RESUMEN
An effective dispersant, oleyl phosphate (OP), for the dispersion of poly(urea-formaldehyde)-based microcapsules in a typical epoxy coating material is proposed. Based on electron microscopy observations and rheological and mechanical characterizations, it is observed that the addition of merely 0.5 wt % of OP is sufficient to obtain good dispersion of the microcapsules in the epoxy. In the self-healing and anticorrosion experiments, a microcapsule content of at least 15 wt % is required to efficiently restore the epoxy matrix and provide corrosion protection to underlying low-carbon steel when the particles are not dispersed; however, the amount of microcapsules required to obtain good self-healing and anticorrosion efficiencies can be greatly reduced to only 5 wt % when the microcapsules are dispersed by OP.
RESUMEN
Gelatin-hydroxyapatite composite microspheres composed of 21% gelatin (G) and 79% hydroxyapatite (HA) with uniform morphology and controllable size were synthesized from a mixed solution of Ca(NO3)2, NH4H2PO4 and gelatin by a wet-chemical method. Material analyses such as X-ray diffraction (XRD), scanning/transmission electron microscopy examination (SEM/TEM) and inductively coupled plasma-mass spectroscopy (ICP-MS) were used to characterize G-HA microspheres by analyzing their crystalline phase, microstructure, morphology and composition. HA crystals precipitate along G fibers to form nano-rods with diameters of 6-10nm and tangle into porous microspheres after blending. The cell culture indicates that G-HA composite microspheres without any toxicity could enhance the proliferation and differentiation of osteoblast-like cells. In a rat calvarial defect model, G-HA bioactive scaffolds were compared with fibrin glue (F) and Osteoset® Bone Graft Substitute (OS) for their capacity of regenerating bone. Four weeks post-implantation, new bone, mineralization, and expanded blood vessel area were found in G-HA scaffolds, indicating greater osteoconductivity and bioactivity than F and OS.