SEM Micrographs Of Composites Research Articles

Effect of silane-modification of diatomite on its composites with thermoplastic polyurethane

Diatomite (KG) surface was modified by four different silane coupling agents having amino, epoxy, triamine and octyl functional groups for enhancement of interfacial adhesion between thermoplastic polyurethane (TPU) and diatomite. EDX and FTIR spectroscopy techniques were used to evaluate the surface functionalities of modified and neat KG samples. TPU/KG composites were fabricated using melt-compounding process. Mechanical, thermo-mechanical, thermal, melt-flow and morphological properties of composites were reported. Mechanical tests revealed that tensile strength and hardness of TPU extended to higher levels while its flexibility was retained after KG additions. Epoxy-silane modified KG exhibited the highest results in the case of mechanical properties. Glass transition temperature of TPU shifted to higher values by the additions of modified KG. Thermal stability of TPU raised by KG inclusions regardless of modification type. Modified KG containing composites yield lower MFI values with respect to neat KG. Enhancement of interfacial adhesion between TPU and KG phases was confirmed by SEM micrographs of composites in which silane-modified KG surfaces were covered by TPU matrix. Silane modifiers involving amine and epoxy groups led to significant improvement in properties of KG-filled TPU composites. Epoxy-based silane displayed the highest performances thanks to strong interfacial interactions between epoxy functional group and isocyanate segment of TPU.

Mechanical, electrical, and melt flow properties of polyurethane elastomer/surface-modified carbon nanotube composites

Carbon nanotube-reinforced polyurethane elastomer composites were prepared by melt-mixing. Nitric acid oxidation and silanization were applied to carbon nanotube surfaces to achieve better interfacial interactions with polyurethane elastomer. Tensile and hardness tests, differential scanning calorimetry, melt flow index test, dielectric measurements, and morphological studies of composites were reported. The best results were obtained for surface-modified carbon nanotubes containing composites with lower loading levels. Addition of carbon nanotubes leads to almost two-fold increase in strain and modulus compared to pristine polyurethane elastomer. Tensile strength of composites was also improved by inclusion of carbon nanotubes. However, strength values drop down with increasing carbon nanotube content. Shore hardness increased with the inclusion of modified carbon nanotube to polyurethane elastomer while pristine carbon nanotube caused remarkable decrease in hardness of polyurethane elastomer. Relatively higher melting points and slightly lower glass transition temperatures were observed for carbon nanotube-loaded composites compared to polyurethane elastomer because of plasticizing effect of carbon nanotube. Incorparation of carbon nanotube to polyurethane elastomer matrix caused reduction in melt flow index values due to formation of agglomarates, and n the contrary, surface modifications of carbon nanotube exhibited increase in melt flow index thanks to enhanced interfacial interactions between carbon nanotube and polyurethane elastomer. Significant increase in dielectric constant of composites was observed. Better dispersion of surface modified carbon nanotubes into polyurethane elastomer was also concluded from SEM micrographs of composites.

Studies on magnetic, dielectric and magnetoelectric behavior of ( x) NiFe 1.9Mn 0.1O 4 and (1 − x) BaZr 0.08Ti 0.92O 3 magnetoelectric composites

In the present research work, the magnetoelectric (ME) composites of ferrite and ferroelectric phases with ( x) NiFe 1.9Mn 0.1O 4 and (1 − x) BaZr 0.08Ti 0.92O 3 (where x = 0.10, 0.20 and 0.30) respectively were synthesized by the conventional ceramic method. The X-ray diffraction pattern of the composite reveals a spinel phase formation for the ferrite and perovskite phase formation for the ferroelectric phase without any other phase. The SEM micrographs of composites were taken to determine the average grain size and also to study the surface morphology. The effect of constituent phase variation on the B– H hysteresis behavior and the dielectric properties was examined. The dielectric constant shows usual dielectric dispersion behavior with increasing frequency which is due to the Maxwell–Wagner type surface interfacial polarization. From the ac conductivity study, it is confirmed that the conduction in the present composites is of small polaron type. The static magnetoelectric (ME) voltage coefficient developed on the surface of magnetoelectric material was measured as a function of applied dc magnetic field. The maximum ME conversion factor of 1.18 mV/cm Oe was observed for x = 0.10 composite. Such composites may be useful to fabricate the magnetic field sensors and applicable in many linear ME devices.

Electrorheology and characterization of acrylic rubber and lead titanate composite materials

AbstractOxide one‐pot synthesis was used to synthesize a polymer precursor to lead titanate, PbTiO3. Perovskite lead titanate, PbTiO3, was synthesized via the sol–gel process. The dielectric constant, electrical conductivity and loss tangent of our acrylic rubber (AR71)–lead titanate (PT) composite material (AR/PT_8) were 14.15, 2.62 × 10−7/Ω m, and 0.093, respectively, measured at 27 °C and 1000 Hz. SEM micrographs of composites between the AR71 elastomer and PbTiO3 showed that the particles were reinforced within the matrix. The electrorheological properties of the AR71/PT composites were investigated as functions of electric field strength from 0 to 2 kV/mm and PbTiO3 particle volume fraction. The storage modulus increased linearly with particle volume fraction, with or without an electric field. Without an electric field, the particles merely acted as a filler to absorb or store additional stress. With the electric field on, particle‐induced dipole moments were generated, leading to interparticle interactions, and thus a substantial increase in storage modulus. With PbTiO3 particle volume fractions as small as 10−4 embedded in the elastomer matrix, the modulus increased by nearly a factor of 2 as the electric field strength varied from 0 to 2 kV/mm. Copyright © 2008 John Wiley & Sons, Ltd.