Modification of PTFE flat sheet film via radiation induced grafting polymerization with acrylic acid

Polytetrafluoroethylene (PTFE) flat sheet film was modified with acrylic acid (AAC) by radiation induced grafting polymerization (RIGP) method using electron beam. The adsorbed doses were varied from 10 to 50 kGy, time of grafting from 1 to 3 h and monomer concentration and temperature were kept constant at 30 wt. % and 40ºC. The degree of grafting (Dg) and equilibrium degree of swelling (EDS) of the grafted films were then determined. The films were further characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), atomic force microscope (AFM), X-ray diffraction (XRD), and optical water contact angle. Dg within the range of 17% to 210% were obtained for doses from 10 to 50 kGy within time of grafting from 1 to 3 h. The grafted film (PTFE-g-AAC) showed increased hydrophilicity leading to an increase in EDS. The successful grafting process was confirmed by FTIR results that showed characteristics peaks for carbonyl and hydroxyl group and a decrease in crystallinity for the PTFE-g-AACfilm. SEM images showed that PTFE-g-AAC films had less fibrillar compared to PTFE film and was consistent with the decrease in roughness for the PTFE-g-AAC film. This study indicated that modifying PTFE film by grafting AAC could significantly improve the hydrophilicity of PTFE film. The PTFE-g-AAC films has potential as a heavy metal adsorbent as it can remove at least 75% of Fe ion and 50 % of Pb ion from competitive media

Impact of europium concentration on thermal and absorption features of amorphous tellurite media

Improving the structural and optical properties of tellurite glasses via optimized doping of rare earth ions is an outstanding issue in materials science. Tellurite glasses doped with trivalent europium (Eu3+) are successfully prepared using conventional melt quenching technique. Glasses with chemical composition of (80-x)TeO2-10PbO-10ZnO-(x)Eu2O3 where 0 ≤ x ≤ 2.0 mol% are obtained. The influence of Eu3+ ions concentration on the thermal and absorption properties of the synthesized glasses is investigated using Differential Thermal Analyzer (DTA) and UV-VIS Spectroscopy. DTA curves in the temperature range of 50-1000 °C at a heating rate of 10 °C/min are used to determine the temperature of glass transition, crystallization, melting and in turn the thermal stability. DTA revealed that the increase in the Eu3+ contents improved the thermal stability. This observation is attributed to the alteration of the glass network structure via the creation of non-bridging oxygen. The room temperature absorption spectra recorded in the spectral region of 200 – 2000 nm exhibited three absorption peaks corresponding to 7F0 → 5D0, 7F0 → 5D1 and 7F0 → 5D2 transitions. The absorption intensity is found to be enhanced up to certain concentration of Eu3+ ions and then quenched. This is ascribed to the change in glass network structure and formation of defects through the cleavage of weak bonds and reduction in covalence states

Identifying uniform corrosion of carbon steel using electrochemical noise measurement / Shirley Arvilla Andrew, Khaidzir Hamzah and Tammie Christy Saibin

In this study, the electrochemical noise (ECN) measurement technique was utilized to identify the uniform corrosion of carbon steels in the solutions of hydrochloric (HCl), sulphuric (H2SO4), sodium chloride (NaCl), sodium hydroxide (NaOH), potassium hydroxide (KOH) and calcium hydroxide (Ca(OH)2). ECN is the fluctuations of current and potential of a corroding system. The potential of electrochemical noise was measured between a working electrode and a reference electrode whereas the current of electrochemical noise was measured between two working electrodes in an electrochemical cell. The data from the measurements were statistically analyzed using time and frequency domains. The time domain analysis reveals the characteristics of a particular corrosion type. The frequency domain analysis estimates the power spectra at various frequencies and the statistical analysis calculates electrochemical noise parameters such as the mean, standard deviation, noise resistance (RN), coefficient of variation (CoV), characteristic charge (q) and corrosion current (Icorr). The results of the time domain analysis show that uniform corrosion only occurred in acidic solutions of HCl and H2SO4. The frequency domain analysis was found to be an unsuitable method to identify uniform corrosion in the corrosion system used. The statistical analysis shows that the corrosion rate was greater when using the solutions of HCl and H2SO4 compared to NaCl, NaOH, KOH and Ca (OH)2

Dynamic testing for compatibility assessment of non-metal automotive components with biodiesel fuel: a concept study

Over the years, concern on the compatibility issue of the blended biodiesel fuel with non-metal material components in diesel engine vehicles had received many attentions. Assessing the compatibility of non-metal material components like elastomer and plastics usually rely on the measurement of mechanical and physical properties such as tensile strength, elongation, hardness, surface morphology, weight and volume changes. These properties are typically measured after the static immersion test is done accordingly to the ASTM D471. However, data and results given from the static immersion test is only applicable when the samples are in a static condition and not in a dynamic situation. Thus, this paper attempts to review some common issues related to the biodiesel fuel and non-metal components and introducing the dynamic testing approach that can be applied when assessing the compatibility study of biodiesel fuel with some potential problems that might be encountered

Fabrication parameters dependent morphology variation of silicon thin film

Achieving two dimensional quantum structure of silicon with welldefined tuneable morphology is an outstanding issue. We present the preliminary results on fabrication parameters dependent silicon thin film production using VHF-PECVD method. Five samples are prepared on Si(100) substrate with gold (Au) catalyst by adjusting different parameters such as deposition time, temperature and the flow of precursor gas. The samples morphology are analysed using FESEM. The results reveal that the silicon thin film appear to be smooth and crystal-like after an enormous amount of hydrogen is inserted together with the precursor gas (silane) during the deposition process. More interestingly, the films exhibit silicon nanowires as the deposition time is increased up to 1 hour. This morphological transformation is attributed to the vapour-liquid-solid (VLS) mechanism related to the deposition process. Our results may contribute towards the development of nanosilicon based optoelectronics

