Acronitrile butadiene styrene/polycaprolactam/nano carbon black composites: Selective percolation,glass transition and temperature dependence of electrical conductivity

Preferential percolation is a promising strategy to develop conducting composites at lower loading of conducting filler; however, little information is available on temperature dependence of conductivity of such composites. This study reports synthesis and positive temperature coefficient (PTC) behavior of a novel multiphase polymer composite in which conducting filler preferentially percolates in a composite containing two incompatible polymers, both having glass transition in the temperature range of study. High electrical conductivity and good mechanical behavior was demonstrated by acrylonitrile butadiene styrene (ABS)/polycaprolactam (PCL)/nano carbon black (NCB) composites, which was dependent on blend composition as well as on the extent of NCB loading. PTC intensity was considerably less for ternary composites than it was for binary ABS/NCB or PCL/NCB composites. Theoretical analysis of the dispersion state of NCB in this phase separated system revealed preferential distribution of NCB at the interfacial region. PTC effect was also found to decrease significantly with increase in NCB content. ABS/PCL/NCB (1:1:2) composites showed no significant temperature dependence (zero positive coefficients) up to 413 K while ABS/NCB 30 wt% NCB composites showed highest PTC. A sudden rise was observed in the glass transition region of polymers for all composites; however, the effect was less pronounced for ternary composites. POLYM. COMPOS., 37:481–487, 2016. © 2014 Society of Plastics Engineers     

Chemical aspects of uranium recovery from seawater by amidoximated electron-beam-grafted polypropylene membranes

The amidoximated macroporous membranes (AO membranes) were prepared by post irradiation grafting of acrylonitrile (AN) onto thermally bonded non-woven matrix of poly(propylene) sheet using electron beams. These precursor membranes were reacted with hydroxylamine to convert AN to AO groups, and conditioned by treating them with 2.5% KOH at 80°C for 1 h. The water uptake capacity in seawater, Na⁺-exchange capacity, and uranium loading capacity from seawater of AO membranes were found to be 200±10 wt.%, (3.1±0.2)×10⁻⁴ mol/g, and (1.60±0.18)×10⁻³ mol/g, respectively. The expected functional group density based on the degree of AN grafting (125 wt.%) and its subsequent conversion to AO groups (80%) was found to be 7.8×10⁻³ mol/g. The comparison of the expected functional group density and uranium uptake capacity seems to suggest that UO₂²⁺ forms a complex with AO groups in 1:4 proportion. The uranium could be quantitatively desorbed (>90%) from the AO membrane in Na₂CO₃ and mineral acids like HCl in the equilibration times of 60 min and 40 min, respectively. Alkaline conditioning was found to be necessary for reuse of the membrane equilibrated with acid. However, AO membranes equilibrated with Na₂CO₃ could be reused without any conditioning for uranium sorption.     

An Intelligent Scheme for Slot Reservation in Vehicular Ad Hoc Networks

Vehicular ad hoc network is a solution for increasing road traffic demand.Non-safety messages are sent during the service channel interval.The slots during whic...     

Power couples: The synergy value of battery-generator hybrids

Battery hybrids—a battery system paired operationally with a generation system—can often provide more value than the individual systems alone. We identify and describe eight value streams that battery hybrids can provide. Additionally, we identify the trends of increasing renewable energy, demand for resilience, need for flexibility, and the increasing economics of hybrid systems of standalone diesel generation as supporting increased battery hybridization in the future.     

Physical,chemical, and biological investigations of composites for biomedical applications

In this article, the interplay between structural, electrical, and surface properties in determining the collective behavior of (hydroxyapatite, HAP) and (strontium titanate, ST) composites was reported. The monoliths HAP and ST were synthesized using sol-gel and solid-state reaction, respectively, and were mixed in different atomic concentrations (20, 40, 60, and 80 at.%) to prepare a series of composites. The prepared composites were then subjected to x-ray diffraction (XRD) and Raman analysis for probing the microstructural aspects. The analysis revealed no evidence of a phase that the reaction between the two monoliths might form. The crystallite sizes were in the range of 27.2–37.3 nm, and it increased with the content of ST in the composites. The Raman analysis revealed the presence of rutile that was later found to be the link in the display of bone-like apatite nucleation ability in the monolith ST and its composites. The FESEM analysis revealed that the grain sizes were 64–144 nm between the monoliths and were found to follow a similar trend to the crystallite size. The dielectric constant varied with temperature ranging from 5 to 35 (1 MHz) at 310 K for all the specimens. The dependence of on the grain size of the composites followed a nearly exponential relation. The bone-like apatite forming ability of the composites was studied by incubating the specimens in simulated body fluid (SBF). Additionally, the cytocompatibility (MG63 cell lines) and protein adsorption (bovine serum albumin [BSA]) of the selected specimens were also studied to comprehensively understand the delicate relationship between the electrical and biological properties. The protein adsorption was primarily related to the surface charge, and its dependence was found to be linear. Additionally, the of the composites was ≤35, which compliments the protein adsorption behavior of the specimens. The amount of adsorbed protein for all the specimens considered in this study was in the range of 3–32 μ g/ml. Furthermore, the specimens exhibited excellent cell viability of more than 90%. Based on the physical and biological investigations, 20H-80S was established as the best specimen that blends the characteristic feature of both the monoliths. Finally, the TEM and STEM mapping of the best specimen, projecting the suitability of 20H-80S in the design of electrically active scaffolds and possibly bioelectrets for biomedical applications, was also studied.     

Realization of floating triple crossing memristor emulator with dual inflection point static characteristics

Analog Integrated Circuits and Signal Processing - The incidence of multiple cross-over points on the v-i contour is an indication of multi-curvature nature of the static characteristics of the...