A comparison of thermal degradation kinetic mechanisms between elongational and shearing flow fields for nano-silica/IFR synergistic fire retardant polypropylene nanocomposites

In this work, the same formulations of Nano-Silica/intumescent fire retardant polypropylene nanocomposites were prepared via a novel vane extruder and a tri-screw extruder, which represented elongational flow field and shearing flow field, respectively. Not only the synergistic combustion mechanisms of Kissinger method and Flynn-Wall-Ozawa method were revealed, but also the combustion effect and efficiency were compared. Both two methods proved specimens that processed by TE exhibited higher thermal stability. The smaller aggregates of physical initial Nano-Silica, the better dispersivity of aggregates in specimens that processed by VE. Such property broke the compactness degree of char layer.

The Influence of Bubbles on Foamed Cement Viscosity Using an Extended Stokesian Dynamics Approach

We want to study the influence of bubbles on the viscosity of suspensions with a computational approach that also accounts for the arrangement of the bubbles due to shearing flow. This requires a large number of bubbles to properly simulate and requires a large amount of computational resources. Here we develop a set of equations to define the viscosity ratio from the simulation results to show the influence of the bubbles on the viscosity as a function of the volume fraction. One application of this work has been used to study a specific type of cement that has bubbles injected into the slurry while it is still fluid. The bubbles are added to reduce the density but they also improve the properties of the cement with the increase in viscosity. We show that the computed results match the few experimental results that have been reported.