work I walk past a shop (Hunkemöller) which sells ladies underwear. Trust me I am in too much of a dash to get to Chalmers to experience the joys of working in IMR / KK to stop and look at the shop yet alone wait for it to open in the morning.

Sadly I do not think that a bra comes with a detailed list of the polymers inside it or information on what will happen if you burn it. I think that the average customer is more interested in wearing them when they buy them rather than thinking about burning them.

After considering the idea of burning a bra I wondered what sort of fabric it might contain, rather than going to somewhere like Hunkemöller and then having to get pyro-GCMS done on many samples from the items. I have chosen to do some guesswork. The first thing I wondered about was lycra. It is a combination of polyether and polyurethane. As polyurethanes are very nitrogen rich I have to consider if the combustion is rich rather than being lean it might form hydrogen cyanide.

Also we should consider the larger organic products of heating lycra, I have checked the literature (Sandeep Khatua and You-Lo Hsieh, Journal of Polymer Science A, 1997, 35, 3263) and one grade of Lycra is made from the polyether made from butane-1,4-diol (Mn = 2000) and diphenylmethane-4,4′-diisocyanate (MDI) which is then chain extended with ethylene diamine (1,2-diaminoethane). This is a polymer product which has soft sections (the polyether) and the other part (PU) is the hard part of the product. As the product is largely this soft polymer I choose to first consider the degradation of this soft part. I could not see the potential for the formation of anything which screamed “nasty” at me.

So I choose to consider the hard part of the plastic, I checked the literature and with the first paper I found a nasty. J.J. He, L. Jiang, J.H. Sun and S. Lo in / Journal of Analytical and Applied Pyrolysis 2016, 120, 269–283 indicated that during the pyrolysis of a hard polyureathane which has similar chemistry to the lycra grade I found that aniline and other aromatic amines were formed. I can tell you that these aromatic amines are unhealthy. So as a chemist I would advise you not to burn lycra under uncontrolled conditions where you can not be sure that an excess of oxygen will be present.

If any of my readers know that a bra or some other item contains a particular polymer then please contact me, I can have a go at considering what will happen if we heat the polymer to the point at which it starts to degrade chemically.

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