Physicochemical changes of plastic mulches during biodegradation

What is it about?

The study focused upon the changes in different physicochemical properties of plastic mulches prepared from biopolymers: polylactic acid (PLA) and a blend of PLA and polyhydroxyaltanoate during biodegradation of the plastics in soil. Plastic mulches are an inherent component of the production of many fruits and vegetables, to prevent weeds and reduce evaporative loss of water. This investigation provided a deeper insight into the underlying events and stages of biodegradation, and guidance as to which properties should be monitored during the time course of biodegradation.

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Why is it important?

Our study showed that there are several stages to biodegradation of plastics in soil. During the first stage, soil micoroorganisms "open up" the structure of the plastic, to allow its use as a carbon source, observable through a major loss pf tensile strength. Second, microorganisms selectively utilize preferable components of the plastics as carbon sources, such as polyhydroxyalkanoates (PHA; from a PHA/polylactic acid blend), and regions of lower crystallinity. Subsequently, the biopolymeric components underwent a slow and steady degradation, i.e., a slow and linear decrease of molecular weight with time.

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