You are making this overly complicated.
Isotactic PP canned be changed to atactic unless it is depolymerized (can this even be done?) and then repolymerized (with the appropriate catalyst). If you want atactic, start with atactic.
Not that you would want atactic PP. It is a very soft plastic used as an adhesive base (pressure sensitive adhesives), barely being more aggressive than your typical Post-it note. You cannot repair a hernia with it.
PP mesh can be made a number of ways: there are 3 different die setups for extrusion (followed by possible orientation)
or it can be crosslaid and fused. I'd go with the latter as the resulting nonwoven is flatter and can be smaller diameter.
Stay away from free radicals when you have polypropylene in play, so that means no gamma radiation, no peroxide and no e-beam either. It just chews up the chains and leaves you with dust (although if you go far enough with it, I guess you could use it to depolymerize isotactic materials!) Steam is iffy. You might get by, you might not. It all depends on the processing conditions used in the manufacture of the mesh (and possibly the fiber manufacturer is you go the cross-laid route). ETO is your surest route.
John Aspen Research, -
"Turning Questions into Answers"
Opinions expressed herein are my own and may not represent those of my employer.