Biodegradation behavior of PHAs with different chemical structures under controlled composting conditions

Polyhydroxyalkanotes (PHAs) are biobased and biodegradable polymers, of which poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV, 3 %mol HV) and poly-3-hydroxybutyrate-co-4-hydroxybutyrate [P(3HB,4HB), 10 %mol 4HB] are currently commercialized. To understand the influence of chemical structure on the biodegradability of PHA, the biodegradation behavior of poly(hydroxybutyrate) (PHB), PHBV (40 %mol HV), PHBV (20 %mol HV), PHBV (3 %mol HV) and P(3HB,4HB) (10 %mol 4HB) were investigated under the controlled composting conditions according to ISO 14855-1. It was found that PHAs with different chemical structures can be biodegraded under the controlled composting conditions. The order of biodegradability was P(3HB, 4HB) (40 %mol 4HB) ≈ PHBV(40 %mol HV) >PHBV(20 %mol HV) >PHBV(3 %mol HV) >PHB.