[elsa]

I am comparing two polymeric tarpaulin materials, that should be the same (they have a lot of similar characteristics like color, size, elemental composition etc.). I did a FTIR analysis that said that both of these materials have polyethylene and CaCO3 in them, but one of the materials consistently shows peaks at 1539 and 1575cm-1, could they have originated while being held in poor conditions (one of the tarpaulins was held in a ditch for a long time), or is that just a difference in production batches?

[marquis]

It sounds like most of the ingredients have been covered.  The one ingredient not totally covered is Polyethylene.  The one warning about polyethylene.  There are many varieties( high density, low density, different molecular weights, different branching structures, etc.).  Most routine testing will not show these differences.  If further testing is required, you might investigate something like gel permeation chromatography(GPC). Because it's PE, it has to be done at something like 160 C with some not so nice solvents. Good luck.