I'm researching the degradation of polyethylene (PE) plastic films such as in plastic bags, and am trying to figure if they degrade chemically. If so: under what conditions, and into what byproducts. Most sources for PE say that it is inert, but it seems to be referring to the pellets used in manufacturing rather than the film/end product. I don't know if surface area has a significant effect here.
I know they mechanically break down (fragment) due to heat, sunlight (UV), physical stress, etc. Does anyone know how small these fragments can get and if they can be moved through water (possibly a separate question).
My question is about either high- or low-density PE.
For more context, see: Removing agricultural plastic film waste after 10+ years degradation