Biodegradable Mulch Films Based on Starch/Poly (Lactic Acid)/Poly (ε-Caprolactone) Ternary Blends

Novel formulations based on corn starch (CS), thermoplastic starch (TPS), poly (lactic acid) (PLA) and poly (epsilon-caprolactone) (PCL) were developed in order to evaluate their performance as agricultural mulch films. Neat PLA and PCL samples, binary and ternary films were prepared using a Brabender type mixer. In order to determine the impact of the PCL on final micro- and macroscopic properties of PLA/CS and PLA/TPS formulations with different PCL contents added. The structural, morphological, thermal, rheological, mechanical properties, biodegradation tests, as well as water interaction properties were studied. The obtained results indicated that the introduction of PCL into the PLA/CS and PLA/TPS binary blends caused slight changes. As promising results, bioassays indicated that the growth of tomato plants was positively affected by using these blends based on PLA/CS and PLA/TPS as biodegradable mulch films (BDMs); even, the results were similar as low-density polyethylene (LDPE) particularly: temperature and water retention tomato and weed fresh weights, and chlorophyll content. LDPE is the most generally used material as agricultural mulch films and the mentioned parameters were superior to uncovered tray as control.