Dry fibers coming from garden waste, originating from Opuntia ficus indica, were introduced in amounts of either 8 or 16 wt % into a self-produced thermoplastic starch (TPS) based on potato starch and glycerol. Thermal (differential scanning calorimetry, DSC), mechanical (tensile tests), and morphological characterization with scanning electron microscopy (SEM) and performing energy-dispersive X-ray spectrometry (microanalysis) were carried out. The results indicated that the uneven distribution and variable geometry of fibers introduced led to a reduction of tensile stress and strain with respect to pure TPS. However, the positive effects of prolonged mixing and increased thickness were highlighted, which suggest the fabrication of the composite could be improved in the future by controlling the manufacturing procedure.
Opuntia cladodes are a typical vegetable waste, from which mucilage in gel form can be extracted. This work proposes blending it with a self-produced thermoplastic starch (TPS), originating from potato starch with a high content in glycerol (ca. 30%). Three methods were compared for extraction, bare maceration (MA), mechanical blending (ME) and mechanical blending following maceration (MPM) to produce films with an approximate thickness of 150 μm. For the comparison, tensile testing, differential scanning calorimetry and scanning electron microscopy were used. The MPM process proved the most effective, not only for extraction yielding, but also to obtain a larger deformation of the samples with respect to the one allowed by the pure TPS films. A considerable plasticization effect was observed. Despite this, the mechanical performance is still not completely satisfactory, and the expected effect of the calcium and magnesium salts contained in the mucilage to improve the rigidity of the TPS film was not really revealed. Prospected improvements would concern the fabrication process and the investigation of other possible loading modes and sample geometries.
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