Polymer matrix-TiO2 composites were prepared in three different filler concentrations.The electrical relaxation dynamics as well the conductivity of all samples examined by means Broadband Dielectric Spectroscopy (BDS) over a wide frequency and temperature range.The recorded response includes contributions from both polymer matrix reinforcing phase.Two modes (β γ) are observed low region, which attributed to re-orientation polar side groups rearrangement small parts polymeric chain...

Broadband Dielectric Spectroscopy (BDS) is employed in order to investigate relaxation phenomena occurring natural rubber (NR), polyurethane (PUR) and PUR/NR blend based nanocomposites, reinforced by 10 parts per hundred (phr) Layered Silicates (LS).Nanocomposites matrices were examined under identical conditions a wide frequency (10 -1 6 Hz) temperature (-100 50°C) range.Experimental data are analyzed terms of electric modulus formalism.The recorded include contributions from both the...

Abstract Polymer matrix‐ZnO microcomposites were prepared in different filler concentrations. The electrical relaxation dynamics of all samples was examined by means broadband dielectric spectroscopy (BDS) over a wide temperature range. Two modes (namely β and γ), observed the low region, are attributed to reorientation small polar groups polymer matrix. Glass‐rubber transition (α‐mode) polymeric matrix interfacial polarization phenomena considered as responsible for recorded processes high...

We studied the symmetry and spatial uniformity of orientational order biaxial nematic phase in light recent experimental observations biaxiality thermotropic bent-core calamitic-tetramer nematics. Evidence is presented supporting monoclinic symmetry, instead usually assumed orthorhombic symmetry. The use deuterium nuclear magnetic resonance to differentiate between possible symmetries described. aspects are context cluster model, wherein macroscopic can result from field-induced alignment...

The possible symmetries of the biaxial nematic phase are examined against implications presently available experimental results. Contrary to widespread notion that nematics have orthorhombic symmetry, our study shows a monoclinic (C(2h)) symmetry is more likely be case for recently observed biaxiality in thermotropic bent-core and calamitic-tetrapode systems. methodology differentiating between by NMR IR spectroscopy measurements presented detail. manifestations different on alignment...

Abstract Ternary hybrid composites composed of polyoxymethylene (POM), polyurethane (PU) and boehmite alumina nanoparticles were produced by melt blending with without latex pre‐compounding. PU pre‐compounding was employed for the fine dispersion both particles within POM matrix. In this study electrical properties POM/PU/boehmite nanocomposites examined means broadband dielectric spectroscopy over a wide temperature (−100 to 150 °C) frequency (10 −1 10 6 Hz) range. Data analysed electric...

Abstract The dielectric properties of polyurethane (PUR) latex–boehmite alumina nanocomposites were investigated by means broadband spectroscopy in the temperature range −100 °C to 70 °C. concentration filler (alumina) was kept constant at 10 phr for all specimens, whereas mean particle diameter (namely 220, 90, and 25 nm) incorporated nanoparticles varied accordingly. For reasons comparison, pure PUR also examined. Four distinct relaxation modes recorded spectra systems. They attributed...

The mesomorphic behavior of a calamitic mesogen (4'-undecyloxybiphenyl-4-yl-4-octyloxy-2-(pent-4-en-1-yloxy)benzoate) and supermesogenic octapode formed by the side-on attachment to octasilsesquioxane central core is studied X-ray diffraction polarizing optical microscopy. compound found have nematic phase that has biaxial domains (cybotactic clusters) tilted layers throughout its entire temperature range. Domains analogous structure are also in both hexagonal columnar mesophases exhibited...

A liquid-crystalline octapode, formed by laterally connecting calamitic mesogens to an inorganic silsesquioxane cube through flexible siloxane spacers, is studied using polarized light microscopy, differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The studies are extended mixtures of the octapode with respective monomer mesogens. show a nematic phase. At lower temperatures, exhibits additionally columnar hexagonal phase (6 lattice), which, on further cooling, undergoes...

Abstract This paper reports measurements of the dielectric response over frequency range 102 to 109 Hz a liquid crystal dimer consisting two ester mesogens laterally linked by an alkoxy chain containing siloxane group. The synthesis and phase behaviour are also reported. Results show that there relaxations in isotropic four nematic material. possible molecular origins for these modes given. It is found coupling between internal external which gives rise cooperative mode as temperature...

