Hi Don,
I don't believe there are any "breathable" plastic pants or rubber pants for that matter....tho the impression of comfort is a whole different thing with some folks reporting plastic pants feeling cooler than rubber pants and vice versa.
But for actual breathability you need to look to coated fabric pants. One of the first I tried and still like very much is Duraline's Dura tex waterproof pants. Find them at
www.dmponline.com I think they are still reasonably priced and are certainly thin and comfortable.
Kins also offers two pants that are breathable, a light thin nylon pant, #10300 and a slightly heavier version, called mid weight, polyester pant, #10200.
The breathable waterproof pants when worn over cloth diapers will develope a damp clammy feel as the cloth diaper gets wet but under most circumstances will not allow enough moisture thru to create a wet spot on your outer wear. Since you wear disposables, that won't be a factor at all. Try the lighter pants first and if they are what you are looking for and want something more rugged, try the Kins polyester.
I believe Euroflex is a Gary Mfg'g term for urethane pants. The majority of plastic pants are vinyl (PVC) but urethane (polyurethane) is a great plastic for making pants as it is stronger than vinyl and highly resistant to oils in rash creams that cause vinyl pants to stiffen and become uncomfortable to wear. In your case with fecal incon you most likely are going to want to use a rash cream (like Desitine) liberally as a preventative measure to shield your skin from the caustic digestive acids that are in stool. Urethane pants are a much better bet for you in that case. And, urethane is the material most often used to waterproof fabric pants...the nylon and polyester pants we mentioned earlier.
The difference between urethane plastic pants and the treated waterproof pants is the plastic pants are not breathable but the fabric pants are, due to the thread of the nylon or polyester pant being treated with urethane...makes the pant pretty much waterproof but with tiny spaces between the woven threads to allow breathing.
Good luck and good for you to plug ahead with school and not let incon get in your way!
JoeK