Self-assembled 1-octadecyl-1H-1,2,4-triazole films on copper for corrosion protection

A film of 1-octadecyl-1H-1,2,4-triazole (OTA) was formed on a fresh copper surface by self-assembly technique. The optimum concentration of OTA and immersion time for the formation of a protective OTA film have been established using electrochemical impedance spectroscopy (EIS). These are (i) 15 mM concentration of OTA in methanol and (ii) immersion period of 48 h. X-ray photoelectron spectroscopy (XPS), reflection absorption FTIR spectroscopy, atomic force microscopy (AFM), and contact angle measurements have been used to characterize the OTA film on copper surface. The efficiency of OTA film to protect copper from corrosion in aqueous NaCl environment has been investigated using EIS, potentiodynamic polarization studies, cyclic voltammetry and weight-loss studies. All these studies showed that the OTA film affords excellent protection against corrosion of copper.     

Barium Salts of Tetrazole Derivatives – Synthesis and Characterization

The compounds barium tetrazolate ( 6 ), barium 5‐aminotetrazolate tetrahydrate ( 7 ), barium 5‐nitriminotetrazolate dihydrate ( 8 ), barium bis(1H‐5‐nitriminotetrazolate) tetrahydrate ( 9 ), barium 1‐methyl‐5‐nitriminotetrazolate monohydrate ( 10 ), and barium 2‐methyl‐5‐nitriminotetrazolate dihydrate ( 11 ) were synthesized by the reactions of barium hydroxide octahydrate and 1H‐tetrazole ( 1 ), 5‐aminotetrazole ( 2 ), 1,4H‐5‐nitriminotetrazole ( 3 ), 1‐methyl‐5‐nitriminotetrazole ( 4 ), and 2‐methyl‐5‐nitraminotetrazole ( 5 ), respectively. The compounds were characterized using multi‐nuclear NMR spectroscopy, vibrational (IR and Raman) spectroscopy, elemental analysis, and differential scanning calorimetry. The solid‐state structures of 7 – 11 were determined using low temperature X‐ray diffraction and a comprehensive characterization is given. In addition, the sensitivities (impact, friction, electrical discharge) of 6 – 11 were investigated and bomb calorimetric measurements were carried out.     

Using hop bines as reinforcements for lightweight polypropylene composites

Whole hop bines (HBs), the peeled outer bark (OB) of HBs, and fibers chemically extracted from hop bark (HFs) were used as reinforcements to make lightweight composites with polypropylene (PP) webs or fibers as the matrix materials. Using discarded HBs for composites not only increases the value of hop crops but also provides a green, sustainable, and biodegradable material for the composite industry. Lightweight composites are preferred, especially for automotive applications because of the potential energy savings. In this research, the effects of the processing parameters on the properties of PP composites reinforced with HBs were studied. The composites reinforced with OB without any chemical treatment showed better properties than the composites reinforced with HFs or HBs. Compared with jute–PP composites of the same density (0.47 g/cm³), composites reinforced with OB had 43% higher flexural strength, 46% higher impact resistance, 56% higher Young's modulus, similar modulus of elasticity, 33% lower tensile strength, and better sound‐absorption properties. OB–PP composites with optimized properties have the potential to be used in industrial applications such as support layers in automotive interiors, ceiling tiles, and office panels. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and characterization of poly(vinyl alcohol)/water glass (SiO2) nano‐hybrids via sol‐gel process

A new class of materials based on inorganic and organic species combined at a nanoscale level has received large attention recently. In this work the idea of producing hybrid materials with controllable properties is applied to obtain foams to be used as catalyst supporting. Hybrids were synthesized by reacting poly(vinyl alcohol) in acidic solution with water glass. The inorganic phase was also modified by incorporating a hexamethyldisiloxane as precursor. The hybrid aerogel powder was analyzed by scanning electron microscopy, TG‐DTA, Nitrogen adsorption–desorption, X‐ray diffraction and fourier transform infrared spectroscopy (FTIR) spectroscopy. The powder obtained had a higher porosity varying from 65 to 90% and the nanopore diameter ranged from 17 to 20 nm. The surface area and nanopore volume decreased as polymer content increased in the hybrids. The sharp decline in the weight observed at around 500°C accompanied an exothermic peak of the DTA curve. The sharp peak was observed around 211°C represents the DTA curve of Poly vinyl alcohol constituent in nano hybrids. The peak at 1638 cm^?1 in the FTIR indicated the formation of Si? O? PVA? O? Si bridge in aerogel powder. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

