The new cortex totally different - and for the old version I never saw any claims than what it was - plastic polymer added to help dampen vibration.
I'm a big guy and hit hard and at 6' 2" / 188cm and at 51 playing for almost 45 yrs.......I have NEVER seen frames just breaking. Ive seen frames restrung over and over stress crack but not because he frame are fragile. They are not designed to be tossed, thrown or bounced on the hard ground period. When you factor in the pressure of stringing and constant tension - even what you think is a light toss any frame will crack........I play at the 5.0+ level and ITF Sr events and see TONS of strong players hitting huge and they have NEVER broken a frame (Babs or otherwise) - the constant BS that Babolats break or manufactured cheaply total crap.........rant over.