Pressure sensitive adhesives comprising propylene-ethylene(-diene) copolymers

A pressure-sensitive adhesive may comprise: about 18 wt % to about 90 wt % of a propylene-ethylene(-diene) (PE(D)M) copolymer; about 10 wt % to about 65 wt % of a tackifier; and 0 wt % to about 40 wt % of an oil. The PE(D)M copolymer may comprise: (a) about 60 wt % to about 99 wt % propylene, (b) about 1 wt % to about 40 wt % ethylene or a C4 to C22 alpha-olefin, and (c) 0 wt % to about 20 wt % diene, wherein the PE(D)M copolymer has a heat of fusion of about 15 J/g or less.