Owen wrote:
. . .
Polypropylene is also resistant to mild acids (and alkalis), but it is
a slippery (greasy) rope that doesn't hold knots or splices as readily
as natural fibre ropes.

Polypropylene deteriorates rapidly from the UV in sunlight. Here in
western Oregon it'll last a couple of years before seriously weakening,
but in Denver (mile high and lots of sun) it turns to little more than
powder in about six months.

Roy Lewallen, W7EL