Nigeria research reactor-1 : vertical detector efficiency calibration using conventional and semi-empirical approach for large samples NAA implementation

Detector efficiency calibration is mandatory for accurate measurement of induced activity in irradiated samples and for safe operation of the reactor with minimal uncertainty. This paper reported the efficiency calibration of vertically dIpstick High Purity Germanium detector, installed at the Centre for Energy Research and Training, Ahmadu Bello University Zaria for the purpose of large sample Neutron Activation Analysis (NAA) using Nigeria research reactor-1 (NIRR-1). The performance of the detector was evaluated for the radioisotope activity measurements during the reactor operation for large samples neutron activation analysis. The detector performance in terms of radioisotopes detection ability was inspected using the standard conventional and semi-empirical approaches. The full energy peak efficiencies were determined at the corresponding energies for three different geometries (source to detector distance of 1, 5 and 10 cm). The semi-empirical approach produced better and precise results that logically rhymed with theory than the traditional approach. Besides that, a consistency in the nature of the graphs and values were evidenced. The determined efficiencies and their corresponding energies revealed encouraging outcome and ensured the successful NAA for large samples of different material compositions

A review on preparation and characterization of silver/nickel oxide nanostructures and their applications

Nickel oxide and silver oxide nanoparticles have wonderful properties that could be employed in numerous applications. Thus, synthesis of nickel silver oxide nanostructures with different characteristics is of great interest. In this review, many synthesis methods were reported such as: electrodeposition, electrochemical method, simple immersion process and subsequent RFsputtering deposition, chemical oxidative polymerization, followed by acidic sol–gel process, flame-based process, liquidphase reduction technique, sol–gel, hydrothermal method, co-precipitation method, simple precipitation method, thermal decomposition, chemical wet synthesis, low and high-temperature reduction, high-pressure autoclave, thermal treatment method, and laser-liquid–solid interaction technique. Reporting all methods employed for the fabrication of NiO and Ag2O nanostructures is useful to produce and develop novel nanomaterials with enhanced properties and applications. Studying the factors that tuned their properties: particle size, shape, and capping agents as well as solution pH is highly recommended in future works. Also, further research studies should be conducted for finding another/other facile and effective synthesis method/methods

Optimal nuclear trigeneration system considering life cycle costing

A nuclear reactor can generate a large amount of high-temperature waste heat, which can be recovered to produce simultaneous electricity, heating and cooling, known as a trigeneration system. Trigeneration System Cascade Analysis is a methodology based on Pinch Analysis to optimise a centralised trigeneration system in various energy ratings in demands. However, the previous study does not consider a complete life cycle costing in the Trigeneration System Cascade Analysis. The methodology consists of three main parts, which are data extraction, development of Trigeneration System Cascade Analysis, and calculations of the life cycle costing. In this analysis, a centralised Pressurised Water Reactor, which is the most commonly used nuclear reactor in the world, is applied in a trigeneration mode in three different industrial plants. Based on the results of the case study, an optimal Pressurised Water Reactor trigeneration system is obtained where the total thermal energy required is 1,102.25 MW or translated into 26.5 GWh/d. The Equivalent Annual Cost for the case study, on the other hand, showed the centralised Pressurised Water Reactor trigeneration system requires 1.89 × 1011 USD/y for maintaining, operating, constructing, and disposing of the overall Pressurised Water Reactor trigeneration system. The maintenance cost is the highest percentage which constitutes 51.3% of the overall cost. Comparisons between normal conditions, and planned and unplanned shutdowns are also conducted, and the results show that Equivalent Annual Costs of planned and unplanned shutdowns required an additional 1.4 MUSD and 0.5 MUSD to support the deficit energy during shutdowns. The implementation of the full life cycle costing during the normal conditions planned and unplanned shutdowns of the Pressurized Water Reactor trigeneration system gives a proper projection of the cash flows that can create an economic model that reflects all the project realisation conditions

Binary nickel and silver oxides by thermal route: preparation and characterization

Many studies have concentrated on exploring behaviors of nickel silver oxide nanoparticles using various routes of fabrication. Thermal treatment technique has never been utilized to fabricate nickel oxide silver oxide nanoparticles. In this research, binary (NiO)0.4 (Ag2O)0.6 nanoparticles were synthesized using the thermal treatment method due to its attractive advantages such as low cost, eco-friendly, and purity of nanoparticles. The structural, morphological, and optical behaviors of these nanoparticles were investigated at different calcined temperatures. X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), ultraviolet–visible spectroscopy (UV–Vis), and photoluminescence (PL) were the techniques used to characterize the synthesized nanoparticles. XRD was conducted at different calcined temperatures. The crystallite size was increased from 25.4 nm to 37.0 nm as the calcined temperature increased from 500 °C to 800 °C. Also, TEM results verified that the mean particle size was enlarged as the calcined temperatures increased. Two band gaps were found for each temperature, which were decreased from (3.05, 2.45) to (2.70, 1.95) eV as the temperature varied from 500 to 800 °C, respectively. Broadbands were observed by PL spectra, and the intensity of two emission peaks was also increased at higher temperatures. The results approved the successful formation of binary (NiO)0.4 (Ag2O)0.6 nanoparticles by a novel facile synthesis route. These nanoparticles are likely to have various applications, especially optical applications due to the formation of two band gaps