A study on ligno‐cellulosic fabric Hardwikia binata

A naturally occurring fabric belonging to the species Hardwikia binata was extracted from the sheath of stem, bark, and branches of the tree. The fabric specimens were treated with sodium hydroxide and poly (vinyl alcohol). The morphology of the fabric specimens before and after NaOH treatment was studied using scanning electron microscopy technique. Ligno‐cellulosic properties of fabric were analyzed by XRD, FTIR, and thermo gravimetric methods before and after NaOH treatment. Tensile strength and percentage of elongation at break of the fabric were also studied by using a universal testing machine (model AGS‐10kNG). The results showed that the poly (vinyl alcohol)‐treated fabric specimens showed higher tensile strength than sodium hydroxide‐treated fabric specimens. The Binata fabric has good thermal resistance and was also found to increase by alkali treatment. The FTIR method indicates lowering the hemi cellulose and lignin content by alkali treatment in the fabric. Further, the X‐ray diffraction studies revealed an increase in crystallinity of the fabric by alkali treatment. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Recovery of Na2SO4·10H2O from a reverse osmosis retentate by eutectic freeze crystallisation technology

The increasing amount of waste water and effluent from South Africa's mining industry forms a growing problem, which processing requires sustainable solutions in which both the water and the dissolved component can be re-used. Eutectic freeze crystallisation (EFC) has been identified as a key technology that is not only energy efficient, but also produces ice and salt products of high quality. Unlike reverse osmosis membrane systems, EFC can treat both dilute and concentrated systems minimising waste water volumes. In this paper it is shown that freeze and eutectic freeze crystallisation can be used for the processing of a reverse osmosis retentate stream containing 4% NaSO₄ and a number of impurities (F, Cl, K, Li, Mg, Ca, NO₃ and NH₄), producing both pure water and NaSO₄·10H₂O crystals. The influence of the impurities on the eutectic point and on the crystal structure of mirabilite was investigated using EFC technology investigated for a pure binary system, for a synthetic reverse osmosis retentate as well as for a concentrated NaCl system. In addition, investigations into the recovery and purity of mirabilite for these streams were conducted.     

Study of variables affecting the synthesis of biodiesel from Madhuca Indica oil

Biodiesel derived from non‐edible Madhuca Indica oil (MIO) seems to be a better alternative to diesel oil in India. In the present work, effects of reaction variables such as mass ratio of methanol to oil, catalyst concentration, reaction time and reaction temperature on biodiesel yield were studied. The acid value of the commercially available MIO is high, and hence a two‐step process was used to produce biodiesel from MIO. In the first step, the acid value of the MIO was reduced to less than 1 mg KOH/g, using acid‐catalyzed transesterification. In the second step, the pretreated MIO was converted to biodiesel using alkaline‐catalyzed transesterification. From the experimental results, it is observed that the optimized conditions for biodiesel production are a 1 : 4 mass ratio of methanol to oil, 55 °C reaction temperature, 120 min of reaction time, and 1% sodium hydroxide catalyst. The properties of the MIO biodiesel were found to be within the biodiesel limits of the European Union. Hence, the MIO biodiesel can be used as a substitute for diesel for the sustainable development of rural areas and as a renewable fuel.     

Direct torque control of induction motor based on advanced discontinuous PWM algorithm for reduced current ripple

In recent years several discontinuous pulse width modulation (DPWM) methods are reported to improve the performance of AC drives at high modulation indices. It is proved that the performance of the popular PWM methods is modulation index dependent and no single DPWM method provides satisfactory performance over the entire high modulation range. Two popular existing DPWM methods renowned with the names DPWMMIN, DPWMMAX clamp each phase for 120° duration in every cycle of its fundamental voltage. It is observed that only the zero state is different in these two sequences. In this paper, it is proposed that, utilizing these two DPWM sequences and by changing the zero state at any spatial angle γ, where γ is between 0° and 60°, an infinite number of DPWM sequences including the existing DPWM methods and advanced DPWM (ADPWM) methods can be generated which are categorized as “continual clamping” and “split clamping” sequences. Using these ADPWM techniques an optimal split clamping sequence-based DTC of induction motor is proposed. With the proposed DTC method it is shown that steady state line current distortion at higher line side voltages is reduced significantly compared with the CDTC as well as conventional SVPWM (CSVPWM)-based DTC.     

Fabrication of copper–TiC–graphite hybrid metal matrix composites through microwave processing

The significant requirements such as wear resistance and better tribological properties in addition to good electrical conductivity necessitate the development of copper-based advanced metal matrix composites for electrical sliding contact applications. Though the addition of graphite to copper matrix induces self-lubricating property, the strength of the composite reduces. The improvement in the strength of the composite can be achieved by reinforcing harder ceramic particles such as SiC, TiC, and Al₂O₃. In this paper, the development of hybrid composite of copper metal matrix reinforced with TiC and graphite particles through microwave processing was investigated. The effects of TiC (5, 10, and 15 vol.%) and graphite (5 and 10 vol.%) reinforcements on physical and mechanical properties of microwave-sintered copper–TiC–graphite hybrid composites are discussed in detail. Micrographs show the uniform distribution of reinforcements in copper matrix. Microwave-sintered composites exhibited higher relative density, sintered density, and hardness compared with conventionally sintered ones.