Depending on the nature of the products (whether crosslinked or non-crosslinked) extraction by solvent may be a solution. By the way your description of the experimental situation is not fully clear. Do you want to see biodgeradation products of PP?

We have put PP beads in contact with bacterial suspension and we want to detect a potential degradation on the surface of the beads. We do not know which products are created, but we would like to extract them to characterize them by NMR. So we need an optimal method for the extraction of bio-degradation products.

I am not a specialist in this field, but I wonder how do your discriminate the degradation products of PP from the excretion products of the bacteria themselves? How do you want to characterize a mixture of products by NMR if you do not separate the products form each other? I would rather suggest e.g. to perform a comparative MALDI-TOF study of the supernatant of the bacterial culture itself in comparison with that of the bacterial culture + PP. Do you have special bacterial strains which are expected to attack the PP surface? Normally bacteria cannot attack polyolefin surfaces directly. I believe it would be more meaningful to study the changes in the surface structure of PP (e.g. by SEM) after exposure to bacterial culture and washing. It can tell you whether any morphological change can be observed.