Utilization of ramon seeds (Brosimum alicastrum swarts) as a new source material for thermoplastic starch production

The development and characterization of biodegradable polymers deriving from renewable natural sources has attracted much attention. The aim of this work was to partially characterize a thermoplastic starch obtained from the starch of seeds from the ramon tree (TPS‐RS) as an option to substitute thermoplastic starch from corn (TPS‐CS), in some of its applications. At 55% of relative humidity (RH), TPS‐RS had higher tensile strength and deformation than TPS‐CS. X‐ray diffraction analysis showed similar values in residual crystallinity (percentage of crystallinity that remains after plasticization process) in both TPS. The SEM micrographs showed a few remnant granular structures in the TPS‐RS. The FTIR showed a greater intensity in band at 1016 cm^?1 in the TPS‐CS and TPS‐RS in comparison with their corresponding native starch, indicating an increase in the amorphous region after plasticization. The TGA analysis showed greater thermal stability in TPS‐CS (340 °C) compared with TPS‐RS (327 °C). In addition, the glass transition temperature in both TPS was 24 °C. The results obtained represent a starting point to potentialize the use of TPS‐RS instead of TPS‐CS for the development of new biodegradable materials for practical applications in different areas. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44235.     

Struma cordis: first case in Mexico

The Intracardiac ectopic thyroid is an extremely rare condition and there is no previous report on this subject in Mexico. This is the case of a 33 years old woman, with normal thyroid function. She was found to have an intracardiac tumor in the interventricular septum. The intraoperative biopsy showed typical thyroid follicules; tumor removal left a septal defect that was closed with a dacron patch suture. Two years follow-up showed normal echocardiographic images, good clinical status an normal thyroid functioning. A brief review of the literature is included.     

Alumina-silica binary mixed oxide used as support of catalysts for hydrotreating of Maya heavy crude

Alumina-silica binary mixed oxide support is used to prepare catalysts for hydrotreating of Maya heavy crude. Support is prepared by urea hydrolysis. Sequential incipient wetness and co-impregnation techniques are employed for preparation of catalysts. Ammonium heptamolybdenum is used as precursor of MoO₃. Catalysts are characterized by X-ray diffraction (XRD), temperature-programmed reduction (TPR) and the pore size distribution. Hydrodemetallation (HDM), hydrodesulfurization (HDS), hydrodenitrogenation (HDN), and asphaltene conversion (HDAsp) reactions are studied on these catalysts. One reference catalyst is also taken for comparison. Coke and metals depositions on spent catalysts are measured. The catalyst deactivation rate is also studied. The X-ray diffraction (XRD) results reveal that molybdenum atoms are well dispersed into CoMo catalyst, whereas MoO₃ crystalline phases are found in PCoMo and PNiMo catalysts. TPR reduction profiles are different for different catalysts. The laboratory made catalyst is reduced at one temperature, whereas the reference catalyst shows two reduction profiles. The reference catalyst shows the highest activities among four catalysts. The highest HDM and HDAsp activities of the reference catalyst may be due to its bigger pore diameter. The presence of TiO₂ in the reference catalyst enhances HDS and HDN activities. The CoMo catalyst shows higher activities than those of PCoMo and PNiMo catalysts. The presence of crystalline MoO₃ causes for lower activities of catalysts PCoMo and PNiMo.     

Biocomposites based on poly(lactic acid) and seaweed wastes from agar extraction: Evaluation of physicochemical properties

Seaweed waste (SWW) is a residue or by‐product from the filtration step of the agar extraction process, and it has been explored as an inexpensive and effective filler for incorporation by melt blending into a poly(lactic acid) (PLA) matrix. PLA‐SWW biocomposites were manufactured with various contents of SWW (0, 5, 10, 15, and 20 wt %) using a sheet extrusion process. PLA was functionalized with maleic anhydride (MAH) by reactive extrusion using dicumyl peroxide (DCP) as an initiator, and it was extruded using 0, 5, and 20 wt %. SWW content. The mechanical, thermal, structural, and morphological properties of the processed biocomposites were investigated. Regarding the mechanical behavior, a slight increase in the tensile modulus was observed at low SWW content. The thermal properties indicated that the rigid amorphous phase content was enhanced in the biocomposites. This work suggests that SWW can be used as filler to develop environmental friendly biocomposites. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42320.     

Preparation and characterization of low density polyethylene‐agar biocomposites: Torque‐rheological,mechanical, thermal and morphological properties

Low density polyethylene (LDPE) and agar were blended by using the former as an internal mixer and varying the amount of agar. Resulting blends were hot pressed and characterized with regard to their torque‐rheological, mechanical, dynamic‐mechanical, thermal, and morphological properties. The torque rheological properties were determined using classical power law model. Tensile properties of LDPE‐agar biocomposites showed that agar improves the tensile modulus (stiffness), but compromise the tensile strength and elongation at break. Viscoelastic behavior of the matrix is clearly influenced by the presence of agar biofiller as shown by the dynamic mechanical analysis (DMA). Thermal behavior of the biocomposites was also investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Morphological observations by scanning electron microscopy (SEM) show the ductile to brittle fracture of LDPE‐agar biocomposites subjected to tensile test. This work is an initial reference to identify potential applications of biocomposites based‐on agar as a biofiller. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers     

Evaluation of rheological properties of non-newtonian fluids in internal mixers: An alternative method based on the power law model

A new method was developed to evaluate rheological properties of polymer melts such as shear stress, shear rate, apparent viscosity and other rheological parameters in internal mixers. It is based on the classical power law model where the power law index n is directly evaluated from a set of data containing speed S, torque M, and the consistency index m is indirectly determined by an empirical relation. The method is based on a model with only one geometrical parameter (α), which involves a chamber radius R₂ and an equivalent radius R_e. It is assumed that the measuring head consists of two adjacent sets of coaxial cylinders. This method has advantages over previously reported models that use two parameters and do not propose a straightforward method to evaluate m. The pseudoplastic nature of the polymer melt decreases as the rate of loss of structural points, i.e., molecular entanglements and network junctions, increases, which produces greater mobility of the melt. A relationship between α and C(n) is found, which is simpler than other models previously reported. These results further demonstrate the feasibility of evaluating rheological properties of polymer melts in internal mixers.     

