I am doing a study of this type of sonobuoy
(http://www.manlysource.com/sonobuoy/sonobuoy.htm)
Can anyone tell me what are those sonobuoys made of? 
I want accurate percentage of each element.  
The information about these sonobuoys are found here:
http://sonobuoy.crane.navy.mil/SENSORS.HTM

A lot of what sonobuoys do and how they do it is classified. I would
expect the details of their materials to be similarly classified.

The statement in the article that made me snicker was "The now empty
Sonobuoy Launch Container remains with the aircraft and is properly
disposed or recycled upon aircraft landing." I had friends on subs
that used them to make low fences, walkway borders, and doghouses. I
suppose that's proper recycling.

Suppose that the materials to be classified. 
What do people do after those expensive sonobuoys were disposed,
besides using them as fences, walkway borders?
What will be the most effective ways to recycle them?