The Mysterious collapsing Lucozade Bottles..!
A scientific investigation of a curious phenomenon.....
I occasionally drive a Ford Transit van for some friends in a band, and after a long, hard day, sometimes feel
the need to partake of a refreshing sugar-rich soft drink to quench my thirst and keep
alert for the drive home. The resultant empty bottles tend to get discarded on the
dashboard, and have accumulated in the area between tyhe dash and the windscreen.
Over a number of months I observed that some of these empty bottles have collapsed, as
shown above. I was curious as to what was causing this effect, and initiated the following
Inside the windscreen of a Ford Transit van (K-Reg, diesel, Blue). The
interior can get quite hot in summer, and this may help soften the bottles, so the
internal pressure is typically close to atmospheric. Squeezing the bottles appears to
The presence of Bill the Monkey (left) is not considered to be a significant
The displacement volume of the bottles was measured by immersion in
a cylindrical water vessel. The results are as follows :
||Sell-By date 2
||Percentage volume remaining
|1 (not collapsed)1
|5 (not collapsed)1
1) The non-collapsed bottle samples 1 and 5 were probably the result of the cap not
being tightly closed. These were used as the reference for the percentage figures.
2) As no data is available on the length of time that the collapse takes, the sell-by
dates are recorded as they may give a very approximate idea of this, however as this is
heavily dependent on uncontrolled variables such as shop stock rotation, it should be
regarded as being of little or no use.
It would be interesting to analyse the composition of the gases remaining
in the collapsed bottles, in particular Nitrogen, Oxygen and Carbon Dioxide. If anyone in
the UK has access to a suitable gas analyser I'll happily send a bottle for analysis!
If it is assumed that the lowest figures above are the ultimate values, and little or
no further shrinkage occurs, then the amount of shrinkage corresponds quite well to the
percentage of oxygen in the atmosphere.
The amount of collapse is far to high to be due to barometric pressure variations.
Some process is clearly ocurring in the bottles, which is causing a change in the
internal pressure. My best guess is that it is either :
1) A chemical reaction involving the remnants of Lucozade, the plastic, air, and the lid
2) A biological process, bacterial contamination occurring during the drinking process
making use of the very sugar-rich Lucozade remnants to convert the air inside.
Any useful suggestions on the exact
explanation are welcome! Any further information will be added to this page.
The phenomenon has also been seen in Mars Drink and Drinking Yoghurt bottles.
Many people have suggested a mechanism based on the cap acting as a one-way valve with
heat fluctuations. I'm not convinced of this as the caps are screwed on tightly.
Others have suggested that it is a heat-shrink effect of the sleeve. This is not the
case as the bottles return to their original shape when the cap is removed.
From: Robert J. Furmanak :
I have a possible explanation, derived from my experience with polymers. One thing
about polymers, they all pass water, over time a soda bottle will "sweat" all of
the moisture out of it. Perhaps this is what is happening to your bottles, a small amount
moisture remaining has escaped, reducing the pressure in the bottle? I would suggest
repeating your experiment with a thoroughly dry bottle.
From: Goncala Gamboa :
With regard to the mysterious shrinking bottles, I may add that I have observed this
effect plenty of times in my lab (I am an organic chemist). The effect is most evident in
our 2 litre low density polyethylene bottles containing acetone. After using the acetone
we often keep some of these bottles for a while as they are convenient for short term
storage of solutions. Anyway, most times they are stored with some residues of acetone and
after a couple of weeks most of them will have shrunk quite a bit. It is my opinion too
that what happens is an oxidative process that consumes most of the oxygen in the bottle.
The acetone must undergo some sort of oxidation. In your lucozade bottles the same must be
happening. Glucose, one of the components of lucozade, has an aldehyde group that easily
gets oxidized to a carboxylic acid, consuming oxygen. That would explain the circa 20%
reduction in volume. The same explanation probably could apply to the Mars and Yogurt
drinks. Even if they don't contain nearly as much glucose as lucosade, they surely have
some other oxidizable substrates. It would be interesting to check if an
oxygen-enriched atmosphere lucosade bottle would shrink more than 20%. If you are really
interested, you can prepare some O2 by decomposing hydrogen peroxide (the sort you use to
clean wounds, 3-6%) with some catalyst such as MnO2. The MnO2 can be taken from a used 1.5
V normal (not alkaline) battery. Instead of MnO2 you could simply use a little bit of cow
liver as it contains plenty of catalase that will catalyze that reaction. In any case,
take care handling the chemicals and don't enrich the bottle with too much O2 as you don't
want the oxidation to be "too intense" and risk blowing the bottle or something
like that...Hope this helps!
From Richard Jordan : My dad has worked in the plastics industry for all his
career, and he was
always been describing the properties of plastics to me as a kid. All plastics are
permeable to some degree to the smaller molecules of air. If those lucosade bottles were
heated by the sun, the pressure differential created inside would very slowly force the
smaller of the air molecules (hydrogen) out of the bottle through the plastic. Upon
cooling down, the pressure differential would disappear, forcing the bottle to collapse in
on itself. The bottle therefore is acting as a partially permeable membrane. In theory,
the force of the bottle trying to reexpand would not be enough to force the molecules back
the other way. Anyway, just a theory.
Another contributor : PET (polyester) is used in soft drink
bottles because it has a very low permeation rate for CO2. This allows for a fairly long
shelf life before the bottles go flat. The permeation rate for CO2 in PET is about 2-3
times that of oxygen (the permeation rate of N2 is even lower). The driving force for
permeation of a gas is not the absolute pressure difference between the two sides of the
membrane, but is the partial pressure difference for the particular gas. If the inside of
the bottle has a high concentration of CO2 in it, this CO2 will move (permeate) from the
inside to the outside to try and equalize the partial pressures inside and outside the
bottle. The oxygen and nitrogen outside the bottle will try and do the same but at a
slower rate. Raising the temperature of the bottle will increase permeation rates. You can
verify this by taking one bottle and leaving it on its side opened for a day before you
cap it. This will be the air filled control. Take the upright test bottle and put a little
chunk of dry ice in the bottom and let it evaporate. Immediately after the dry ice has
evaporated, but not before, cap this bottle. This will be the CO2 filled test bottle. Put
both bottles in the test chamber (between the dash and windscreen) and watch for results.
The peculiar final shape of the bottles is due to the stresses induced by the blow-molding
process used in making the bottle. At higher temperatures the PET will try to change shape
to reduce these stresses.