nope. low density polyethylene. when exposed to sunlight it breaks down rapidly into hydrogen carbon, co2 and dust.
the "garbage island" story is a fabrication. if you sailed through "garbage island" you would likely see no trash at all.
the pacific gyre (the number one cited "garbage island") contains mostly microscopic decomposing plastic particles.
the atlantic gyre is actually easier to see, because of all the sargassum. but sargassum isnt pollution, and thus the atlantic gyre doesnt elicit terror among the easily baffled.
interestingly, the "garbage island" in the pacific required numerous boats sieving the ocean to get any substantial trash. larger and more bouyant stuff is often kicked out into the currents and makes landfall.
like the Nike Tides in washington state.
www.msc.ucla.edu/oceanglobe/pdf/nike_invest.pdf