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TPU vs PVC
10 years ago
Hi Folks, while answering some questions recently, I wondered what others might think about materials of construction too:
So we all know that PVC (Poly Vinyl Chloride) is the typical material that all our lovely inflatables get made from. A while back, I bought some inflatable furniture from Fugufurniture.com, made from TPU (Thermoplastic Polyurethane). It was brilliant, clear, fold free and to my suprise, quite stretchy. So I investigate the differences a little further.
PVC is flexible, but in terms of physical properties, it's quite plastic and not very elastic, this means that if you stretch it, it won't go back to its original state (Plastic-deformation), also, if you crease it too much, the same again, the folds are permanent and it can damage the seams. TPU on the other hand is very tough and elastic, almost like a rubber balloon but a polymer. Unlike PVC, you can stretch it (within reason) and it will return to its original state (Elastic). I say within reason, actually, with thicker material e.g. 0.3 to 0.4mm you wouldn't be able to deform it (unless perhaps you happen to be the incredible hulk!)
If you compared the two materials together, TPU stretches where PVC would not. So instead of PVC placing a lot of strain on the seams when for example you jump onto an inflatable, TPU distributes the strain across its whole surface (it all stretches), so the seams see substantially less strain. This makes items made from TPU very long lasting when compared with PVC. The problem is that it's a lot more expensive to make items from TPU when compared with PVC. This is purely because it's not currently manufactured in such huge quantities as PVC (the more you make, the cheaper it gets).
(To Note: Fugu are so confident with the strength and resilience of their TPU material that they give a 1 year gaurantee on all their inflatable products - there's confidence for you!)
At some point in the future, maybe TPU will become more affordable, then our inflatables would last even better, stand up to heavier people, more punishment without splitting, but for now, it's PVC.
Sound interesting?
So we all know that PVC (Poly Vinyl Chloride) is the typical material that all our lovely inflatables get made from. A while back, I bought some inflatable furniture from Fugufurniture.com, made from TPU (Thermoplastic Polyurethane). It was brilliant, clear, fold free and to my suprise, quite stretchy. So I investigate the differences a little further.
PVC is flexible, but in terms of physical properties, it's quite plastic and not very elastic, this means that if you stretch it, it won't go back to its original state (Plastic-deformation), also, if you crease it too much, the same again, the folds are permanent and it can damage the seams. TPU on the other hand is very tough and elastic, almost like a rubber balloon but a polymer. Unlike PVC, you can stretch it (within reason) and it will return to its original state (Elastic). I say within reason, actually, with thicker material e.g. 0.3 to 0.4mm you wouldn't be able to deform it (unless perhaps you happen to be the incredible hulk!)
If you compared the two materials together, TPU stretches where PVC would not. So instead of PVC placing a lot of strain on the seams when for example you jump onto an inflatable, TPU distributes the strain across its whole surface (it all stretches), so the seams see substantially less strain. This makes items made from TPU very long lasting when compared with PVC. The problem is that it's a lot more expensive to make items from TPU when compared with PVC. This is purely because it's not currently manufactured in such huge quantities as PVC (the more you make, the cheaper it gets).
(To Note: Fugu are so confident with the strength and resilience of their TPU material that they give a 1 year gaurantee on all their inflatable products - there's confidence for you!)
At some point in the future, maybe TPU will become more affordable, then our inflatables would last even better, stand up to heavier people, more punishment without splitting, but for now, it's PVC.
Sound interesting?
You, me and our fellow inflatables experts know that when we take our friends out into the sunshine, the material goes softer and stretchier, this is where the energy of the molecules moving starts to exceed the forces attracting them together. (they get substantially more Squidgy and Huggable right ;0) )
Plasticisers are added during manufacture, when the PVC is heated up and in liquid state, they make their way (bond) between the PVC molecules, so when the PVC cools down again, it actually maintains the same flexibility and softness at lower temperatures. As you can imagine there is a "Sweet spot" for the amount of plasticiser used. Too little and the PVC will remain hard and inflexible, too much and you start to affect the mechanical strength of the polymer, so it becomes more likely to split and fail.
Production wise, the plasticiser and PVC are blended together rather than there being a chemical reaction, so it's very important to achieve good mixing between the two so you get this nice flexibility throughout the material.
Unfortunately, I don't think there is a way to retro-actively add plasticisers as you'd have to heat your poor inflatable up to melting point so it becomes liquid before these chemicals can be added.
Another important additive for PVC should always be some form of UV protection - we're very likely to take our inflatables out in the sunshine right, so you don't want them to degrade / break down while they are there. You can see this happen with certain products as colours start to fade with time.
Almost makes you wonder if you should put sun-tan lotion on your inflatable too - although that might make staying on quite difficult!
With regards other inflatables made from TPU, I currently only know of Fugu making furniture and bespoke inflatables. The ones I have are their Cubrik Chair, two Kuki Sofas and a Maki table - You can see these by downloading the catalog from their website (Fugufurniture.com) [They are a French company, based in Paris].
(To Note: from what I can tell, Fugu would still be the right people to go to for TPU inflatable construction as they have a lot of experience)
What is ATBC by the way? A repair service?
As for "How does it work" - I'm not entirely sure from a physical or chemical aspect.
Ideally, these plasticisers shouldn't break down / escape (They should be stable). But I wonder, could it be exposure to sunlight as this will degrade it - does your Dragon sit in direct sunlight for any period of time?
One thing that I did note is that your average spray polish is quite good for slowing the loss of plasticisers down, it's just making a thin layer of silicone on the surface which can help protect, to a certain degree, against abrasion too.
Silicone spray does do... something to a degree, but I don't like the smeary feeling it produces. You also need to make sure there is no oil in there what so ever.
And, yeah, fair point with the smeary feeling. Understand with the potential for leaching and reaction of oils though, yeah, always pays to check the contents first rather than paying the price later. Best to stick to unscented polish as the scented types are the ones that will contain these oily aliphatics.
So overall outcome for now - further investigation to follow. I'll let you know if I find anything else useful out too (maybe after the next time I chat with IW.DE).
PVC is inflexible, it is hard and brittle as a rock. Plasticizers make PVC flexible (and give of more or less nice odor).
PU is hideously expansive compared to PVC and while PVC is easily printable PU seems to be much much more difficult to print on. PU might also have problems with hydrolysis while it is the most "light-stable" polymer available it has weaknesses in the chemical stability compared to PVC.
PVC is the most cheap polymer that you can get, since its more or less a sink for chlorine for the chemical industry.