Studies into the effect of temperature on the impact of model particles in co-melt granulation

• Published in: Powder technology 2016-06, Vol.294, p.411-420
• Main Authors: Grau-Bove, J., Mangwandi, C., Walker, G., Ring, D., Cronin, K.
• Format: Article
• Language: English
• Subjects: Binder melting; Coefficient of restitution; Granulation; Impact
• ISSN: 0032-5910; 1873-328X
• DOI: 10.1016/j.powtec.2016.02.041

In co-melt granulation, collisions occur between the particles to be agglomerated and the binder material. Depending on the stage of granulation, the binder material can be in the solid or liquid phase. The outcome of these collisions controls the dynamics of the granulation process and the fundamental physics of the impacts are of interest. This paper examines the impact of glass beads (model particles) and solid Poly Ethylene Glycol (PEG) flakes on a substrate of PEG as the temperature of the PEG layer is increased from below its melting point to above it. While the layer is in the solid state, the result of the impact can be quantified by the coefficient of restitution. When the layer is in the liquid state, the impact can be quantified by the immersion behaviour. The results obtained show that the coefficient of restitution between either glass beads and PEG flakes and the PEG layer is strongly affected by temperatures. As the PEG layer approaches its melting point, the coefficient of restitution falls to zero. Once the temperature of the PEG layer exceeds the melting point, the impact is characterised by a transient maximum indentation and then rebound to an equilibrium position. These too are strongly dependent on temperature. The impact behaviour of a glass bead at the point of contact with a layer of polyethylene glycol that is maintained at temperatures either below or above its melting point (solidification temperature, TS). [Display omitted] •Impact behaviour of solid particles and a binder material is quantified.•For liquid binder, restitution coefficient is quantified by experiment and theory.•For solid binder, depth of penetration is quantified by experiment and theory.•Approach gives insight into mechanics of contact and granulation dynamics.