In relation to the surviving of rubber materials in pneumatic
instruments, one aspect does not appear to have been mentioned
and that is ozone.

Ozone, a 3-atom oxygen molecule, is a killer of rubber.  High
concentrations can cause the breakdown of rubber in minutes and
is easily generated by electrical sparks.  Every time I switch on my
Duo-Art upright there is some sparking from the centrifugal switch in
the original motor.  It is usually is accompanied by a characteristic
"electrical" smell that is associated with ozone and is reminiscent
of my childhood toy train set.

I am planning to try to reduce this spark with a suitable small
capacitor, but it would be difficult to remove the ozone entirely as
even without a spark, oxygen in the presence of any electrical machine
and alternating current will produce ozone.

Another source of ozone is city pollution.  It has been found that
rubber lasts for significantly less time in polluted areas. See
http://www.thcnet.com/downloads/techozone.pdf  Maybe this is why modern
rubber cloth and tubes do not seem to have the lasting qualities of the
original.  It is simply that we live in a more polluted world nowadays.

James Black