Biodegradable and Biobased Mulch Films: Highly Stretchable PLA Composites with Different Industrial Vegetable Waste

Highly stretchable biobased and biodegradable agricultural mulch films based on polylactic acid (PLA) and 10, 20, or 30 wt % various nonedible vegetable wastes such as spinach stems (SS), tomato pomace (TP), and cocoa shells (CS) are prepared and characterized in this work. The results demonstrate that appropriate PLA plasticization and vegetable waste addition allow for obtaining films suitable for mulching with tensile strengths in the 10-24 MPa range and elongations at break up to 460%, depending on the kind and amount of vegetable waste incorporated. Additionally, the developed mulches show low water solubility (1-15 wt %) and moisture content (1-3 wt %) with a water vapor permeability of up to 3 × 10^-10 g s^-1 m^-1 Pa^-1, similar to that of Mater-Bi. In addition, the type of vegetable waste added as filler were demonstrated to significantly affect not only the films' mentioned properties but also their biodegradability. For instance, films prepared with 20 wt % SS were demonstrated to improve PLA soil biodegradability, which increased from 0 to 38 wt % for PLA composites after 6 months of a soil burial experiment. Lastly, the developed composites contain different amounts of plant micro- and macronutrients, indicating their potential as fertilizers. The results found in this work represent a sustainable, fully biobased alternative to other mulches already in the market.