A review on the technical adaptations for internal combustion engines to operate with gas/hydrogen mixtures

The use of the hydrogen as fuel in the internal combustion engine represents an alternative use to replace the hydrocarbons fuels, which produce during the combustion reaction a pollutes gases. The hydrogen is the most abundant material in the universe and during its combustion with air only produces nitrous oxides (NO_x) gas, which can collect and avoid their emission to the atmosphere. In this paper we can present the most significant advances and developments made on the technical adaptations in the internal combustion engines which operate with mixtures of gas/hydrogen, doing more emphasis in the fuel injection and cooling systems. To understand such technical adaptations, it is necessary to know the chemical and physical characteristics of the hydrogen, and the processes relate with the chemical reaction between air and hydrogen, from a point of view of the thermo-chemistry and the chemical kinetics, as well as the ratios of the mixtures in the combustion process. Also, it mentions the advantages and disadvantages of the integration of hydrogen as a fuel, such as the pre-ignition, spontaneous ignition, knocking and backfire, also the advances in the research to avoid these phenomena during the combustion. Finally, it describes the best conditions of the ratio-mixtures in the internal combustion engines when they are fed with hydrogen. Also, it describes the perspectives and the futures fields on the future investigation.     

Microstructure formation in polymer composites prepared with polypropylene and a polyaniline complex

BACKGROUND: Results of a feasibility study to produce elongated structures of an electro‐conductive polyaniline complex (PANICOM) within polymer composites by means of an in situ deformation process are reported. The aim was to find an alternative route to produce fiber‐like polymer materials with potential applications in electrostatic discharge (ESD) protection. PANICOM–polypropylene blends with PANICOM contents ranging from 1 to 50 wt% were capillary extruded. The microstructure was analyzed using optical and scanning electron microscopy. Conductivity measurements were carried out. Tensile mechanical properties were also characterized. RESULTS: PANICOM was deformed into elongated structures, embedded within the polypropylene, preferentially oriented in the extrusion direction. The highest conductivity levels were reached for PANICOM contents of 15 wt% and greater. For contents of PANICOM of about 5 to 10 wt%, the conductivities lay within the optimal ESD range, and the breaking tenacity was only about 25% lower than that of pure polypropylene. CONCLUSION: The results obtained provide further evidence to support the feasibility of producing electrically conductive fibers of PANICOM within a suitable polymer matrix by means of a simple in situ deformation process, so as to allow the fabrication of conducting composites with potential applications in ESD protection. Copyright © 2009 Society of Chemical Industry     

Synthesis of carbon nanostructures from residual solids waste tires

This article presents the results of the synthesis and morphological characterization of carbon nanostructures obtained from the decomposition of residual solid from waste tires (RSWT) in quartz tubes under reduced pressure (1.33 Pa) at 900°C for 15 min. The synthesis led to the formation of two phases, a fragmented solid black powder composed of multi‐walled carbon nanotubes (MWCNTs), onion‐type fullerenes, and spheres, and a very bright metallic dark film. Analysis by microscopy (SEM and TEM) showed that the MWCNTs had an average diameter of approximately 25 nm and a length greater than 100 nm while the diameter of the onion‐type fullerenes was found to be 8 nm. The nanospheres showed different diameters ranging from 500 nm to 1.5 μm, and some had a metallic core surrounded by layers of carbon. The infrared spectra of the nanotubes exhibited absorption bands at 1558 and 1458 cm^?1, corresponding to C?C and C? C bonds, and signals at 3438 and 1080 cm^?1 related to the OH and C? O groups from oxidized graphite as it was identified in the dark film. The Raman spectra of the carbon nanostructures present D and G‐bands at 1331 and 1597 cm^?1, respectively. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Damage development in a noncrimp‐glass fabric reinforced epoxy composite material

The relationship between textile architecture and the damage sequence under tensile loading has been investigated experimentally for a composite material reinforced with a noncrimp glass‐fiber textile of configuration [0°, +45°, 90°, −45°] stacking sequence based on epoxy resin matrix cured with high‐temperature hardener. The system chosen for this work consists of a bifunctional epoxy, diglycidyl ether of bisphenol A, cured with a tetrafunctional amine, diaminodiphenyl sulfone (DDS). This system ensures to obtain a rigid material with excellent mechanical properties in order to observe, analyze, and identify the process and progress of the generated damage and the failure mechanism which leads to the materials fracture. The properties have been studied for each ply direction at 0°, +45°, 90°, and −45° in order to make a comparative assessment of the influence of the polyester (PES) yarns in zig‐zag and unidirectional geometry, that hold together the four plies in the textile, in the composite damage generation. The laminates were uniaxially tensile loaded until final fracture occurred. It was found that PES threads have an effect on cracking progression depending on the textile orientation. POLYM. COMPOS., 2009. © 2009 Society of Plastics Engineers