Any thoughts on how to identify which HDPEs have those things as a regular consumer, without mass spec? I'd assume they add those to get specific properties for

Any thoughts on how to identify which HDPEs have those things as a regular consumer, without mass spec? I'd assume they add those to get specific properties for specific applications and knowing the application and/or that an expert could tell from simply looking at or feeling the material? This is stuff hard to figure out as an academic, because it seems to be mostly internal industry knowledge.