Effect Of Morphology And Molecular Orientation On Environmental Water Biodegradability Of Poly[(R)-3-Hydroxybutyrate-Co-(R)-3-Hydroxyvalerate]

The biodegradation behaviors of several forms of poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyvalerate] (P(3HB-co-3HV)) in seawater and freshwater, namely, powder, cast film, undrawn fiber, and fivefold-drawn fiber, were analyzed via biochemical oxygen demand, weight loss, and scanning electron microscopy measurements. The powder showed the highest degradation rate, attributed to its larger surface area, which allows microorganisms to attach to the surface and form a biofilm that begins to degrade sooner. The fivefold-drawn fibers degraded more slowly than the undrawn fibers owing to the higher crystallinity caused by the orientation of the former. Moreover, the degradation results of the fivefold-drawn fibers in seawater and freshwater showed that the degradation rate depended on the number of microorganisms in both environmental water types. The analysis of the degradation behavior in the fresh-water revealed that the crystalline and amorphous phases in the film degraded simultaneously, whereas the degradation of the fibers started from the amorphous phase, followed by the crystalline phase. (C) 2021 Elsevier Ltd. All rights reserved.