[Trent B]

Just doing some rudimentary comparisons with CES EduPack (materials database).

PP seems to generally have higher impact toughness (absorbs more energy when fracturing) than PVC but is slightly lower yield strength. Tensile strength differences are pretty marginal.

Probably the biggest draw for PP over PVC is the comparative glass transition temperatures, PP is below freezing while PVC is nearly the boiling point of water. This is a reversible transition that is accompanied by a change in elastic modulus (stiffness), addition when above this temperature the polymer should be more ductile which correlates with PP taking more energy to fracture.