The phase behaviour of mixtures between two symmetric dimers, CBC9CB and the ether-linked analogue CBOC9OCB was investigated by Polarizing Optical Microscopy (POM), Differential Scanning Calorimetry (DSC) X-Ray Diffraction (XRD) studies. dimeric constituents are fully miscible construction a temperature-composition diagram reveals surprising amplification stability Nx in compositions up to 37 wt% CBC9CB. origin for this enhancement is discussed an explanation based on chiral recognition developed.

Abstract Electrical relaxation and conductivity processes in amorphous semicrystalline poly(ethylene terephthalate) (PET) naphthalate) (PEN) homopolymers certain PET/PEN copolymers have been studied by means of dielectric spectroscopy. Homopolymers able to crystallize were subjected successive thermal runs investigate the influence history upon morphology electrical behavior polymeric systems. The untreated as well heat‐treated specimens was determined Differential Scanning Calorimetry...

We report the induction of Ntb phase over a wide temperature and concentration range in binary system. This was achieved by addition flexible dopant without LC properties to dimer exhibiting only nematic phase. The identified Polarising Optical Microscopy (POM), Differential Scanning Calorimetry (DSC) X-ray Diffraction (XRD) techniques.

The dielectric response of hafnium oxide nanopowder was studied in the frequency range 10−2–106 MHz and temperature 20–180 °C. Broadband spectroscopy applied experimental results were analyzed discussed using electric modulus (M*) alternating current (ac) conductivity formalisms. analyses dc data revealed presence mechanisms which are thermally activated, both with almost same activation energy 1.01 eV. A fitting procedure involving superposition activated conductivity, universal responce...

Abstract The impact of titanium dioxide (TiO 2 ) on the physical properties poly(lactic acid) (PLA) is explored, along with combined effect Atomic Layer Deposition zinc oxide (ZnO) nanocomposite films' surface. PLA/TiO bionanocomposites are prepared via melt‐extrusion and characterized in terms their morphological, thermal, mechanical properties. Homogeneous dispersion filler offers enhanced performance for samples up to 5 wt% TiO content. Thermal stability PLA also slightly improved upon...

We report on the temperature dependence of birefringence and static dielectric permittivity tensor in a series binary mixtures between symmetric, bent-shaped, 1'',9''-bis(4-cyanobiphenyl-4'-yl)nonane (CB9CB) dimer monomeric nematogen 5CB. In studied composition range exhibit two nematic phases with distinct features. Birefringence measurements are used to estimate tilt axis defining nanoscale helical modulation low phase (local) direction maximal alignment cyanobiphenyl units. Planar as well...

We present a comparative study of the optical and dielectric anisotropy laterally fluorinated liquid crystal dimer its homologous trimer, both exhibiting two nematic phases. In high-temperature phase, oligomers exhibit positive with similar magnitude, which, however, is lower in comparison monomer. same temperature range, permittivity along perpendicular to director, measured on magnetically aligned samples, reveals negative for oligomers, which saturates as approaches N-N phase transition...

Dielectric impedance measurements as well transient current–voltage (I–V) characteristics under conditions of forward and reverse bias are reported in aluminum/porous silicon (PS)∕p-cSi structures at different temperatures. Under conditions, the electrical conduction can be modeled by a simple equivalent circuit two parallel RC networks series combination, representing bulk junction region. The is ohmic. From detailed analysis PS/cSi junction, carrier concentration NA depletion layer width W...

Abstract Polyamide‐6 (PA‐6)/boehmite alumina (BA) nanocomposites were prepared via direct melt compounding. Structural, thermal and dielectric properties of ‘as‐received’ (including moisture) ‘dried’ (thermally treated) specimens examined. The BA nanofiller was homogeneously dispersed in the PA‐6 matrix. XRD FTIR revealed that crystallization γ phase favoured over α with increasing content. crystallinity index (CI) percentage phases also evaluated. Dried exhibited a lower CI than as‐received...

Impedance Spectroscopy was employed in order to investigate the electrical properties of thin porous anodic alumina films on Si, thicknesses range 50-200 nm, fabricated by anodization sulfuric acid. C–V and G–V measurements were performed voltage +5.0 V −10.0 frequency 1 MHz 100 Hz. The typical form curves a metal-insulator-semiconductor (MIS) structure obtained. effective dielectric constant ε calculated with value 6.5, good agreement previous published results. C-ω G-ω as function applied...