Abstract Summary (Max 250 words)
Highly filled polyurethane (PU) formulations are widely used across industrial applications, yet their processing remains complex and difficult to scale. As a matter of fact, translating these materials from laboratory development to industrial-scale manufacturing remains challenging due to their complex rheology, high solids loading, elevated viscosity, and sensitivity to processing conditions. The scientific literature highlights that both powder blending and high viscosity blending suffer from the difficulty of even characterizing the material of interest, making fully predictive design and scale-up especially problematic [1]. In this study, we investigate how filler wetting dynamics, agglomerate breakup mechanisms, air entrainment and release behavior, and variations in impeller geometries collectively influence dispersion quality and processing time. Our findings demonstrate that no single traditional scale up criterion, such as constant tip speed, constant shear rate, or constant power per unit volume, adequately captures the behavior of the highly filled dispersions across different formulations. Instead, robust and transferable scale up requires an integrated framework that considers parameters such as filler type and concentration, impeller design, shaft positioning, and the evolving rheological profile throughout the mixing process. [1] Handbook of Industrial Mixing, intro, xliii
