Preparation and Characterization of a New Polymeric Multi-Layered Material Based K-Carrageenan and Alginate for Efficient Bio-Sorption of Methylene Blue Dye

The current study highlights a novel bio-sorbent design based on polyelectrolyte multi-layers (PEM) biopolymeric material. First layer was composed of sodium alginate and the second was constituted of citric acid and k-carrageenan. The PEM system was crosslinked to non-woven cellulosic textile material. Resulting materials were characterized using FT-IR, SEM, and thermal analysis (TGA and DTA). FT-IR analysis confirmed chemical interconnection of PEM bio-sorbent system. SEM features indicated that the microspaces between fibers were filled with layers of functionalizing polymers. PEM exhibited higher surface roughness compared to virgin sample. This modification of the surface morphology confirmed the stability and the effectiveness of the grafting method. Virgin cellulosic sample decomposed at 370 °C. However, PEM samples decomposed at 250 °C and 370 °C, which were attributed to the thermal decomposition of crosslinked sodium alginate and k-carrageenan and cellulose, respectively. The bio-sorbent performances were evaluated under different experimental conditions including pH, time, temperature, and initial dye concentration. The maximum adsorbed amounts of methylene blue are 124.4 mg/g and 522.4 mg/g for the untreated and grafted materials, respectively. The improvement in dye sorption evidenced the grafting of carboxylate and sulfonate groups onto cellulose surface. Adsorption process complied well with pseudo-first-order and Langmuir equations.

Analysis of Surface Degradation of Silicon Rubber Insulators after 30 Years in-Service

In recent years, polymeric insulators have been increasingly used for high voltage overhead transmission lines. The industry has replaced the insulators from ceramic to polymeric due to its lightweight and hydrophobic materials, not to mention the performance against pollutant contamination. In this study, an analysis of two 70 kV silicone rubber insulators is performed. The insulators had been in service for 30 years on transmission networks in volcanic area, exposed to intense UV solar radiation in midday, but also high precipitation occur throughout the year. The urge to understand better of polymeric aging behavior is important to improve the quality of the polymeric type insulators. In this study, these aged samples were then compared with virgin samples to identify the endurance and quality of polymer material. The surface deterioration and the change of chemical content were evaluated using advanced techniques, including Spectroscopy and Scanning Electron Microscopy (SEM), Energy-dispersive X-ray Analysis (EDX), Thermo-Gravimetric Analysis (TGA), and Fourier Transform Infrared (FTIR). Meanwhile, the hydrophobic and visual inspection were also conducted. The hydrophobicity was evaluated by measuring the contact angle and assessed using IEC62073. The aged samples are categorized as hydrophobic class 1 due to the angle value of more than 60o. Physicochemical results showed that the aged sample compared with the virgin simple did not differ significantly given that the aged samples have been in-service for 30 years. Based on TG/DTA result, the percentage difference of weight loss between virgin and aged sample only lower than 4%. Then, from EDX result, the atomic percentage differences of C and O component compared with virgin sample are 4%-10%. Furthermore, the FTIR spectra indicates a normal aging condition of the silicone rubber, the difference in peak value of Si-(CH3)2 and OH compared with virgin sample is 10%.

On Experimental Thermal Analysis of BMC Mensolite 3100 Aging

The paper is devoted to the study of thermal parameters (specific heat capacity, diffusivity and thermal conductivity) changes after thermally induced aging of BMC Mensolite 3100. Results of several measurements are statistically treated. From obtained results it is visible the greatest correlation in the diffusivity values, i.e. the heat irradiation effect is the smallest on the diffusivity values dispersion, the influence of the heat irradiation on the thermal capacity has approximately the same trend as the thermal conductivity. From the starting point represented by the virgin sample both values decrease and for the sample heated at 300°C it is visible an increase of the above mentioned values under investigation. Results are interpreted by using of the thermogravimetric analysis (TGA). All physical values under this investigation have a dominant decreasing tendency after the thermal treatment described.

Discotic liquid crystals of transition metal complexes 46: mesomorphism and antagonist solubility of octaphenoxy-phthalocyaninato copper(II) complex substituted by oligoether chains

We synthesized a novel discotic liquid crystalline compound, octakis[3-(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)phenoxy]phthalocyaninato copper(II) (abbreviated as [m- MeO(EtO)3PhO]8PcCu ), and established the mesomorphism by using a differential scanning calorimeter, a polarizing optical microscope, and temperature-dependent wide angle X-ray diffraction diffractometer. Very interestingly, this [m- MeO(EtO)3PhO]8PcCu complex showed a hexagonal ordered columnar (Colho) mesophase in the virgin sample, whereas it showed a rectangular ordered columnar (Colro(P21/a)) mesophase in the non-virgin sample. The Colho mesophase gave a dimer stacking distance at 9.26 Å, whereas the Colro mesophase gave a short monomer stacking distance at 3.45 Å. Furthermore, this novel Pc derivative is readily soluble in polar solvents such as acetone, ethanol and methanol. Using antagonist solubilities of the present hydrophilic [m- MeO(EtO)3PhO]8PcCu derivative in a polar solvent and the previous hydrophobic (C10O)16TzCu derivative in the non-polar solvent, a p-n junction layered thin films could be successfully prepared.

