Heat-Resistant Polymer Composites Based on Ethylene Tetrafluoroethylene Mixed with Inorganic Polyoxides.

This pilot study aimed at investigating an alternative to irradiation-crosslinking to increase the structural stability of ethylene tetrafluoroethylene (ETFE), by mixing this polymer matrix with polyoxides. The latter consisted of aluminum polyphosphate (AP) having a flow temperature near to that of ETFE to facilitate melt-mixing by extrusion, and rigid fillers of metakaolin (MK). It was found that the ETFE/AP/MK composite with the formulation 60/20/20 (wt %) exhibited the most relevant properties.

Flow Structure and Mixing Efficiency of Viscous Fluids in Microchannel with a Striped Superhydrophobic Wall.

The peculiarities of a Newtonian fluid flow structure in microchannels with a striped superhydrophobic lower wall texture are studied by means of numerical modeling. In the Cassie-Baxter state, an oblique orientation of such a texture induces helicoidal streamlines with micro spirals. Such a flow structure favors the enhancement of fluid mixing efficiency, which can be quantified using the total root-mean-square deviation of streamlines from the microchannel axis.

Apparent slip of shear thinning fluid in a microchannel with a superhydrophobic wall.

The peculiarities of simple shear flow of shear thinning fluids over a superhydrophobic wall consisting of a set of parallel gas-filled grooves and solid stripes (domains with slip and stick boundary conditions) are studied numerically. The Carreau-Yasuda model is used to provide further insight into the problem of the slip behavior of non-Newtonian fluids having a decreasing viscosity with a shear rate increase. This feature is demonstrated to cause a nonlinear velocity profile leading to the apparent slip.

Steady-state deformation behavior of confined composite droplets under shear flow.

The shear-induced dynamics of two-dimensional composite droplets in a narrow channel is investigated numerically. The droplets consist of a viscous inner droplet (core) and shell immersed in a continuous Newtonian fluid. Attention is focused on studying the effects of confinement at different core-to-shell radii ratios, relative viscosities of the medium components, and interfacial tensions on the steady-state deformation and orientation of a composite droplet.