Surfactant screening techniques for effective dispersion of carbon black pigment

Effective dispersion of a pigment in a colour concentrate is imperative to its performance. A well dispersed pigment yields the true strength of a colour and becomes stabilised in the long run. To accomplish this, a suitable chemistry of the surfactant is a prerequisite for dispersion and stabilisation of the pigment. A plethora of surfactants are available commercially and it is very difficult to choose the right surfactant that suits the pigment chemistry. Carbon black, being difficult to disperse, was chosen in this study to provide dispersion from an effective surfactant. Simple screening processes, if available for these surfactants, can save a huge amount of time and energy compared with the conventional method of conducting individual experiments. This paper discusses the development of such simple surfactant screening techniques, which could make the selection process simpler and quicker.     

Falling ball method for determining zero shear and shear-dependent viscosity of polymeric systems: Solutions,melts, and composites

The falling ball method (FBM) is one of the well-established techniques for measuring the viscosity of Newtonian liquids at the room as well as at elevated temperatures and pressures. Owing to its simplicity and low cost, the possibility of extending its range of application to non-Newtonian systems including virgin and filled polymer melts, composites, polymer-solutions, and so forth, is explored here, In this work, theoretical results for the flow of power-law fluids past a sphere have been used to extract the values of the zero-shear viscosity and shear-dependent viscosity in the low-shear rate limit. The theoretical scheme outlined here has been validated by presenting comparisons with experimental results for scores of polymer solutions for which both falling sphere and rheological data are available in the literature. Indeed, the good correspondence obtained between these two independent data is encouraging and it is thus possible to use the FBM for shear-thinning systems when the resulting Reynolds numbers are such that the flow is viscosity-dominated, and the inertial effects are negligible. This implies that the Reynolds number should be ≤ ~1 for shear-thinning fluids and ≤ ~10⁻⁵ for shear-thickening fluids.     

Enhanced Analog Performance and High-Frequency Applications of Dielectric Engineered High-K Schottky Nanowire FET

Silicon - In this paper, Gallium Nitride (GaN) based Dielectric Engineered High-K GaN Schottky Nanowire Field Effect Transistor (DE-HK-GaN-SNWFET) is examined for enhancing analog performance for...     

Design and analysis of DDoS mitigating network architecture

International Journal of Information Security - Distributed Denial of Service (DDoS) attacks have emerged as the top security threat with the rise of e-commerce in recent years. Volumetric attacks...