A novel evaluation method for biodegradability of poly(butylene succinate-co-butylene adipate) by pyrolysis-gas chromatography

Biodegradation behavior of poly(butylene succinate-co-butylene adipate) (PBSA) film samples during the soil burial degradation test was studied by pyrolysis-gas chromatography (Py-GC). In the pyrograms of the PBSA film sample residues, various ester compounds containing succinate and/or adipate units were observed as the main pyrolysis products along with some minor pyrolyzates such as fatty-acid esters comprising propionates and valerates which might be formed mostly from carboxyl end-groups existing in PBSA molecules. Although the relative yields of the major pyrolyzates were almost unchanged before and after the soil burial test, those of the fatty-acid esters decreased with the soil burial time almost correlating with the decrease in recovery as residue. Thus, the variation of the relative yields of the fatty-acid esters proved to be a good measure to evaluate the degree of PBSA biodegradation. Furthermore, the local structural changes for the biodegraded PBSA film samples were also evaluated from the relative yields of these specific esters observed on the pyrograms for tiny pieces of analyte (ca. 0.1 mg) sampled from local points.