Abstract: Shells powder filler was added to natural rubber grade SMR L. The filler loading was varied from 60 –90 pphr. The mechanical properties included hardness and tensile strength were investigated. The results shown increased hardness continuously with shells powder filler loading from shells powder 60 –90 pphr, but tensile strength decreased after adding shells powder filler.

Abstract: Chemical functionalization of polymers after the synthesis of membranes has great importance for various applications separative processes of industrial or environmental interest. Polysulfone (PSf) is one of the most applied polymers for separative processes used especially in membrane technology, due to its excellent chemical, mechanical and thermal properties. The functionalization of PSf makes it very attractive to give special characteristics due to their high hydrophobicity and membrane fouling fast. In this work PSf perform functionalization by the method of Friedel-Crafts with choroethyl chloroacetate and subsequent hydrolysis of chloroetyl group (-OH). After synthesizing the membrane is characterized by FT-IR ATR spectroscopy, ¹HNMR, contact angle measurements, retention of polydisperse solutes and hydraulic permeability. Finally, the membranes tests fouling are performed with an oily wastewater emulsion. The fouling tests showed that the functionalized PSf membrane demonstrated significant anti-fouling property, suggesting the remarkable benefit for long-term operation in practical applications. Specifically, all the functionalized membranes reached almost 60% water flux recovery and were able to maintain the constant initial fluxes in filtration test, whereas the raw membrane only recovered 70.27% and suffered continuous decline. This promotion might be related to the increase of membrane surface hydrophilicity.

Abstract: This work is carried out to confirm the existence of the surface potentials in extracted tooth by electrochemical method. The surface potentials were measured between enamel crown’s buccal side and tooth root. Surface potentials examined in all the teeth in the presence of KCl. It is found that potential increased with increasing KCl concentration and after acid corroded. The results suggest that potentials can be affected by the surrounding electrolytes and establish an electrical double layer. It is also found that on passing electric current through enamel causes degradation.

Abstract: This work was focused on analyzing the effect produced by the addition of tannic acid as a crosslinking agent of chitosan matrix and the influence of the heat treatment applied. Taking into account those aspects relevant for packaging applications, thermal stability, mechanical properties, water resistance and kinetics of biodegradation of the film were monitored. The chemical crosslinking as well as the curing of the matrices have improved the mechanical properties and those related to the water affinity such as solubility, permeability and contact angle. Although both processes had an influence on the extent of the film degradation, these materials conserved their biodegradable character. Moreover, it was observed a synergistic effect of both chemical and physical treatments since the two processes in simultaneous caused further delay in the biodegradation. Consequently, in these materials the access to fungal attack and all those reactions mediated by the presence of water were restricted, which confirmed the higher stability of the matrices submitted to chemical or physical crosslinking.

Abstract: Friction Stir Welding (FSW) is a novel solid-phase welding process, which has proved to have a great potential for the realization of welded joints in materials with poor weldability such as heat-treatable aluminum alloys. However, the thermal cycles generated during FSW change the mechanical properties in heat affected zone (HAZ) due to two effects: over-age and re-dissolution of hardening precipitates. In other hand, the re-dissolved precipitates produce a evolution of both the microstructure and mechanical properties due to the natural aging phenomenon. The aim of this paper was to analyze the microstructural evolution in the HAZ of FSW joints in AA7075-T651 alloy. For this purpose samples FSW welded butt plate 4 mm in thickness. On the welded joint microstructural characterization was performed by light microscopy (LM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC) and Vickers microhardness profiles (HV) after different elapsed times post welding. It was observed that the hardness increases with time after welding, due to the evolution of the phases present.

Abstract: This research studies the metallurgical transformations happening during the SMAW welding of AISI 316L austenitic stainless steel with AISI 430 ferritic stainless steel. Two different electrodes, AWS E309L austenitic and AWS E2209-16 duplex stainless steels 3.2 mm diameter, were used to perform the study. The joining was made with a single pass welding and keeping a low heat input ranging from 700 - 1000 J/mm. The influence of the type of electrode and the heat input on the microstructural evolution of the heat affected and the fusion zone was evaluated. Differences between δ ferrite morphology were found for both weld metals. The heat affected zone of the ferritic side showed grain coarsening and grain refinement with martensite at the grain boundaries. Tensile strength was similar for both welding conditions. Microhardness and δ ferrite percent were measured as well.

