Nanocomposite films are prepared using normal maize starch, plasticized with glycerol and water and three different types of montmorillonite clay employing the solution method. A series of samples with different compositions is prepared by varying the concentrations of glycerol and nanoclay. The tensile properties of films are investigated as a function of clay and plasticizer contents. The experimental results indicate a significant improvement in the mechanical properties of nanocomposite films prepared with sodium montmorillonite clay as compared to commercial organoclay and Kimolian montmorillonite clay. ANOVA tests and regression models indicate that both glycerol and clay contents influence significantly the mechanical properties of films, and the tensile properties of nanocomposite films are enhanced even at lower clay content. The best results are obtained with nanocomposites at glycerol concentration of about 20 wt% and clay content of about 10 wt%. The intercalated nanocomposite structure of the films is ascertained by wide angle XRD analysis whereas the morphology of samples is examined by scanning electron microscopy, optical microscopy, and confocal laser scanning microscopy.
Starch systems containing bioactive compounds (ibuprofen, acetylsalicylic acid, paracetamol, myristic acid) are produced in a pilot plant scale spray dryer. The obtained powders are characterized in terms of their physical properties namely moisture, solubility, bulk and tapped density, suspensibility, hygroscopicity, cohesiveness, flowability, and particle size. The effect of spray drying processing parameters and storage relative humidity on the physical properties of powders is investigated. Light microscopy and Confocal Laser Scanning Microscopy (CLSM) are used to characterize the morphology of the powders and assess possible interaction of amylose with the bioactive compounds. A multiple response optimization is performed to determine the optimal physical properties for achieving the ideal powder formulation that jointly satisfy the spray drying operating conditions. Results revealed that the physical properties of powders are mainly affected by the different operating conditions employed during spray drying. All samples displayed significant differences in their physical properties. Microscopic examination showed the presence of disrupted and intact starch granules, albeit swollen. The optimal processing parameters for the production of spray dried powders with more satisfactory physical properties are obtained at high inlet temperatures. Principal component analysis (PCA) and cluster analysis (CA) showed that there are strong positive correlations among the physical properties of the powders.
Nature has developed several biodegradable materials which can be used in architectural and civil engineering to address the challenges of a more sustainable construction and housing industry to mitigate and adapt to climate change. Nowadays, there is an increasing interest in using biodegradable polymers from renewable resources such as starch and cellulose derivatives in the global plastic industry in order to reduce the environmental pollution caused by the petroleum-based traditional synthetic plastic waste. In this study, conventional composite and nanocomposite films of plasticized corn starch were prepared with sodium montmorillonite clay by a solution mixing procedure with glycerol as a plasticizer. The obtained nanocomposite microstructures were ascertained by XRD and SEM techniques and the tensile properties were investigated as a function of clay and plasticizer contents, in order to analyze the mechanical properties of the films.
Biocomposite films were prepared using normal maize starch plasticized with glycerol and water and sodium montmorillonite clay particles employing the solution mixing procedure. Scanning electron microscopy (SEM), X-ray diffraction (XRD), three-dimensional profilometry and tensile along with nanoindentation tests assisted with a Finite Element Analysis (FEA) were used for the assessment of starch-based films with various percentages of nanoclay particles. XRD analysis revealed intercalation of the test specimens while their morphology was ascertained using SEM/EDX. The FEA results were compared with the experimental measurements from nanoindentation and tensile tests. A satisfactory correlation was obtained between the experimental measurements and the computational models, demonstrating FEA-assisted nanoindentation as a useful technique for assessment, showing the effect of the different nanoclay concentrations on the mechanical properties.
The objective of this research is the fabrication of biodegradable starch-based sandwich materials. The investigated sandwich structures consist of maize starch-based films as skins and biodegradable 3D-printed polylactic filaments (PLA) as the core. To investigate the tensile properties of the skins, conventional and nanocomposite films were prepared by a solution mixing procedure with maize starch and glycerol as the plasticizer, and they were reinforced with sodium montmorillonite clay, cellulose fibers and fiberglass fabric, with different combinations. Test results indicated a significant improvement in the mechanical and morphological properties of composite films prepared with sodium montmorillonite clay in addition with cellulose fibers and fiberglass fabric, with 20 wt% of glycerol. The morphology of the skins was also examined by scanning electron microscopy (SEM). Three orders of hierarchical honeycombs were designed for the 3D-printed core. To investigate how the skin material and the design of the core affect the mechanical properties of the starch-based sandwich, specimens were tested under a three-point bending regime. The test results have shown that the flexural strength of the biodegradable sandwich structure increased with the use of a second order hierarchy core and starch-based skins improved the strength and stiffness of the neat PLA-based honeycomb core. The bending behavior of the hierarchical honeycombs was also assessed with finite element analysis (FEA) in combination with experimental findings. Flexural properties demonstrated that the use of starch-based films and a PLA honeycomb core is a suitable solution for biodegradable sandwich structures.
A review of the recent literature shows that the use of more sustainable, eco-friendly recycled waste materials made from natural biopolymers is an important step of the planning process to reduce the environmental impacts of traditional building materials such as cement and concrete products. This study introduces the application of maize starch in the production of a novel biodegradable construction material. The samples prepared in this investigation were formed by heating a mixture of different proportions of starch, water and sand. The structural properties, morphology and chemical composition of materials were investigated by scanning electron microscopy (SEM) coupled with thermal gravimetric analysis (TGA). The structural characteristics and morphology of the study material to a certain extent resemble natural sandstones, the most common type of sedimentary rocks. Based on the uniaxial compressive strength classification schemes, comparing with the brittle deformation behavior of natural rocks, it can be considered that this material behaves as a polymer - matrix composite with a ductile - thermoplastic mechanical behavior.
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