Biodegradation behavior of P(3HB,4HB)/PLA blends in real soil environments

Both poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [P(3HB,4HB)] and poly(lactic acid) (PLA) are biobased polymers, and their blends can be used to prepare biodegradable polymeric materials with good comprehensive properties. In this paper, the biodegradation behavior of P(3HB,4HB)/PLA blends in real soil environments was for the first time investigated via appearance analysis, SEM, FTIR and elemental analysis of their degraded residues. It was found that P(3HB,4HB) and P(3HB,4HB)/PLA blends can be biodegraded under real soil conditions. The order of biodegradability is as follows: PHA-100 [P(3HB,4HB)] > PHA-75 [P(3HB,4HB)/PLA, 75/25] > PHA-50 [P(3HB,4HB)/PLA, 50/50] > PHA-25 [P(3HB,4HB)/PLA, 25/75] > PLA, which correlates well with the PLA content. Due to the different degradation mechanisms, P(3HB,4HB) and PLA have the fastest degradation rate in 20 and 40 cm soil depth, respectively. Their blends also have different degradation rates in different depths of soil.