It really doesn't matter what object or material your concerned about, the sun will eventually break it down. Unless it's made of concrete. It will eventualy do damage.
My daughter left her dept. store tent set up in the back yard for 2 months last summer and the sun basicly destroyed it. So that was done in basicly 60 days or so. Better coatings etc will prolong that time and weather did play a part in the destruction.