Polyacrylamide and poly(acrylamide-co-2-acrylamido-2-methyl-1-propanesulfonic acid)-silica composite nanogels through in situ microemulsion polymerisation

Nanosize monodisperse composite particles of polyacrylamide (PAM) and poly(acrylamide-co-2-acrylamido-2-methyl-1-propanesulfonic acid)-silica [Poly(AM-co-AMPSA)-SiO₂] were prepared by water-in-oil in situ microemulsion polymerisation without surface treatment of silica. The synthesised composite particles were produced with controllable sizes ranging from 44 to 77 nm in diameter. Presence of silica filler in the nanoreactors facilitates the formation of well-defined discrete particles. The prepared nanocomposites were characterised by dynamic light scattering, transmission electron microscope, Fourier transform infrared spectrophotometer, thermogravimetric analyzer, differential scanning calorimeter, scanning electron microscope and X-ray diffraction. The spectroscopic result shows strong interactions of silica nanoparticles with sulphonic groups of 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPSA). The onset degradation temperature is increased from 227 to 262 °C in copolymer–silica composite as compared to polyacrylamide–silica (PAM–SiO₂) which indicates improved thermal stability. The shifting of glass transition temperature from 194 to 203 °C in copolymeric composite nanogels further confirms the existence of strong interactions of silica filler with poly(acrylamide-co-2-acrylamido-2-methyl-1-propanesulfonic acid) [Poly(AM-co-AMPSA)] chains. Also the chemical composition of polymeric chains and the affinity of polymer chains and silica influenced the morphology of nanogels.     

The Influence of Carbonaceous Material on the Melting Behaviour of Mould Powder

The melting behaviour of mould powder during continuous casting is an important consideration with respect to caster performance, production rate and steel quality. In this experimental study the effect of different carbonaceous materials on the melting characteristics of mould powders was evaluated. Using X‐ray diffraction, different types of carbon were quantitatively characterized in terms of their internal structure and reactivity experiments were conducted to investigate potential relationships between the structural morphology of carbons and their reactivity. High temperature microscopy and drip test experiments were then used to investigate the melting behaviour of mould powders containing different carbonaceous materials. From the results obtained, correlations were established between the structural factors, chemical reactivity and melting behaviour.     

Electron beam processing of LDPE/EVA/PCR ternary blends: radiation sensitivity evaluation and physico-mechanical characterization

LDPE/EVA/PCR blends having fixed percentage of PCR were prepared by melt mixing and irradiated to different radiation doses using electron beam. Gel fraction and crosslinking density of the blends were found to increase with increase in EVA content in the formulation, suggesting higher radiation sensitivity of EVA. The heat of mixing and polymer-polymer interaction parameter indicated better miscibility between EVA/PCR than between LDPE/PCR and LDPE/EVA. Dynamic mechanical properties of the blends were found to significantly vary with the variation in the EVA fraction in the blends. In the composition range studied the storage modulus decreased from 3.8 × 10⁸ to ∼1 × 10⁸ Pa at strain amplitude of 5 × 10⁻⁶ m. The experimentally obtained data deviated significantly from both the series as well as parallel model. The bulk density showed a positive deviation from additive rule. The X-ray diffraction pattern of the blends revealed reduction in the crystallinity of LDPE on blend formation. DSC thermograms of blends did not indicate any significant shift in the melting peaks, indicating immiscibility of LDPE and EVA domains in the presence of PCR.     

Prevention of metallic corrosion by lauric hydrazide and its salts under vapor phase conditions

Six organic volatile corrosion inhibitors (VCI) were synthesized using lauric hydrazide with various acids such as cinnamic acid, succinic acid, nitrobenzoic acid, phthalic acid, and maleic acid and evaluated as corrosion inhibitors of mild steel, copper, brass, zinc, and aluminum by weight loss and potentiodynamic polarization methods. All the investigated VCI exhibited good inhibition efficiency for all the metals tested. The inhibition efficiency of all compounds increased as the inhibitor concentration increased. Lauric hydrazide cinnamate showed the best results among all compounds studied. In addition, all inhibitors showed anodic behavior. Adsorption studies demonstrated that all the investigated compounds followed Temkin's adsorption isotherm.     

Edible mushrooms’ enrichment in food and feed: A mini review

Dietary fibres and high fibre-containing foods have been a huge attraction among researchers and nutraceutical industries due to their health-promoting benefits. From Greek and Roman times, edible mushrooms are considered the ‘elixir of life’ and are often stated as a new source of dietary fibre. Containing rich sources of essential amino acids and polysaccharides, mushrooms are viewed as an advantage over protein sources of both animal and plant origin. Additionally, the ability of mushrooms to grow under controlled conditions and attain high yield in a short span has made this added-value food of extreme interest. Nowadays, mushrooms and their by-products have been used to fortify various food products as well as for use in animal feed owing to their bioactive, therapeutic and nutritional value. Hence, this review intends to highlight the current knowledge on edible mushrooms and their waste for food and feed enrichment and nutritional purposes, along with their role in human and animal diet.     

A study toward the physicochemical properties of graft copolymer (partially carboxymethylated guar gum‐g‐N,N′‐dimethylacrylamide): Synthesis and characterization

Unreported graft copolymer of N,N′‐dimethylacrylamide (DMA) with partially carboxymethylated guar gum (CmgOH) has been synthesized and the reaction conditions have been optimized for affording maximum grafting using a potassium peroxymonosulphate (PMS)/thiourea (TU) redox initiators under nitrogen atmosphere. The study of graft copolymerization has been performed to observe maximum value of grafting parameters except percentage of homopolymer by varying the concentrations of DMA, PMS, and TU. The grafting parameters increase continuously on increasing the concentration of DMA from 8 × 10^?2 to 24 × 10^?2 mol dm^?3, PMS from 5 × 10^?3 to 21 × 10^?3 mol dm^?3, and TU from 1.6 × 10^?3 to 4.8 × 10^?3 mol dm^?3. The optimum temperature and time for grafting of DMA onto CmgOH were found to be 35°C and 120 min, respectively. The water‐swelling capacity of graft copolymer is investigated. Flocculation property for both coking and noncoking coals is studied for the treatment of coal mine waste water. The graft copolymer is characterized by Fourier transform infrared spectroscopy and thermogravimetric analysis. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010