Synthesis and Characterisation of Aminoplast Microcapsules for Controlled Release of Bioactives. Influence of the Resin:Oil Ratio

In this study a series of melamine-formaldehyde (MF) microcapsules containing Melaleuca alternifolia oil as natural biocide with different polymer to oil ratio was prepared by the in situ polymerization (O/W) method. The characterization of the microcapsules properties was undertaken by different experimental techniques in order to establish a correlation between the polymer to oil ratio and the oil encapsulation efficiency and properties for further applications. The average size distribution was determined by Laser Diffraction Scattering (DLS) and the chemical structure by Fourier Transformed Infrared Spectroscopy (FTIR). The morphology was characterized by Scanning Electron Microscopy (SEM). Finally, the thermal stability of microcapsules and the permeability of the shell to the diffusion of the core material were analyzed by Thermogravimetric Analysis (TGA). The obtained results showed that the resin:oil ratio was critical in the microcapsule formation and properties. For lower values than the critical one there was no microcapsule formation. For values over the critical resin:oil ratio value microcapsules were formed with spherical morphologies of varying wall thickness and oil encapsulation.The research was partially supported by the Spanish Ministry of Economy and Competitiveness (MINECO) through the project IPT2012-1299-300000

Sustainable Reactive Polyurethane Hot Melt Adhesives Based on Vegetable Polyols for Footwear Industry

The aim of this work is to develop sustainable reactive polyurethane hot melt adhesives (HMPUR) for footwear applications based on biobased polyols as renewable resources, where ma-croglycol mixtures of polyadipate of 1,4-butanediol, polypropylene and different biobased polyols were employed and further reacted with 4-4′-diphenylmethane diisocyanate. The different reactive polyurethane hot melt adhesives obtained were characterized with different experimental techniques, such as Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), softening temperature and melting viscosity. Finally, their adhesion properties were measured from T-peel tests on leather/HMPUR adhesives/SBR rubber joints in order to establish the viability of the used biobased polyols and the amount of these polyols that could be added to reactive polyurethane hot melt adhesives satisfactorily to meet the quality requirements of footwear joints. All biobased polyols and percentages added to the polyurethane adhesive formulations successfully met the quality requirements of footwear, being comparable to traditional adhesives currently used in footwear joints in terms of final strength. Therefore, these new sustainable polyurethane adhesives can be considered as suitable and sustainable alternatives to the adhesives commonly used in footwear joints