Population balance modelling for a flow induced phase inversion based granulation in a two-dimensional rotating agglomerator

A novel two-dimensional rotating agglomerator was developed to carry out the flow induced phase inversion (FIPI) based granulation. The process in this agglomerator shows that a continuous paste flow (mixed with liquid binder and primary particles) is extruded into the interstice of two relatively rotating disks, as the paste becomes solidified due to the loss of heat to the disks, it is then broken into granules by the shearing force imposed by the rotating disk. Experimental measurements have shown that the size of these granules is enlarged along the positive radial direction of the disks. It is also found that these granules contain approximately the same quantity of binder in terms of its volume fraction. The paper thus proposes a population balance (PB) model to describe the growth of the granules by considering a size independent agglomeration kernel. The PB simulated results are found to be well capable of describing the change of the particle size distribution (PSD) of the granules in the radial direction. This study also proposes a velocity profile for the paste flow and attempts to establish a quantitative relationship between the granulation rate and the deformation rate as this would help us understand the mechanism of the agglomeration. It is hoped that this study would be used to improve the design of the agglomerator and to assure the control of the process and the granular product quality

Melt Strength Behavior of Polyethylene Blends

Melt strength data are presented on different types of binary polyethylene blends as linear low density polyethylene/low density polyethylene (LLDPE/LDPE), linear low density polyethylene/high density polyethylene (LLDPE/HDPE) and LDPE/LDPE. Melt strength was assessed from uniaxial tensile experiments with a Rheotens apparatus. In addition, the blends were characterised in terms of a few other rheological properties such as the zero-shear viscosity and the extrudate swell in capillary extrusion. For the LLDPE/LDPE blend pairs synergistic effects were observed for the melt strength and some other properties. No melt strength synergism was observed for the LLDPE/HDPE and the LDPE/LDPE blends. The results are discussed in terms of the Bersted model on the effects of long chain branching on the low-shear melt viscosity of polyethylenes