Effect of structural characteristics on impact breakage of agglomerates

The mechanical properties and evolved structure of agglomerates depend strongly on the manufacturing method. There is a great interest in finding a simple way of establishing a rank order in their processing behaviour, e.g., the ease with which they could be dispersed in fluids. For this reason, the breakage propensity of two types of detergent agglomerates produced by different processes but with the same formulation has been evaluated under different conditions by impact testing with a view to diagnose differences in mechanical properties and structure arising from their manufacturing method. The effects of impact velocity, agglomerate size, impact angle, fatigue, humidity, and temperature have been analysed. Both samples show extensive plastic deformation due to the elongation and eventual rupture of the interparticle bridges, especially for the humidified samples. Reducing the temperature increases the extent of breakage substantially. The impact test results of samples kept at - 20 degreesC show brittle failure mode, whilst those of oblique impacts at 45degrees and ambient conditions show a semi-brittle failure mode by shear deformation. Drying strengthens the agglomerates presumably due to the solidification of bridges. In contrast, humidifying the granules decreases their strength. A general comparison of the impact test results of both samples for different feed sizes shows that, due to the structural differences, the breakage trend of these two types of agglomerate varies with increasing agglomerate size. (C) 2002 Elsevier Science B.V All rights reserved.