Probably not - the plastics harden are a different type with different properties. The industry was burned with early plastics that did have problems and is paying attention to this. PE has been used in plumbing for more than 50 years with no problems, PEX should last even longer.
Assuming you follow directions of course: PEX has zero UV resistance and if exposed to the sun for a couple months will break down and be useless.
Assuming you follow directions of course: PEX has zero UV resistance and if exposed to the sun for a couple months will break down and be useless.