Synthesis,characterization, and thermal properties of cyanate esters with azo linkages

A series of azo functionalized diols were synthesized through diazotization which involves the reaction of amine with phenol and 2,6‐dimethyl phenol. Four different amines have been used to prepare five bisphenols. These bisphenols were converted to their corresponding cyanate esters by treatment with cyanogen bromide (BrCN) in the presence of triethylamine (Et₃N). The chemical structures of the prepared compounds were characterized with Fourier Transform Infrared, ¹H‐NMR, ¹³C‐NMR spectroscopy, and elemental analysis. Dynamic curing behavior was investigated using differential scanning calorimetry. The maximum curing temperature of these cyanate esters are in the range of (186–208°C). T_g values of the polycyanurate networks are in the range of 245–276°C. The thermal properties of cured cyanate ester were studied at a heating rate of 10°C min^?1 in N₂ atmosphere. The polymers showed excellent thermal stability (T₁₀ was found to be in the range 405–438°C) and the percentage of char yield at 800°C were found to be 30–49. The flame retardancy of the cyanate ester resins have been studied using limited oxygen index value which is in the range of 29.5–37.1 at 800°C. POLYM. ENG. SCI., 55:47–53, 2015. © 2014 Society of Plastics Engineers     

Experimental studies on solar parabolic dish cooker with porous medium

The solar cooking is the alternate method of cooking to reduce consumptions of fossil fuels. An affordable, energy efficient solar cooking technology is much need due to the fossil fuels increasing cost and it is the hottest research topic in all over the world. This paper presents an experimental analysis of the heat transfer enhancement of solar parabolic dish cookers by a porous medium made of scrap material. Using the stagnation temperature test and water boiling test are conducted on the cooking vessel with and without porous medium. Experimental results are compared for both cases in terms of thermal performance, optical efficiency, heat loss factor and cooking power.     

Planar perovskite solar cells: eco-friendly synthesized cone-like ZnO nanostructure for efficient interfacial electron transport layer

The process of interfacial engineering in planar perovskite solar cells (PPSCs) plays an important role not only in transferring charges from active perovskite layer but also in enhancing the device performance. Considering this, the present study aims to synthesize an eco-friendly solution processed ZnO nanostructure interfacial electron transport layer (ETL) in PPSCs. The optical, structural, morphological and chemical properties of the prepared ZnO nanostructured material are analysed using ultraviolet–visible spectroscopy (UV–Vis), X-ray diffraction analysis (XRD), field emission-scanning electron microscopy (FE-SEM), energy-dispersive X-ray analysis (EDX), Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) analysis, respectively. Under ambient conditions, the device performance in terms of efficiency, stability and device degradation are investigated for both single layer (c-TiO₂ and cone-like ZnO nanostructure) and bilayer (c-TiO₂/cone-like ZnO nanostructure) ETL. Furthermore, the effective way of constructing cone-like nanostructured ZnO ETL on top of c-TiO₂ surface, found to be improved in faster charge transfer at the ETL/perovskite interfaces and reduced recombination losses. As a result, it exhibits maximum power conversion efficiency (PCE), short-circuit current density, fill factor and open-circuit voltage as 8.02%, 15.33 mA cm^?2, 0.52% and 0.99 V, respectively. Besides, the stability of PPSCs fabricated with bilayer exhibits better air stability of?~?87.40% with retained rate of 250 h from its initial value.

     

Green-Inspired Fabrication of Silver Nanoparticles and Examine its Potential In-Vitro Cytotoxic and Antibacterial Activities

Journal of Inorganic and Organometallic Polymers and Materials - The present work demonstrates the non-hazardous and environmentally benevolent green fabrication of silver nanoparticles using...     

Synthesis and characterization of poly(arylene ether) containing cyanate ester networks

A series of bisphenols containing ether linkage were prepared from halo phenol/dihalo compound and dihydroxy compounds in the presence of K₂CO₃. The bisphenols were transformed to cyanate esters by treatment with cyanogen bromide using triethyl amine catalyst. The structure of all the five bisphenols and the cyanate esters were structurally confirmed by FT-IR, ¹H-NMR and ¹³C-NMR spectral methods and elemental analysis. The cyanate esters were cured at 100 °C (30 min) → 150 °C (30 min) → 200 °C (60 min) → 250 °C (3 hr). The thermal properties of the cured resins were studied by DSC and TGA. DSC analysis shows that these cyanate esters exhibit T _g in the range of 203–234 °C. The CE(c) has the highest glass transition temperature. The cyanate ester CE(e) shows the lowest T _g which is due to its asymmetric structure. The initial degradation temperature of the cured resins was found to be in the range of 324–336 °C. The Limiting Oxygen Index (LOI) value, determined by Van Krevelen’s equation, is in the range of 35.5–38.7.     

