High energy dry coating mixing: Elements on velocities, temperatures and melting

Abstract

In dry coating processes no liquid, solvent, binder or water, is required. This makes them advantageous compared to wet coating alternative: being low cost, no drying step required, environmentally friendly (no volatile organic compounds related problems) and simple in operation. But there is still a lack of fundamental knowledge of the implied mechanisms. Often the process itself has been empirically designed and is not always well characterized. In this work, some hydrodynamic elements are developed in a high energy mixer used for dry coating: the specific behavior of the Nara hybridizer NHS-0 is investigated. In the first part, recirculation velocities and temperatures are derived during the process, or when the purge is on. The effects of the pressure purge and of the rotor velocity on the purge and the effect of the rotation on the temperature increase are studied. In the second part, a simple experimental approach is carried out to derive qualitatively the local temperature inside the apparatus with the help of polymers with different melting temperatures. This approach illustrates a first step for dry coating application with waxes.

Additive manufacturing of PA12 carbon nanotube composites with a novel laser polymer deposition process

“…A first approach is based on dispersing the CNTs and the powder by ultrasonic impact in a solvent and subsequent isolation of the mixture after solvent removal 31–33 . The second approach involves coating the dry particles through high energy mixing 34–37 . As the latter process is not in need of solvents and generates directly free flowing powders, it is economically more viable while achieving a homogenous distribution of CNTs on the surface of the polymer particle.…”