Development of a Biodegradable Ternary Blend of Poly(vinyl alcohol) and Polyhydroxybutyrate Functionalized with Triacetin for Agricultural Mulch Applications

The development of biodegradable mulch for agricultural applications represents a sustainable approach to reducing plastic pollution. Poly(vinyl alcohol) (PVA) is one of the nontoxic and biodegradable polymers that can be used as mulching film. However, a major drawback of PVA is its moisture sensitivity, which limits its applications. In this study, a biocomposite based on PVA and polyhydroxybutyrate (PHB), plasticized with triacetin, was developed by solvent casting method. The biocomposite film exhibited good mechanical properties, better integrity, reduced transmittance, and light-blocking properties, which can prevent weed growth. Additionally, an improvement in surface characteristics was observed, as demonstrated by the shift in contact angle from 44 to 99° and a reduction in the water vapor transmission rate (WVTR) from 4.82 to 2.31 g/h m2. For agronomic application, the developed films were experimentally applied as mulch for maize plants in pots. The results were positive, showing that the mulches effectively supported the growth of the maize plants. Further, signs of initial degradation were observed after 5 days, and the film reached a degradation level of 50–55% after 30 days under natural conditions. Thus, this work has provided new insights for expanding the application range of PVA films in biobased mulching materials.