[alexanderdundua]

need ideas.
How would you distinguish weather your polymer is a pure copolymer or contains certain amount of homopolymer.
Extraction is not an option!

[typhoon2028]

Try DSC.

Homo and copolymer should have different melting points.

[alexanderdundua]

already on it; after glass transitions though. any other ideas?

[Enthalpy]

I suppose you know what the plastic family is, for instance polyoxomethylene and polyoxoethylene.

One excellent method is to measure the density then. On a cylinder or a brick, you measure the dimensions with 10^-3 accuracy at least, scales give you the mass at least as precisely. Since POM-H and POM-C differ by several %, you get a definite answer. Be careful with humidity absorption in PVC-PVA and in PA.

If you only have one object of this polymer, you might try to adjust a liquid mixture until the object just sinks in it. I haven't done it by myself; check for bubbles.

In the case of POM, you could pyrolyse it to determine what proportion of C makes the initial mass: big difference between -C-O- and -C-C-O-. Less huge with polystyrene copolymers and with polyamides, bad with polyolefins.

Then you have the low-tech methods, which require reference samples. Burn chips, compare the smells, the fumes, the flames and droplets. Or scratch the surface with a needle, feel the movement with your fingers. These are rather mechanics workshop methods, probably not what people expect from a chemistry lab.