HNBR and its MWCNT reinforced nanocomposites : Crystalline morphology and electrical response

Morphology and electrical response of hydrogenated acrylonitrile butadiene rubber (HNBR) and its multiwall carbon nanotube (MWCNT) reinforced nanocomposites were studied by means of x-ray diffraction and broadband dielectric spectroscopy. HNBR systems were found to be semi-crystalline, with their crystallinity to increase with the addition of MWCNTs. In their dielectric spectra, four relaxation processes were detected. Ascending in relaxation time, these were attributed to: (i) interfacial polarization at the interface of crystalline and amorphous regions of HNBR and at the interface between HNBR and MWCNTs, (ii) glass to rubber transition of the amorphous part of HNBR, (iii) rearrangement of polar side groups, such as –CN, and (iv) local motions of small segments of the main elastomer chain. Electrical conductivity increases with MWCNT content and frequency increasing. The effect of temperature, on the electrical response, is more pronounced at low frequencies. The temperature dependence of the electrical conductivity strongly deviates from a pure Arrhenius behavior, signifying that the occurring conductance mechanisms do not correspond to a single thermally activated process. Relaxation dynamics imply that crystalline regions exert motion restrictions to large segments of the macromolecules in the amorphous phase and to polar parts of the systems

Molecular dynamics pre-simulations for nanoscale computational fluid dynamics

We present a procedure for using molecular dynamics (MD) simulations to provide essential fluid and interface properties for subsequent use in computational fluid dynamics (CFD) calculations of nanoscale fluid flows. The MD pre-simulations enable us to obtain an equation of state, constitutive relations, and boundary conditions for any given fluid/solid combination, in a form that can be conveniently implemented within an otherwise conventional Navier–Stokes solver. Our results demonstrate that these enhanced CFD simulations are then capable of providing good flow field results in a range of complex geometries at the nanoscale. Comparison for validation is with full-scale MD simulations here, but the computational cost of the enhanced CFD is negligible in comparison with the MD. Importantly, accurate predictions can be obtained in geometries that are more complex than the planar MD pre-simulation geometry that provides the nanoscale fluid properties. The robustness of the enhanced CFD is tested by application to water flow along a (15,15) carbon nanotube, and it is found that useful flow information can be obtained

Vacuum-Packaged Precooked Pork from Hogs Fed Supplemental Vitamin E: Chemical, Shelf-Life and Sensory Properties

Precooked longissimus chops and semimembranosus/adductor roasts from pigs (n = 30) given no supplemental vitamin E (CON) or supplemented with 100 mg vitamin E/kg diet (VITE) were evaluated for lipid oxidation, microbial growth, sensory characteristics, cooking/storage losses and reheating losses. Chops and roasts were vacuum packaged, precooked to 60°C and stored at 2°C for 0, 7, 14, 28, or 56 days. Lipid oxidation was lower in VITE chops and roasts than in CON chops and roasts. Off-flavor intensity scores were more acceptable and storage/ cooking losses were lower for VITE roasts than for CON roasts. Supplementation of vitamin E in a swine diet provided added protection against lipid oxidation and precooking pork under vacuum provided a palatable product with a shelf-life of 56 days