Biodegradable polyester coated mulch paper for controlled release of fertilizer

Abstract

Biobased and biodegradable polymers are a promising solution for agricultural plastics problems, especially for pollution and toxic residue from disposed non-degradable plastic mulch films. Application of biobased and biodegradable mulch films has been hindered by poor mechanical properties and higher cost than conventional plastic mulch film (polyethylene and poly (vinyl chloride)). This work explores the performance of multi-layer fertilizer-infused mulch papers fabricated via blade coating and melt compression molding with biodegradable poly (butylene succinate) (PBS), poly (hexamethylene succinate) (PHS), and their copolyesters. The water absorption, tear propagation properties, enzymatic degradation, and fertilizer release behavior of these multi-layer constructions are characterized. The influence of processing methodology on the coating performance is also discussed. It was found that a polymer concentration of 90 mg/ml in the blade coating process increased the coating thickness to about 30 μm, which slowed water absorption; however, the composition ratio of PBHS polymer coatings had little effect on water absorption. The coatings improved the tear propagation resistance up to 3 N (comparable with that of PE mulch film, 1.6 N) and biodegradation resistance of MP in soil. In this work, PHS coated MP provide an optimal strategy for the dual functions of mulching and fertilizer controlled release, as demonstrated by the barrier properties, degradation rate and mechanical properties. Plant growth trials demonstrated improved fertilizer utilization from slow-release coated papers, as shown by acceleration of the blossom and root growth.