Scale-up fabrication of a biodegradable PBAT/PLA composite film compatibilized with a chain extender for industrial agricultural mulch film application

Low-density polyethylene (LDPE) mulch films have become a prevalent practice in agriculture to increase crop yield. However, because of their high environmental impact after use, biodegradable plastic films are considered desirable alternatives in agroecosystems. Herein, a polybutylene adipate-co-terephthalate (PBAT) and polylactic acid (PLA) composite film compatibilized with a chain extender (CE) was prepared via a two-step extrusion process. First, PBAT and PLA were blended at different ratios in a laboratory-scale twin-screw extruder, and the PBAT/PLA blends (80/20 wt.%) compatibilized with 1 phr of CE exhibited the most comparable physicochemical properties. The CE integration into the PBAT/PLA binary blend significantly increased mechanical rigidity and strength (p ≤ 0.05). The enhanced compatibility between the immiscible polymers was verified through thermal and phase morphological analyses. The optimum composite was then produced using a pilot-scale extrusion system. The pilot-scale extruded optimal biodegradable mulch composite exhibited excellent water barrier properties, as evidenced by a water vapor permeability of 0.83 g·mm/m2·day·kPa and a water contact angle of 93.77°. These values surpassed those of commercially available biodegradable mulch films. Furthermore, it demonstrated a weight reduction of 2.9% during a 3-month period of soil burial, exhibiting durability compared to commercial biodegradable mulch films. These results suggest that the developed film has great potential for practical food and agricultural applications.