Materials Literature
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La eficiencia de estabilizantes termicos a base de metales Ca-Zn pueden incrementarse mas del 50% cuando se les anade hidrotalcita. En este trabajo se comparan resultados de estabilidad termica -medida con dos metodos: estatico (por conductividad) y dinamico (con un reometro de torque)- para determinar diferencias en…
La poli(e-caprolactona) (PCL) fue preparada a partir de la polimerizacion por apertura de anillo (ROP) iniciada con acetato de samario (III) (SmAc3). Se investigo el efecto de la relacion molar monomero/iniciador (M/I) y el tiempo de reaccion sobre la conversion y el peso molecular del polimero. Los materiales obtenid…
En este trabajo se estudió la influencia de las variables del proceso de inyección, sobre la respuesta en impacto biaxial de piezas de Polipropileno homopolímero (PPH). Con este fin, se fabricaron probetas con geometría de disco variando sistemáticamente las temperaturas de molde (Tm) y de inyección (Ti). Como resulta…
Se prepararon una serie de poliesteruretanos (PEUs) basado en polilactida mediante un proceso de reaccion catalizada en dos etapas. Los PEUs se caracterizaron por DSC y microscopia optica de luz polarizada. Estos tuvieron mayor temperatura de cristalizacion en frio, cinetica de cristalizacion mas lenta y los puntos de…
El presente trabajo tiene por objetivo sintetizar nanocompuestos mediante polimerizacion in situ de etileno usando Cp 2 ZrCl 2 /MAO como sistema catalitico con hidroxiapatita (HA) y nanotubos de carbono de pared multiple funcionalizados (NTCPMf) recubiertos con HA. Se emplearon nanoparticulas de HA tipo agujas sinteti…
A partir de la tecnica electrospinning, se obtuvieron estructuras tridimensionales biodegradable tipo andamio empleando para esto una solucion de poli(acido lactico) (PLA) en cloroformo. Para estudiar el efecto de los parametros del proceso en cuanto al diametro y morfologia de las fibras se vario: concentracion de la…
New ferrielectric 0.9Ag0.9Li0.1NbO3–0.1Bi0.5K0.5TiO3 ceramics have been obtained. At room temperature ceramics exhibit perovskite structure, which is close to rombohedral-tetragonal phase boundary. The dielectric properties of ceramics were investigated in wide frequency range from 20 Hz to 1 GHz at temperatures 200 K…
Se estudio el efecto de la adicion de 5% de una nanosilice (NS) hidrofobica sobre la cristalizacion y propiedades tensiles del PP y de mezclas ricas de este (80%) con poliamida 6 (PA6) o con policarbonato (PC). Al evaluar la morfologia de fases de las mezclas por microscopia electronica se verifico el efecto “emulsifi…
Se prepararon mezclas de poliestireno (PS) y polibutadieno (PB) con arcillas modificadas comercialmente, empleando estireno (St) como solvente. Se investigo la influencia de algunos factores termodinamicos y cineticos, tales como: el tipo de modificador organico de la arcilla, el orden de adicion de los componentes y…
We briefly review the distinction between abstract groups and symmetry groups of objects, and discuss the question of which groups have appeared as the symmetry groups of physical objects. To our knowledge, the quaternion group (a beautiful group with eight elements) has not appeared in this fashion. We describe the q…
The objective of this project is to determine the diffusivity and chemical behavior of key fission products (ag, Cs, I. Te, Eu and Sr) through SiC and PyC both thermally, under irradiation, and under stress using FP introduction techniques that avoid the pitfalls of past experiments. The experimental approach is to cr…
In this study, a low-temperature hydrothermal method is used to synthesize crystalline zinc oxide powders with various morphologies on glass, silicon and indium tin oxide substrates. The study found that each respective substrate produced a variation in the morphology of the zinc oxides produced at the reaction temper…
Ba0.98Bi0.02(Ti0.9Zr0.1)1−xCuxO3 (x = 0, 0.01, 0.02, 0.03 mol) ceramics were prepared by a solid state processing. X-ray diffraction analysis indicates that all of the ceramics samples have tetragonal crystal structure. The dielectric constants as a function of temperature at different frequencies show that all of the…
In this study, a low-temperature hydrothermal method is used to synthesize crystalline zinc oxide powders with various morphologies on glass, silicon and indium tin oxide substrates. The study found that each respective substrate produced a variation in the morphology of the zinc oxides produced at the reaction temper…
In the present study, high-sensitivity photodetection has been demonstrated using an amorphous selenium (a-Se) based photodetector driven by nitrogen-doped diamond cold cathode. The emission current – applied voltage characteristics are compared between different lighting conditions, and their sensitivities are evalua…
This paper reports a finite element study of effect of bonding strength between metal and ceramic. The bonding strength is evaluated with different processing temperature and holding time. The difference between the coefficients of linear thermal expansion (CTEs) of the metal and ceramic induces thermal stress at the…
Hysteretic loop measurements of hydrostatic piezoelectric coefficient as a function of temperature and pressure for the lead-free ferroelectric ceramic 0.79(Bi0.5Na0.5)TiO3 – 0.14(Bi0.5K0.5)TiO3 – 0.07BaTiO3 (BNBK79), were realized. Curves of dh – E relation were obtained under applied electric field along polar axis…
The effects of substituting Na+ for Bi3+ on the sintering properties, the microstructure and the dielectric properties of Bi2(Zn1/3Nb2/3)2O7 -based ceramics were investigated. The results reveal that the sintering temperature of (Bi2−xNax)(Zn1/3Nb2/3)2O7 (x = 0.1, 0.2, 0.25, 0.3, 0.35, 0.4, 0.5 and 0.6 mol) ceramics d…
The reaction of the complexes trans-[RuII(NO+)(NH3)4L] and [RuII(NO+)HEDTA] with 2,2-diphenyl-1-picrylhydrazyl (DPPH•) and hydroxyl (OH•) radicals has been investigated at 25.0 ± 0.1 °C using spectroscopic (UV-vis and electron paramagnetic resonance) and electrochemical techniques (differential pulse voltammetry and c…
The dispersion analysis of the dielectric spectra of the perovskite ceramics, CaTiO3, and perovskite-like monocrystalline thin films (Ba,Sr)TiO3 deposited on a monocrystalline MgO substrate is carried out. The giant LO–TO splitting (∼700 cm−1) of the lowest-frequency absorption band (the soft mode) is found. Due to th…