Polyphenolic and phytochemical content of Cucumis sativus seeds and study on mechanism of preservation of nutritional and quality outcomes in enriched mayonnaise

Oxidative rancidity in food emulsions leads to a reduction in shelf life. Synthetic antioxidants are widely used in food industry to prevent the development of rancidity. The present study was focussed on investigating the antioxidant potential of Cucumis sativus seeds (CSS) and correlates these findings with mayonnaise enrichment and extends its shelf life. CSS exhibited the highest abundance in phenolic compounds (93.5 ± 0.1 mgGAE g^?1), flavonoids (57.4 ± 0.1 mgQE g^?1), β‐carotene (19.46 ± 0.4 mg carotenoids per 100 g) and high free radical scavenging activity. CSS (200 ppm) and butylated hydroxyanisole (200 ppm) were incorporated in mayonnaise and the oxidative stability was evaluated by peroxide, p‐anisidine and TBARS values during storage at different temperatures. Organoleptic evaluations indicated that CSS enriched sample was recorded the highest overall acceptability. The results from our study will provide scientific basis for CSS as natural preservative against lipid oxidation or food enrichment while developing functional foods.     

A study on the effect of bulk water content and drying temperature on the colour of dyed cotton fabrics

In the present study, the effect of various levels of bulk and free water content and its distribution on the colour of cotton fabrics dyed with direct dyes and their combinations were analysed. Twill and plain structures with two different parameters of fabric construction were chosen. The dyed samples were adjusted to different levels of wet pick‐up, with water ranging from 50% to 125% on the bone dry weight of the fabric (odwf) to achieve various levels of bulk water content. Further, the residual moisture content of the samples was adjusted to 40–10% odwf by means of hot air drying at different temperatures to obtain different levels of free water content and its distribution. For the assessment of colour and its comparison, the parameters ΣK/S and values were used. In order to bring out the true effect of moisture distribution and fabric structure, normalisation of dye uptake in the fabric based on weight and area were considered, respectively. The plain structures show a higher increase in colour than the twill structures when the bulk water content increases. At the same time, the fabric structures do not play a significant role, with increase in colour attributable to change in drying temperature. The findings reveal that the bulk water content, drying temperature and fabric geometry affects the colour of the fabric significantly.     

Raman,photoluminescence analysis on Cu(InAl)Se2 thin films and the fabrication of Cu(InAl)Se2 based thin film solar cells

Cu(InAl)Se₂ (CIAS) thin films have been prepared by chemical bath deposition technique. Thickness of the prepared films has been measured by gravimetric technique. The structure, composition and optical transition as well as bandgap have been estimated by X-ray diffraction, energy dispersive X-ray analysis and spectrophotometer analysis. Raman analysis has been made on the prepared CIAS thin films to assign the fundamental lattice mode and to confirm the films crystallinity and stoichiometry. PL analysis has been carried out to find the effective mass of holes and electron, dielectric constant, the involved defects and their activation energy. Cu(InAl)Se₂-based solar cells with different types of buffer layers such as CdS, CdS:Cu, CdS:In were fabricated. The current and voltage were measured using an optical power meter and an electrometer and the fabricated solar cells were illuminated using 100 mW/cm² white light under AM1 conditions.     

Low-Rank Coal Drying Technologies—Current Status and New Developments

Despite their vast reserves, low-rank coals are considered undesirable because their high moisture content entails high transportation costs, potential safety hazards in transportation and storage, and the low thermal efficiency obtained in combustion of such coals. Their high moisture content, greater tendency to combust spontaneously, high degree of weathering, and the dusting characteristics restrict widespread use of such coals. The price of coal sold to utilities depends upon the heating value of the coal. Thus, removal of moisture from low-rank coals (LRC) is an important operation. Furthermore, LRC can be used cost effectively for pyrolysis, gasification, and liquefaction processes. This article provides an overview the diverse processes—both those that utilize conventional drying technologies and those that is not yet commercialized and hence in need of R&D. Relative merits and limitations of the various technologies and the current state of their development are presented. Drying characteristics of low-rank coal as well as factors affecting drying characteristics of coal samples are also discussed.