Effect of nanoclay and barium sulfate nanoparticles on the thermal and morphological properties of polyvinylidene fluoride nanocomposites

The thermal, morphological and optical studies of BaSO₄ and MMT (nanoclay) embedded in PVDF were investigated. Nanocomposites samples of PVDF–BaSO₄–MMT were prepared by varying the loadings (1–4 mass%) in case of BaSO₄ and MMT nanomaterials, respectively. Polyvinylidene fluoride–barium sulfate-montmorillonite (PVDF–BaSO₄–MMT) nanocomposites were prepared by solvent-mixing technique. Nanoparticles were synthesized by in situ deposition technique with the help of nonionic polymeric surfactant, and the particle size of nanoparticles was recognized by scanning electron microscopy (SEM) analysis which confirms that the particle has diameter of 80–90 nm. As prepared, nanocomposites films (thickness, 25 μm) were characterized by Fourier transform infrared microscopy (FTIR), SEM and electron diffraction spectroscopy (EDS). FTIR shows that all the chemical constituents were present in the nanocomposites, whereas SEM analysis suggested that the nanofillers dispersed well in polymer matrix and EDS showed the elemental composition of nanocomposite samples. Thermal properties of nanocomposites were studied by using TG/DTA/DTG. TG/DTA studies showed decomposition temperature of pure PVDF is 473.5 °C. The decomposition temperature (T _d) of nanocomposites was increased by 93 °C in case of nanocomposites with addition of both BaSO₄ and MMT nanomaterials. The difference in the thermal degradation temperature was found to be 1.2% higher in case of addition of BaSO₄ nanoparticle as compared to nanoclay. The obtained transparent nanocomposite films were characterized by using UV–Vis spectrophotometer which shows that transparencies of nanocomposites are maintained in visible region, the intensity of absorption band in UV region is increased with the addition of BaSO₄ nanoparticles, while in case of addition of nanoclay the UV region does not show drastic changes. Addition of both nanoparticle and nanoclay shows higher absorption in comparison with the individual samples. But further, doubling the amount of nanoparticle and nanoclay shows decrease in UV absorption. Overall, the results of thermal studies show that the incorporation of BaSO₄ and MMT could significantly improve the thermal properties of nanocomposites.     

Positive and maximal positive solutions of singular mixed boundary value problem

The paper is concerned with existence results for positive solutions and maximal positive solutions of singular mixed boundary value problems. Nonlinearities h(t;x;y) in differential equations admit a time singularity at t=0 and/or at t=T and a strong singularity at x=0.     

Topological equivalences between organic and coordination polymer crystal structures: an organic ladder formed with three-connected molecular and supramolecular synthons

[structure: see text] Crystal engineering of an organic ladder can be achieved with a T-shaped molecule, 4,4-bis(4'-hydroxyphenyl)-1-cyclohexanol, having three hydroxyl functionalities that can form O-H...O hydrogen-bonded helices. The topology of this network structure finds a parallel in three-connected coordination polymers.     

Electrical conduction mechanism in a polycrystalline Sb35Se65 sample

Localized state conduction through a variable-range hopping mechanism in the low-temperature region (～180–270 K) and thermally activated phonon-assisted tunneling in the higher-temperature region (～270–320 K) has been observed in a polycrystalline Sb₃₅Se₆₅ sample.     

On finite anti-plane shear for compressible elastic circular tube

Knowles' theorem for anti-plane shear of compressible, homogeneous, isotropic elastic materials in finite elastostatics is used to determine some restrictions on a strain-energy density function characterizing materials for which two anti-plane shear problems of a circular tube are then solved exactly.

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Resumé Le theorème de Knowles pour le cisaillement anti-plane de matériaux compressibles, homogénes, isotropes, élastiques en élastostatique finie est utilisé afin de déterminer certaines restrictions sur un fonction-densité d'énergie de déformation caractérisant des matériaux pour lesquels deux problèmes de cisaillement anti-plan d'un tube circulaire sont alors résolus exactement.