Effect of starch initial moisture on thermoplastic starch film properties and its performance as agricultural mulch film

Abstract

In order to evaluate the influence of corn starch (CS) storage in controlled-chambers at different relative humidities on thermoplastic starch (TPS) film properties, CS films were prepared by extrusion using glycerol and water as plasticizers. Four TPS formulations were compared with low-density polyethylene (LDPE) film, which is the most commonly used material as agricultural mulch films. The structural, morphological, thermal, rheological, mechanical properties, biodegradation tests, as well as water (H2O) interaction properties were carried out in this study. Finally, the agricultural mulch film performance, effect of tomato germination and weed suppression were performed by selecting one TPS formulation and was compared with LDPE film and uncovered tray as control. The effect of CS initial moisture modifies the H2O content on TPS film and, consequently, acts as a plasticizer together with glycerol. The increase of plasticizer content produced the modification on macroscopic parameters, especially on H2O interaction properties. However, the obtained results suggested that micro- and macroscopic TPS film properties were not good enough in comparison with LDPE film, particularly for barrier properties. In addition, bioassay indicates that tomato germination was negatively affected by using TPS as mulch film.