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High performance polysulfone/γ-alumina biocom-patible nanocomposites are reported for the first time and the effects of γ-alumina surface modification are explored. We show that some fatty acids chemisorb over the surface of γ-alumina forming nanosized self-assembled structures. These structures present thermal transitions at high temperatures, 100 °C higher than the melting temperatures of the pure acids, and are further shifted about 50 °C in the presence of polysulfone. The chemistry involved in the chemisorption is mild and green meeting the stringent bio sanitary protocols for biocompatible devices. It has been found that the self-assembled structures increase mechanical strength by about 20% despite the foreseeable lack of strong particle−matrix interactions, which manifests as small variations in both the glass transition temperature and the Young's modulus. Electron microscopy observation of fractured surfaces has revealed that some acids induce an extended region of influence around the nanoparticles and this fact has been used to explain the enhancement of mechanical strength.

In this experimental work, injection molding of alumina using a binder system based on high‐density polyethylene and paraffin wax was performed to produce dental brackets. The use of a microinjection molding machine, permitting a careful control of the volume injected into the microcavity, allowed to produce dental brackets with complex shape and high aspect ratio. The organic component was removed by a combination of solvent and thermal debinding. After sintering at 1600°C, the final parts retained the green‐part shape, with high surface finish. The density achieved (99.8%) was higher than that for similar parts obtained by uniaxial compaction.

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