The physical and chemical properties of a new class of lithium conducting polymer electrolytes formed by dispersing ceramic powders at the nanoscale particle size into a poly(ethylenoxide) (PEO)-lithium salt, LiX complexes, are reported and discussed. These true solid-state PEO-LiX nanocomposite polymer electrolytes have in the 30-80 °C range an excellent mechanical stability (due to the network of the ceramic fillers into the polymer bulk) and high ionic conductivity (promoted by the high surface area of the dispersed fillers). These important and unique properties are accompanied by a wide electrochemical stability and by a good compatibility with the lithium electrode (assured by the absence of any liquids and by the interfacial stabilizing action of the dispersed filler), all this making these nanocomposite electrolytes of definite interest for the development of advanced rechargeable lithium batteries.
The aim of the present work was to study the possibility of building a porous scaffold for tissue engineering with a new bottom-up approach, obtained by assembling two-dimensional-micro, one-dimensional-nano sized poly(L-lactide) lamellar single crystals. This choice was dictated by the fact that polymer single crystals have structural and morphological features which can be exploited for chemical surface modifications to give a system characterized by a high specific active surface area. Indeed, the outermost amorphous regions can undergo functionalization reactions easily, whereas the inner, relatively inaccessible and inert crystalline core ensures morphological and mechanical stability. The assembling method employed to give the porous structures is based on a mould pressing, salt leaching technique and was found to be facile and versatile. In the first part of this paper we report the experimental results obtained to find the best conditions to achieve a suitable frame in terms of morphology, porosity and mechanical properties. In the second part of the paper, we describe the biological tests performed by using mouse fibroblasts seeded onto scaffolds prepared from pristine and surface hydrolysed lamellae. The results show that the samples obtained are suitable for sustaining cells which can proliferate and reach the inner pores of the scaffold containing hydrolysed single crystals much better than those prepared from pristine lamellae. Copyright (c) 2012 Society of Chemical Industr
In this study, we examined the thermal de-composition of polyhydroxyalkanoates (PHAs) such as the homopolymer poly(3-hydroxybutyrate) and the copolymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate). They are biodegradable polymers that can replace plastics produced from nonrenewable resources, such as polypropylene. The biopolymers we analyzed were commercial PHAs [obtained by means of pure cultures, with hydroxyvalerate (HV) contents of 0 and 10.4 mol %] and biopolymers produced in our laboratories (by means of an enriched activated sludge at two different organic loads, 8.5 and 20 gCOD/L, with a HV content of 20 mol %). To process these biopolymers, it is important to know their thermal stability. For this reason, thermal degradation in air by means of dynamic thermogravimetry (TG) was carried out. The TG data were adjusted to the nth-order general analytical equation to evaluate the best order of the reaction, the temperatures of the onset and end of thermal decomposition, and the kinetic parameters. The latter were also calculated by means of other integral and differential methods and compared to those obtained by the general analytical solution. Finally, the influence of the preparation method (pure and mixed cultures and HV content within the biopolymer) on thermal stability was analyzed
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