Abstract:

Abstract: Sugarcane bagasse (SCB) is abundantly available agro-waste world-wide and has been used in different applications and its utilization as a source of cellulose attracting attention in the area of biomedical and other applications. The present study investigates the surface morphology, topography, structural, elemental and thermal properties of cellulose nanocrystals (CNCs) extracted by acid-hydrolysis from sugarcane bagasse as agro-waste. Morphological (field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM)), structural (fourier transformed infrared (FTIR) spectroscopy, X-ray diffraction (XRD)), elemental analysis (energy dispersive x-ray diffraction (EDX)) and thermal characterization (TG-DTG-DTA) of CNCs was carried out. Morphological characterization clearly showed the formation of rod-shaped CNCs having size in the range of 250-480 nm (length) and 20-60 nm (diameter). Elemental analysis (EDX) showed 0.72 wt% sulfur impurity in CNCs along with other main components. X-ray diffraction and thermal analysis revealed that CNCs have higher crystallinity (72.5%) than that of chemically purified cellulose (CPC) (63.5%) but have lower thermal stability. These lab extracted CNCs supposed to have a high potential as nano-reinforcement into bionanocomposite for biomedical and other value-added products in industrial applications.

Abstract: Single crystals of Cd_1-xZn_xTe (0 ≤ x ≤ 0.1) (CZT/CdZnTe) are used in manufacture of gamma and X-ray detectors and as substrates for epitaxial growth of HgCdTe. Computer simulation for the solidification of CZT was performed using finite elements. The simulation results indicate that a lower translation speed of the quartz ampoule within the Bridgman furnace determines a lower concavity of the liquid interface which assures a good crystalline quality. When the rate is 3.32 mm/h the concavity is 58% greater than for a speed of 0.50 mm/h. It was experimentally found that when growing at low speed, 1.66 mm/h, the process is more stable and improves the crystalline quality due that only two grains were generated in CZT ingots. Meanwhile a faster growth speed- 3.32 mm/h- generates a large amount of grains in the CZT ingot.

Abstract: In the present study two organic guest host system are being explored for electronic applications based on 2-methyl 4-nitroaniline (2-mNA)/polymethylmethacrylate (PMMA) and 2-mNA/ polyethersulfone (PES). Freestanding poled polymeric films have wide applications in nonlinear optics and in various photonics applications. Exploring dielectric capability of these films can be beneficial for many opto, electro and photonic applications. Low power loss is an essential characteristic for any electronic element and has been a challenging job for researchers and scientists. Forwarding in this direction, this paper focuses on capacitance of unpoled and poled polymeric films. Dissolving limit of guest material into polymer without showing any segration of guest material has been optimized for both host polymers. Capacitance is measured with different dose of 2-mNA by using 4294A Agilent Impedance Analyzer at room temperature. Here we are only manipulating the results that are optimized at 1K Hz frequency. It is observed that capacitance increases with increasing 2-mNA content into polymer but PMMA/2-mNA system shows more dielectric strength than PES/2-mNA system. The impact of half an hour contact poling by using 6KV/cm DC electric field at 120°C temperature on dielectric capability is also optimized. It is observed that how; to be poled the guest host films can affect the dielectric strength of both polymeric systems. Without describing electric power consumption in terms of power loss, electrical quality of any component is incomplete. Thatswhy dissipation factor have been evaluated for both guest host system at 1K Hz frequency. Dissipation factor rises with the 2-mNA doping concentration but after poled the films, it reduces drastically. PES/2-mNA system showed low power loss than PMMA/2-mNA system. The structural characterizations of all films are carried out by XRD, which shows an amorphous nature of PES/2-mNA and PMMA/2-mNA film samples. Absorbance measured by UV-Vis Spectroscopy reveals that undoped film samples has high transmittance in the UV-Vis region and doped film samples shows absorption band up to 450 nm. The films are characterized by Scanning Electron Microscopy and FT-IR Spectroscopy for bulk properties evaluation.