ABSTRACT
The increasing use of petroleum plastics has caused environmental damage due to the degradation time of these materials. An alternative to petroleum plastics could be thermoplastic starch (TPS). However, thermoplastic starch does not exhibit satisfactory tensile properties. The mechanical properties of thermoplastic starch can be improved by adding sisal microfibers. Thus, the objective of this study was to evaluate the influence of different levels of glycerol and sisal microfibers on the thermal and tensile properties of thermoplastic corn starch composites. The microfibers were obtained via mechanical treatment followed by chemical treatment (alkaline treatment and bleaching). The films were obtained by the casting method using commercial corn starch and glycerol as a plasticizing agent, reinforced with sisal microfibers. Fourier transform infrared spectroscopy (FTIR) results revealed that the addition of microfibers did not change the chemical structure of the TPS matrix. The films from the samples with 18% glycerol and 10% microfibers had the highest value for the maximum tension, equal to 4.78 MPa. The thermal decomposition profile of TPS was not altered by the addition of microfibers. Our findings demonstrated the profound influence of glycerol and microfiber contents on the tensile properties of thermoplastic starch composites.
ABSTRACT
Chitosan comprises polymeric macromolecules with technical and biological properties that have been used in biomedical healing applications requiring anti-microbial and anti-inflammatory capacities worldwide. In the tropical regions, green banana peel extract and andiroba oil are considered natural products with wound healing properties. The present study, for the first time, synthesized chitosan/green banana peel extract/andiroba oil (CGA) membranes and analyzed them using scanning electron microscopy (SEM) and the swelling and moisture tests. The CGA membranes together with control membranes of plain chitosan and chitosan plus green banana peel extract, were characterized by contact angle measurement, X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Macroscopic analysis showed significant differences in color and transparency caused by the number of decoction days used for extract preparation and the oil content. SEM observations disclosed the formation of two phases, lipid and polymer, in the CGA. The number of decoction days and the andiroba oil content were inversely related to the swelling moisture uptake. All membranes were found to be hydrophilic with contact angles less than 90°. The incorporation of plant extract and oil promoted the appearance of related XRD peaks. DSC curves revealed a reduction in the enthalpy of the CGA membranes compared with plain chitosan, which might be attributed to the evaporation of the natural extract and oil. Based on these findings, the studied newly synthesized membranes demonstrated a potential for healing epithelial lesions.
