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Mixing in RIM is made mainly by advective mechanisms, rather than diffusion. In this paper, the advective mechanisms that enable reducing the mixing scales down to the values required for the complete chemical reaction of the two monomers inside the RIM mixing chamber are identified and studied. From Computational Fluid Dynamics (CFD) simulations of non-diffusive two-phase flow using the Volume-of-Fluid (VOF) model, a linear scale of segregation is determined as a measure of the degree of mixing and the effect of the Reynolds number is studied.

Hybrid scaffolds composed of hydroxyapatite (HAp), in particular in its nanometric form (n-HAp), and chitosan (CS) are promising materials for non-load-bearing bone graft applications. The main constraints of their production concern the successful implementation of the final purification/neutralization and sterilization steps. Often, the used purification strategies can compromise scaffold structural features, and conventional sterilization techniques can result in material's thermal degradation and/or contamination with toxic residues. In this context, this work presents a process to produce n-HAp/CS scaffolds mimicking bone composition and structure, where an innovative single step based on supercritical CO extraction was used for both purification and sterilization. A removal of 80% of the residual acetic acid was obtained (T = 75°C, p = 8.0 MPa, 2 extraction cycles of 2 h) giving rise to scaffolds exhibiting adequate interconnected porous structure, fast swelling and storage modulus compatible with non-load-bearing applications. Moreover, the obtained scaffolds showed cytocompatibility and osteoconductivity without further need of disinfection/sterilization procedures. Among the main advantages, the proposed process comprises only three steps (n-HAp/CS dispersion preparation; freeze-drying; and supercritical CO extraction), and the supercritical CO extraction show clear advantages over currently used procedures based on neutralization steps. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 965-975, 2018.

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A mesostructured NETmix reactor was adapted to develop a continuous process to produce microcapsules, focusing on the steps commonly used in batch formulation: the emulsion and cure. Microcapsules were formed through a polycondensation process by coating Miglyol, a skin-hydrating emollient, with melamine-formaldehyde, which is a resistant shell material with surface smoothness. Different recirculation times were tested for the cure step. Microcapsules show a spherical shape and smooth membrane. Efficiencies of encapsulation of 75%, core contents of 70%, and diameters around 20 μm, ideal range for textile impregnation, were obtained. Scanning electron microscopy shows the integrity of microcapsules on textiles after impregnation and their flexible behavior. The thermogravimetric analysis confirmed the thermal stability of microcapsules up to 210°C. With the NETmix reactor, it is possible to reduce the cure time of traditional batch formulation in 80%, producing microcapsules with similar characteristics in a continuous process.