Recent Advances in Boron Nitride Based Hybrid Polymer Nanocomposites

Boron nitride (BN) is an eminent inorganic compound having many interesting characteristics such as improved oxidation resistance, mechanical strength, good thermal conductivity (TC), higher bandgap, high chemical stability, thermal stability, high hydrophobicity, and electrical insulation. The use of BN as a filler in polymers is a well-established strategy to tailor the properties of polymer composites. Recent studies depict an interesting urge to reap the synergistic effect of various nanofillers with BN in the form of hybrids. Hence the consolidation of the works on BN based hybrid fillers would definitely attract researchers so that these new filler systems could be transformed into useful polymer nanocomposites in future. This review article focuses on the synthesis and characterization of various boron nitride based hybrids in detail. Moreover, the review also throws light on different BN hybrid reinforced polymer nanocomposites (PNCs) and their thermal, electrical, electronic as well as biomedical applications in a detailed manner. Thus the review anticipates serving as a tool toward understanding the recent trends in the field of boron nitride hybrid based ternary polymer composites.     

Effect of Pasteurization and Retort Processing on Spectral Characteristics,Morphological, Thermal,Physico‐Mechanical,Barrier and Optical Properties of Nylon‐Based Food Packaging Materials

The effect of pasteurization and retort processing on spectral, morphological, thermal, physico‐mechanical, barrier and optical properties of three different packaging materials viz., PP/N6/PP, PET/N6/cPP and SiO_x‐PET/N6/cPP were studied. These packaging materials were packed with distilled water, which acted as a food simulant. Subsequently, these pouches were subjected to different thermal processing conditions such as pasteurization and retort processing. Both the processing techniques found to have retained the mechanical properties of all packaging materials. Water vapour transmission rate (WVTR) and oxygen transmission rate (OTR) of nylon‐based combinations were increased after processing. Gloss found to decrease invariably irrespective of the material and increases with the severity of the treatment. XRD diffractogram shows changes in crystal structure as a result of thermal processing, and SEM analysis shows the crystal fragmentation. Absorption of water by the amide group of nylon 6 was observed, which could be a reason for the increase in OTR and WVTR. Copyright © 2014 John Wiley & Sons, Ltd.     

Hemp seed oil: Minor components and oil quality

Owing to its high content of omega‐6/omega‐3 fatty acids and bioactive minor components with antioxidant activities, hemp seed oil is now recognized for its health benefits by a large number of consumers. This paper primarily discusses the profile of minor components in hemp seed oil and their beneficial and adverse effects on oil quality. While tocopherols, polyphenols and phytosterols prevent oxidative deterioration of hemp seed oil, the high amount of chlorophyll can be detrimental to oil quality.     

Evaluation of kinetics and transport mechanism of solvents through natural rubber composites containing organically modified gadolinium oxide

The solvent transport properties of the prepared composites were analysed using solvents of varying cohesive energy density and the effect of both modified as well as unmodified filler on the sorption and diffusion behaviour of NR vulcanisates has been investigated. It is found that the equilibrium uptake decreases with increase in filler content, as anticipated owing to the restrictions offered by the filler for solvents to diffuse into the polymer matrix. The mechanism of transport in natural rubber composites was carefully tracked and it was found to exhibit an anomalous mode of solvent transport where the polymer relaxation is in par with the rate of diffusion. Theoretical modelling of the swelling parameters was done and the results were found to be in agreement with existing models. The excellent swelling resistance coupled with the simultaneous improvement in mechanical properties would definitely pave way for the utilisation of these composites as barrier membranes.     

Growth features of ammonium hydrogen<Emphasis Type="Italic">d</Emphasis>-tartrate single crystals

Ammonium hydrogend-tartrate (d-AHT) single crystals were grown in silica gel. The growth features of these crystals with variation of parameters like specific gravity of the gel, gel pH, acid concentrations, concentration of the feed solution and gel age were studied in detail.     

Role of solvent interaction parameters in tailoring the properties of chlorobutyl rubber nanocomposites

Chlorobutyl rubber, a special class of butyl rubber, which exhibits superior air impermeability, is the elastomer of choice for the inner tubes and liners of tires. Chlorobutyl rubber nanocomposites containing layered silicates were prepared using solvents with varying cohesive energy density and the effect of solvent–clay and solvent–rubber parameters in determining the properties of the nanocomposites were studied. The nanocomposites so prepared were characterized by X‐ray diffraction, scanning electron microscopy and transmission electron microscopy. The results were interpreted with the help of thermodynamic concepts and a correlation between the mechanical properties of the nanocomposites and the difference in the interaction parameters was done. The same correlation was then applied to gas barrier properties and trends identical to mechanical properties were observed. Thereby it was shown that a strong relationship exists between properties of a system and solubility parameters in solution mixing process. POLYM. COMPOS., 37:353–359, 2016. © 2014 Society of Plastics Engineers     

