Dependence of biodegradability of plastics in compost on the shape of specimens

Biodegradation of plastics was tested in compost made with animal fodder. Specimens in film shape as well as in powder shape were subjected to the biodegradation tests to investigate dependence of the test results on the shape of the specimens. Polypropylene (PP) was chosen as a non-degradable plastic. Poly(l-lactic acid) (PLLA) and poly(butylene succinate) (PBS) were selected as slowly degrading plastics while polycaprolactone (PCL) and poly(butylene succinate-co-adipate) (PBSA) were chosen as easily degradable plastics. Biodegradability of PP in film shape as well as in powder shape was tested to investigate the possible change in the microbial aspiration activity, because the shape of the specimens may affect aeration behaviour in the compost. Biodegradation results of PLLA and PBS depended on their shape all through the biodegradation test. In contrast, the shape of PCL and PBSA exerted influences on their biodegradability only at the early stage of the biodegradation, while at the late stage, the biodegradation proceeded almost independently of their shape.