The Influence of Excess Nitrogen, on the Electrical Properties of the 4H-SiC/SiO2 Interface

The effect of nitrogen (N) introduced by ion implantation at the SiO2/4H-SiC interface on the capacitance of the MOS capacitors is investigated. The Thermal Dielectric Relaxation Current (TDRC) technique and Capacitance-Voltage (C-V) measurements performed at different temperatures and probe frequencies on an N implanted sample and on a virgin sample were employed for this purpose. There are three types of defects located at or near the interface, Dit, NIToxfast and NIToxslow that can be distinguished. Only Dit and NIToxfast respond to the a.c. small, high frequency signal at temperatures above 150K. The separation of Dit from the NIToxfast states have enabled us to study the influence of the excess of interfacial Nitrogen on each of the mentioned defects. It has been found that the N-implantation process fully suppresses the formation of NIToxfast and partially NIToxslow and Dit. Theoretical C-V characteristics were computed, based on the defect distributions determined by TDRC, and compared with the experimental ones showing a close agreement.

Preparation and Study Hardness and Thermal Conductivity (Tc) to Polyester Resin Composite with (Titanium Dioxide, Zinc Oxide, Acrylonitril, Wood Flour Coconut

This study is attempt to improve thermal isolation through measuring thermal conductivity composite of on polyester resin with fillers of (TiO2, ZnO, Acrylonitril, wood flour Coconut (Wf). The grain size of the fillers is 200 µm. The number of samples is (16) in addition to the virgin sample; these samples are prepared by cast molding method for polyester with filler volume fractions (5%, 10%, 15% and 20%). Shore hardness tests were used to measure the hardness and Lee disk method for thermal conductivity. The experimental results showed that the (20% ZnO) sample has the maximum value of thermal conductivity where (20% w.f) has minimum thermal conductivity .on the other hand (15% ZnO) sample give the maximum value of hardness where (20% w.f) sample gave the minimum value of hardness. From this study there is an important factor that should be observed that is the relationship between hardness and thermal conductivity. The study prove that the experimental results satisfy the theoretical assumptions in that the additive material (fillers) of metals base increase thermal conductivity where the material of cellulose base decrease the thermal conductivity and give good thermal isolation but with low hardness and all the result above the refry sample .

A nanoindentation study on grain-boundary contributions to strengthening and aging degradation mechanisms in advanced 12 Cr ferritic steel

Nanoindentation experiments and microstructural analysis were performed on advanced 12% Cr ferritic steel having extremely fine and complex martensitic microstructures, to answer unsolved questions on the contributions of grain boundaries to strengthening and aging degradation mechanisms in both as-tempered and thermally aged steels. Interesting features of the experimental results led us to suggest that among several high angle boundaries, block boundary is most effective in enhancing the macroscopic strength in as-tempered virgin sample, and that a decrease in matrix strength rather than reduction in grain-boundary strengthening effect is primarily responsible for the macroscopic softening behavior observed during thermal exposure.

Inhomogeneous nano-mechanical properties in the multi-phase microstructure of long-term aged type 316 stainless steel

Microstructure-related local deformation behavior was evaluated using nanoindentation techniques for a type 316 austenitic stainless steel used in energy generation plants. The sample was aged for 39,332 h (4.5 years) at 700 °C. The microstructure included the σ phase precipitated at grain boundaries and in grain interiors. The nanohardnesses of the σ phase and the matrix in the aged and virgin samples were evaluated quantitatively. The hardness of the σ phase was found to be extremely high in the order of 17 GPa, which is much higher than the value of about 3.4 GPa for the matrix in the aged sample. The hardnesses of the σ phase at the grain boundary and the adjoining matrix were the same as those in the grain interior. Moreover, the hardness of the matrix of the aged sample was about 30% lower than that of the virgin sample while the Vickers hardness as a macroscopic strength of the aged sample was about 45% higher than that of the virgin one. The deformation and fracture behavior in a local region was discussed in terms of the inhomogeneous mechanical properties in the multi-phase microstructure.

Effect of Recycling on the Rheological Properties and Foaming Behaviors of Branched Polypropylene

The effects of recycling of branched polypropylenes on their rheological properties and foamability are studied in this paper. The rheological properties and foamability of branched polypropylene are compared with those of the virgin sample. The main purpose of the study was to explore the possibility of using recycled materials to make the acceptable foam products. The recycled polypropylenes showed the lower melt strength due to the lowered molecular weight and disentanglement of molecules. However, the high-shear viscosities of the virgin and recycled resins exhibited almost the same values whereas the zero-shear rate viscosity was lower for recycled ones. The rheological behavior of the resins was correlated to the foaming behavior. It was observed that the contribution of the storage modulus (G’) was more pronounced than the loss modulus (G”). The foam morphology of recycled branched polypropylene and the virgin material was studied at various processing temperatures using a single-screw tandem foam extrusion system. The volume expansion ratio and cell population density results were correlated with the rheological data. Despite the noticeable drop in the melt strength, it was found that the foamability did not significantly deteriorate by recycling.

Characterization of n-type layer by S+ ion implantation in 4H-SiC

ABSTRACTWe investigated the optical, electrical and structural properties of the layer which was implanted with sulfur ion(S+) in 4H-SiC. By using the high temperature ion implantation technique more less residual defects were observed compared with the room temperature ion implantation by Rutherford backscattering spectrometry and channeling(RBS-channeling). After annealing at 1700°C there was no significant difference between the implanted sample and virgin sample in crystallinity within the detection limit of RBS-channeling. From the result of low temperature photoluminescence(LTPL) we could see the photoluminescences, so-called D1 and D2center, originating in the defects formed by ion implantation and post-annealing(∼1700°C) processes and confirmed that their intensities decreased with the increasing of the total dose of S+. The result of Hall effect measurement suggested that the conduction type of S+-implanted layer is n-type and their activation energies were 275meV and 410meV by the fitting of neutrality equation assuming the two activation energies for the hexagonal and cubic lattice sites in 4H-SiC.