AMINO SURFACE FUNCTIONALIZED MICROCAPSULES AS CURING AGENTS FOR POLYURETHANE FOAMS

摘要

This work regards the development of microcapsules (MCs), containing glycerol in their core, with the goal of being sustainable solid curing agents for one-component polyurethane (PU) foams. Indeed, they should be able to burst and release their content only at the spraying stage, in order to promote an accelerated curing of the PU foam. It has been found that the surface treatment, using an amino silane, of the previously developed (inorganic) silica MCs, led to the best performance as curing agents for PU one component foam (OCF). In fact, the amino functionalized MCs exhibited a more perfect spherical shape, were less aggregated, did not exhibit significant leaching and led to a significant increase in the curing rate of the PU foam. The amino groups were found to react with the isocyanate groups present in the PU pre-polymer, forming a thin layer of polyurea on the surface of the MCs, which prevents any leaching of encapsulated glycerol inside the aerosol can containing the PU pre-polymer and, therefore, allows a long shelf life of the product, required for commercial application. The study involved characterization techniques, such as Scanning Electron Microscopy, Fourier Transformed Infrared Spectroscopy, Thermal Gravimetric Analyses, leaching and curing speed evaluation.