Evaluation of Starch-Garlic Husk Polymeric Composites through Mechanical, Thermal, and Thermo-Mechanical Tests.

The present work evaluates the influence of different properties of composite materials from natural sources. Films were prepared using the evaporative casting technique from corn starch reinforced with a waste material such as garlic husk (GH), using glycerin as a plasticizer. The results of the syntheses carried out demonstrated the synergy between these materials. In the morphological analysis, the compatibility and adequate dispersion of the reinforcer in the matrix were confirmed. Using Fourier transform infrared spectroscopy (FTIR), the interaction and formation of bonds between the matrix and the reinforcer were confirmed by the presence of some signals such as S-S and C-S. Similarly, thermogravimetric analysis (TGA) revealed that even at low concentrations, GH can slightly increase the decomposition temperature. Finally, from the results of dynamic mechanical analysis (DMA), it was possible to identify that the storage modulus increases significantly, up to 115%, compared to pure starch, especially at low concentrations of the reinforcer.

Evaluation of Thermal Properties of Composites Prepared from Pistachio Shell Particles Treated Chemically and Polypropylene.

The purpose of the present work was to prepare polypropylene (PP) matrix composited filled with chemically treated pistachio shell particles (PTx), and evaluate their effect on the composites' thermal properties. PP-PTx composites were formulated in different PTx content (from 2 to 10 phr) in a mixing chamber, using the melt-mixing process. The PTx were chemically treated using a NaOH solution and infrared spectroscopy (FTIR). According to thermogravimetric analysis (TGA), the treatment of pistachio shell particles resulted in the remotion of lignin and hemicellulose. The thermal stability was evaluated by means of TGA, where the presence of PTx in composites showed a positive effect compared with PP pristine. Thermal properties such as crystallization temperature (Tc), crystallization enthalpy (∆Hc), melting temperature (Tm) and crystallinity were determinate by means differential scanning calorimetry (DSC); these results suggest that the PTx had a nucleation effect on the PP matrix, increasing their crystallinity. Dynamic mechanical analysis (DMA) showed that stiffness of the composites increase compared with that PP pristine, as well as the storage modulus, and the best results were found at a PTx concentration of 4 phr. At higher concentrations, the positive effect decreased; however, they were better than the reference PP.

Isolation of ocotillol/ocotillone from Fouquieria splendens (Ocote) using a batch reactor.

Exploitation of the "ocotillo" tree (Fouquieria splendens Engelm) to produce ocotillol/ocotillone (o/o) in Northern Mexico hasn't been explored to this date. In the present work, isolation of ocotillol/ocotillone was performed through a batch reactor, which allowed the elimination of alcohol and phenols present in the ocote plant, yielding only resins and waxes from the ocote trunks. The ocotillol/ocotillone was extracted from the remaining resin on the ocote logs by solvent extraction in a batch reactor, to be crystallized after its extraction using a rotary evaporator. FTIR, and NMR analysis exhibited the characteristic ginsenoside bands, while the UV-vis spectrum of ocotillol/ocotillone depicted an absorption band belonging to the O-H bonds, indicating that the group is anchored to the ginsenoside structure and not due to a water signal. Lastly, the thermogravimetric analysis described a common behavior among other ginsenosides. Production of ocotillo/ocotillone has an energy consumption of 3624 kWh/gr. With a cost of $0.478 USD in laboratory equipment, which translates as a plausible sustainable production of ocotillol/ocotillone.

Multidimensional Nanocomposites of Epoxy Reinforced with 1D and 2D Carbon Nanostructures for Improve Fracture Resistance.

A hybrid nanocomposites based on epoxy reinforced with a combination of 1D and 2D carbon nanomaterials for improving impact resistance are reported. Multi-walled carbon nanotubes and oxidized-multi-walled carbon nanotubes are used as 1D nanoreinforcements, and graphene derivative materials such as graphene oxide and reduced graphene oxide are utilized as 2D nanoreinforcements. In this research, the impact resistance of epoxy matrix reinforced with 1D or 2D and the mixture of both nanomaterials is studied. The research is focused on evaluation of the influence of adding different combinations of nanomaterials into epoxy resin and their Izod impact response. Moreover, fracture surface of nanocomposites is observed by scanning electron microscopy. Images show differences between the surfaces of brittle nature on thermoset epoxy polymer and tough nanocomposites. Synergy created with 1D and 2D nanomaterials produces stable dispersions in the processing, reflected in the interface. The interactions in nanocomposites are evidenced by infrared spectra, principally on the peaks related to oxygenated functional groups present in nanomaterials and absent in polymer matrix. Consequently, an increase of 138% in fracture strength of nanocomposites is exhibited, in comparison to the neat epoxy matrix. In addition, hybrid nanocomposites were synthesized in two different methods to evaluate the influence of manufacturing method on final properties of nanocomposites.

Chitosan/Mimosa tenuiflora films as potential cellular patch for skin regeneration.

Bio-composites films were prepared by casting and drying of aqueous solutions containing different weight ratios of chitosan and bark of Mimosa tenuiflora. The physico-chemical and functional properties of the films were characterized by scanning electron microscopy, dynamical mechanical analysis, wettability, cytotoxicity and in vitro antibacterial activities. The morphology studies confirmed that the presence of Mimosa tenuiflora change the surface of films. Moreover, the incorporation of Mimosa tenuiflora improved the thermal stability of the films, as it was indicated by the changes in the glass temperatures obtained. Water-uptake ability changed in relation to polymeric composition of film. This property increased by the addition of Mimosa tenuiflora to the film. Improved antibacterial properties were measured against Escherichia Coli and Micrococcus lysodeikticus or luteus. Finally, cytotoxicity was studied by MTT assay and the films were non-toxic. These preliminary results provide a cheap way to prepare chitosan/Mimosa tenuiflora films for wound healing and skin regeneration.

Effects on the Thermo-Mechanical and Crystallinity Properties of Nylon 6,6 Electrospun Fibres Reinforced with One Dimensional (1D) and Two Dimensional (2D) Carbon.

Electrospun one dimensional (1D) and two dimensional (2D) carbon based polymer nanocomposites are studied in order to determine the effect provided by the two differently structured nanofillers on crystallinity and thermo-mechanical properties of the nanofibres. The nanomaterials studied are pristine carbon nanotubes, oxidised carbon nanotubes, reduced graphene oxide and graphene oxide. Functional groups associated with the order structure of the polymers are analysed by infrared and Raman spectroscopies; the morphology is studied by scanning electron microscopy and the crystallinity properties are investigated by differential scanning calorimetry and X-ray diffraction. Differences in crystallisation behaviour between 1D and 2D carbon based nanofibres are shown by their crystallinity degree and their crystal sizes. The nanocomposite crystal sizes perpendicular to the plane (100) decrease with nanofiller content in all cases. The crystallinity trend and crystal sizes are in accordance with storage modulus response. The results also suggest that functionalisation favours interfacial bonding and dispersion of the nanomaterials within the polymer matrix. As a consequence the number of nucleating sites increases which in turn decreases the crystal size in the nanocomposites. These features explain the improved thermo-mechanical properties in the nanocomposites.