MIXED CONVECTION INDUCED BY MEMS-BASED THERMAL SHEAR STRESS SENSORS

The effect of buoyancy caused by heat generation from a microelectromechanical system (MEMS)-based thermal shear stress sensor is investigated. Due to the small size and relatively low power consumption of such sensors, the buoyancy effect on the overall flow structure is generally negligible. However, its impact on the flow variables such as shear stresses can be significant because such quantities are local and depend on the gradients of the velocity profile next to the sensor. Due to the small dimension of the MEMS sensor, a multiscale modeling approach is adopted to examine the effect of buoyancy on the velocity and wall shear stress profiles. Full-length channel computations are initially performed with finer resolution near the sensor region. Using the boundary conditions derived from the full-length computations, another simulation is performed concentrating on a small region near the shear stress sensor. Based on the temperature distribution in the region of the sensor, the effective thermal length scale is several times the streamwise dimension of the sensor. For a state-of-the-art MEMS sensor dimension of 200,mu {bf m} , the effect of buoyancy on the accuracy of shear stress measurement can be noticeable.     

Effect of lysine incorporation,annealing and heat moisture treatment alone and in combination on the physico-chemical,retrogradation, rheological properties and in vitro digestibility of kithul (Caryota urens L.) starch

Physico-chemical, retrogradation, rheological properties and in vitro digestibility of lysine incorporated kithul starch modified by annealing, heat moisture treatment and its combinations were studied. LS-AHMT (annealed-heat moisture treated lysine incorporated kithul starch) exhibited lowest amylose leaching. LS-AHMT showed significantly (P ≤ 0.05) higher relative crystallinity. LS-ANS (annealed lysine incorporated kithul starch), LS-HMT (heat moisture treated lysine incorporated kithul starch) and LS-AHMT formed more weak gel by the effect of annealing, heat moisture treatment and its combination. LS-AHMT showed lowest pasting viscosities, G′ and G″ values among the modified kithul starch, which indicates its lower retrogradation properties. In vitro digestibility of kithul starch decreased after modifications and LS-ANS, LS-HMT and LS-AHMT showed significantly higher resistant starch content. The current study showed that annealing, heat moisture treatment and its combination on NS-LS (lysine incorporated kithul starch) effectively modified kithul starch properties.     

Highly active and stereospecific polymerizations of 1,3-butadiene by using bis(benzimidazolyl)amine ligands derived Co(II) complexes in combination with ethylaluminum sesquichloride

A family of cobalt(II) complexes supported on tridentate dibenzimidazolyl ligands having a general formula: [N(CH₃)(CH₂)₂(Bm-R)₂]CoCl₂ (where Bm = benzimidazolyl, R = H; -Me; -Bz), have been prepared by the condensation of o-phenylene diamine with methyliminodiacetic acid. The Co(II) complexes exhibited high activities for the polymerization of 1,3-butadiene, on activation with ethylaluminum sesquichloride (EASC), to yield predominantly cis-1,4 microstructure. The polymers are characterized by high molecular weight with polydispersity values between 2.35 and 3.37. The ligand modification shows remarkable influence on polymerization activity. The stereospecificity of the catalysts is consistent for a wide range of reaction conditions, except temperature. The electronic influence of ligand structure towards metal center is investigated by using cyclic voltammetric analysis and the generation of cationic active centers is identified via UV-vis spectroscopic analysis of the catalyst system.     

Value addition to spent osmotic sugar solution (SOS) by enzymatic conversion to fructooligosaccharides (FOS), a low calorie prebiotic

Value addition of spent osmotic sugar solution (SOS) obtained after the osmotic dehydration of carrot cubes using 60 °Bx sucrose solution has been studied. Two sets of experiments, one with the use of fresh carrots in every cycle of osmotic dehydration (3 h) and in the other set, carrots of previous cycle were reused in successive cycles, were carried out. The SOS obtained in each cycle was concentrated to 60 °Bx and used in successive cycles. FOS was produced from SOS (with or without concentration) by transfructosylation reaction of fructosyl transferase enzyme produced by Aspergillus oryzae MTCC 5154 under submerged fermentation condition. An FOS yield of 50.63 ± 0.94 to 57.86 ± 0.18% was obtained in both cases, which is comparable with the literature reports. FOS produced from SOS gets enriched with leached out bioactive components of fruits and vegetables used. The β-carotene concentration was in the range of 1300.9 ± 25.1 to 2800 ± 68.3 µg/100 ml of FOS. The colour of the FOS produced was golden brown and was much more appealing than FOS produced from sucrose.Industrial relevanceThe implementation of osmotic treatment of fruits and vegetables using concentrated sugar solution presents a critical factor due to the management of spent osmotic solutions. Disposal of spent osmotic solution has severe economical, environmental and technological implications. The possibilities of reuse of SOS have been suggested. The present investigation offers a better alternative for the use of SOS for developing a technologically viable process for the production of FOS. The resulting FOS is a highly valued low calorie, non-cariogenic prebiotic with high market demand in neutraceutical food sector.