a b s t r a c tCracking is observed when a UO 2 single crystal is oxidised in air. Previous studies led to the hypothesis that cracking occurs once a critical depth of U 3 O 7 oxidised layer is reached. We present some l-Laue Xray diffraction results, which evidence that the U 3 O 7 layer, grown by topotaxy on UO 2 , is made of domains with different crystalline orientations. This observation was used to perform a modelling of oxidation coupling chemical and mechanical parameters, which showed that the domain patterning induces stress localisation. This result is discussed in comparison with stress localisation observed in thin layer deposited on a substrate and used to propose an interpretation of UO 2 oxidation and cracking.

This article aims at preparing and characterizing efficiency of melt‐extruded polymer nanocomposites‐based drug delivery systems with tailored drug release properties. 5‐aminosalycylic acid (5‐ASA)‐loaded halloysite nanotubes (HNT)/plasticized starch nanocomposites were prepared and evaluated for the drug release, swelling characteristics, and degradability. The structure, morphology, and properties of the nanocomposites were characterized by using Fourier transform infrared spectroscopy, X‐ray diffraction, scanning electron microscopy, and UV‐visible spectrophotometry. The 5‐ASA and HNT hybrid formation is confirmed, as well as the presence of 5‐ASA within the HNTs and an excellent dispersion of the 5‐ASA/HNT hybrid in the thermoplastic starch matrix. The swelling of nanocomposites strongly depends on the temperature but not on pH. The degradability tests yield a stabilized weight loss of 24 wt%, which is ascribed to leaching of plasticizers. The presence of HNTs delays the drug release process. The observed in vitro drug release after 2 h is 37.2% for plasticized starch and 30.0% for the nanocomposites. Overall results indicate that the developed nanocomposite system can be a potential candidate for drug delivery applications. POLYM. ENG. SCI., 55:573–580, 2015. © 2014 Society of Plastics Engineers

Novel porous bionanocomposites based on halloysite nanotubes as nanofillers and plasticized starch as polymeric matrix were successfully prepared by melt-extrusion. Foaming was obtained by adding water as natural blowing agent, and by increasing the die temperature. Both the expansion ratio and the porosity increase with increasing die temperature. Addition of high water content allows reducing the foaming temperature. Moreover, the introduction of halloysite has double benefits: these fillers act both as a nucleating agent increasing the porosity and as a barrier agent increasing the proportion of small cells. Foams based on plasticized starch with a blend of glycerol and sorbitol loaded with 6 wt % of halloysite, extruded at 117 C, present the cellular structure and the mechanical properties required for scaffold applications.

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