Do not use PVC. It is too slick. It can also get pretty cold in the winter which might lead to foot damage if you are in a really cold climate. PVC can be pretty flexible too. It can sag under their weight.
Use wood. It is a great insulator as far as the cold goes and they can grip it well. It needs to be thick enough that it does not sag.
Some of us use tree branches. Some use various pieces of lumber. A real popular size is a 2”x4”, sometimes with the flat side up and sometimes with the narrow side up. Some use other sizes but I’d suggest you not go narrower than the 1-1/2” thickness. As long as their toes are they need a certain size to grip. If you use sawn lumber, smooth off the sharp corners. I use sandpaper. Some people think this makes it more comfortable on their feet but I do it to remove splinters. It doesn’t take much, just knock the sharp edge off.
Some people passionately believe one of these is better than any other. The problem is that all three have their supporters. Some people strongly believe the best way is a 2x4 with the flat side up. Others feel that the chickens are more comfortable with the narrow side up, that they can grip better. Then you have those that think tree branches are the most natural way to go.
I’ve tried all three at the same time. My chickens have told me that people care about this a lot more than chickens do. All three work fine.