Browsing by Subject "Creep"
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Item Open Access Evaluation of nusselt number for a flow in a microtube with second-order model including thermal creep(ASME, 2012-07) Çetin, BarbarosIn this paper, Nusselt number for a flow in a microtube is determined analytically with a constant wall heat flux thermal boundary condition. The flow assumed to be incompressible, laminar, hydrodynamically and thermally fully-developed. The thermo-physical properties of the fluid are assumed to be constant. The effect of rarefaction, viscous dissipation, axial conduction, which are important at the microscale, are included in the analysis. For the implementation of the rarefaction effect, two different second-order slip models are used for the slip-flow and temperature-jump boundary conditions together with the thermal creep at the wall. Closed form solutions for the fully-developed temperature profile and Nusselt number are derived as a function of Knudsen number, Brinkman number and Peclet number. Copyright © 2012 by ASME.Item Open Access Property enhancement in polypropylene ternary blend nanocomposites via a novel poly(ethylene oxide)-grafted polystyrene-block-poly(ethylene/butylene)-block-polystyrene toughener-compatibilizer system(John Wiley and Sons, 2018) Tekay, E.; Başkır, S.; Nugay, N.; Nugay, T.; Ortaç, Bülend; Şen, S.Synthesis and characterization of a novel toughener-compatibilizer for polypropylene (PP)-montmorillonite (MMT) nanocomposites were conducted to provide enhanced mechanical and thermal properties. Poly(ethylene oxide) (PEO) blocks were synthetically grafted onto maleic anhydride-grafted polystyrene-block-poly(ethylene/butylene)-block-polystyrene (SEBS-g-MA). Special attention was paid to emphasize the effect of PEO-grafted SEBS (SEBS-g-PEO) against SEBS-g-MA on morphology, static/dynamic mechanical properties and surface hydrophilicity of the resultant blends and nanocomposites. It was found that the silicate layers of neat MMT are well separated by PEO chains chemically bonded to nonpolar SEBS polymer without needing any organophilic modification of the clay as confirmed by X-ray diffraction and transmission electron microscopy analyses. From scanning electron microscopy analyses, elastomeric domains interacting with MMT layers via PEO sites were found to be distributed in the PP matrix with higher number and smaller sizes than the corresponding blend. As a benefit of PEO grafting, SEBS-g-PEO-containing nanocomposite exhibited not only higher toughness/impact strength but also increased creep recovery, as compared to corresponding SEBS-g-MA-containing nanocomposite and neat PP. The damping parameter of the same nanocomposite was also found to be high in a broad range of temperatures as another advantage of the SEBS-g-PEO toughener-compatibilizer. The water contact angles of the blends and nanocomposites were found to be lower than that of neat hydrophobic PP which is desirable for finishing processes such as dyeing and coating.