Efeito do óleo de coco e da nanoargila no processamento e nas propriedades de amido termoplástico

Abstract

This work aimed to evaluate the effect of processing conditions, incorporation of coconut oil (OC) and organophilic montmorillonite clay (OMMT) on the physical, chemical and mechanical properties of thermoplastic starch (TPS) based on cassava. The use of starch as a source to obtain a thermoplastic material has advantages such as being abundant in nature, biodegradable, low cost, being able to be from different sources and being processed by conventional polymer processing techniques. However, its high susceptibility to moisture and its low mechanical properties are limiting points for its use in several applications. The development of polymeric nanocomposites with vegetable oil additives has been shown to be an excellent alternative for obtaining starch-based materials with better properties. The materials were mixed in a twin-screw extruder and then processed in a single-screw extruder with a flat ribbon die. At blends of TPS, OC and OMMT produced easily processable materials with a good visual appearance. The results of the melt flow index (MFI) measurements showed that the OC and the OMMT promoted a reduction in the fluidity of the materials. Colorimetric analysis showed a change in the color of materials with varying concentrations of OC and OMMT. The X-ray diffraction results indicated the occurrence of clay exfoliation and the formation of polymeric TPS nanocomposites. The water absorption test showed that the simultaneous addition of OC and OMMT in TPS reduced the hydrophilic character of polymeric nanocomposites. Fourier transform infrared spectroscopy (FTIR) results showed the characteristic bands of the TPS, OC and OMMT structures. The mechanical behavior under tensile and Shore D hardness showed an indication of improvement in these properties with the addition of OC and OMMT. The results of the biodegradation test showed that the OC reduced the biodegradability process, while OMMT accelerated the process. The polymeric nanocomposites obtained with TPS/OMMT and OC indicated the potential for applications of new ecologically correct products developed on a large scale.