Now that I think of it, I've been using polyurethane tubing for all my pneumatic projects (which have been many) and not a single hose has ever aged the way those chains did... perhaps their production process is of a far higher quality, or is the material being used substantially different?
Another thing I noticed, is that when I built my etching tank (more on that on a future thread) I once tried to use that same tubing to blow bubbles in the ferric chloride solution and the thing cracked and disintegrated in the course of a few days! why is that? The tank itself is made of acrylic and is unaffected by FeCl3 but what part of the polyurethane is it attacking? It wasn't until I used vinyl tubing that the thing more or less resisted the FeCl3, but it's not immune to it like acrylic... it's also attacked by it and cracks after a couple of years.
Another thing I noticed, is that when I built my etching tank (more on that on a future thread) I once tried to use that same tubing to blow bubbles in the ferric chloride solution and the thing cracked and disintegrated in the course of a few days! why is that? The tank itself is made of acrylic and is unaffected by FeCl3 but what part of the polyurethane is it attacking? It wasn't until I used vinyl tubing that the thing more or less resisted the FeCl3, but it's not immune to it like acrylic... it's also attacked by it and cracks after a couple of years.