Yes, but because plastic is an oily surface, we would suggest that you:
Step 1: Lightly sand the entire object, just to create enough of a rough surface area for the paint to hold.
Step 2: Clean well with Lacquer Thinners and allow to dry for 20 minutes. (refer preparation with Lacquer thinners).
3) Start painting.
4) If the object or piece of furniture is going to be outside, we would finish with a clear glaze which will protect it against the outside elements. (refer Clear Glaze application)