Use of shear sensitive coloured guest component to track powder mixing in adhesive binary mixtures

The mixing performance in binary powder blends with components exhibiting guest and host type interactions was assessed by tracking the colour change of the mixture. The operation parameters like mixing time and speed were studied in compositions containing lactose monohydrate as host and iron oxide nanoparticle as coloured guest components. The mixing characteristics were analysed through visual imaging and colorimetric estimations. Furthermore, surface analytical techniques like scanning electron microscope (SEM) for surface area coverage (SAC) determination and Finite Dilution Inverse Gas chromatography (FD-IGC) for surface energy heterogeneity characterisation were employed. The mixing sensitivity of the coloured tracer and the consequent colour transitions under different conditions helped in validating the mixing performance and operation conditions. The FD-IGC results showed a lowering of the energetic heterogeneity for better quality mixtures. Thus, a shear sensitive coloured nano-tracer can be utilised for a simple, quick and cost-effective estimation of the mixture quality and for the validation of mixing process.