Papers by Keyword: Dynamic Rheometry

Abstract: The effect of several types of nanoparticles on the rheological properties of polycarbonate (PC) was compared. Four polycarbonate nanocomposites containing 5 wt% of layered silica (SiO₂), Iron oxide (Fe₃O₄), Iron oxide (α-Fe₂O₃), cupric oxide (CuO) nanoparticles were prepared via melt compounding at 260 °C. Compression molded samples were prepared and the dynamic rheological properties of the nanocomposites were investigated. The incorporation of the nanoparticles increased the storage modulus and consequently decreased the damping factor. In the Cole-Cole plot, PC filled layered silica and Fe₂O₃ nanoparticles showed more semi-circle pattern comparing to that of other nanocomposites implied more compatibility between PC and layered silica and also Fe₂O₃ nanofillers. While other nanocomposites showed more deviation from this pattern. Rotational mode in rheological studies showed that at low shear rate the viscosities of nanocomposites are higher than that of pure Polycarbonate. While at higher shear rate the viscosity of filled samples tend to approach the viscosity of pure PC.

Abstract: A newly developed resonator in combination with a UDS 200 rheometer allows performing different kinds of measurements. The characteristics of the resonator are its resonant frequency slightly above conventional rheometers, the high sensitivity allowing measurement of fluids with viscosities as low as that of water and the very small oscillation amplitudes. The nonlinear behavior of viscoelastic liquids can be analyzed using parallel superposition of shear. It is known that the parallel complex shear modulus differs from the complex modulus of a fluid at rest. First measurements have shown the ability of the instrument to quantify this effect. At the same time, normal force, shear rate viscosity and complex viscosity can be measured on a sample.