Multi-material systems

There is also growing interest in multi-phase systems in which hard phase materials are dispersed in softer polyether diols. Such hard phase materials include polyureas, rigid polyurethanes and urea melamine formaldehyde condensates. Some of these materials yield high-resilience foams with load deflection characteristics claimed to be more satisfactory for cushioning as well as in some cases improving heat resistance and flame retardancy. 

New ways to recycle complex multi-material packaging systems. 

In a multi-reactant system where no identification of an unstable product was possible, one of the reactants had to be selected as primary reactant to prepare and index the main entry, with the other material(s) as secondary reactant(s). No strictly logical basis of choice for this is obvious. 

The past two decades have produced a revival of interest in the synthesis of polyanhydrides for biomedical applications. These materials offer a unique combination of properties that includes hydrolytically labile backbone, hydrophobic bulk, and very flexible chemistry that can be combined with other functional groups to develop polymers with novel physical and chemical properties. This combination of properties leads to erosion kinetics that is primarily surface eroding and offers the potential to stabilize macromolecular drugs and extend release profiles from days to years. The microstructural characteristics and inhomogeneities of multi-component systems offer an additional dimension of drug release kinetics that can be exploited to tailor drug release profiles. 

The main areas of application for more generalised models have, until recently, been restricted to binary and ternary systems or limited to ideal industrial materials where only major elements were included. The key to general application of CALPHAD methods in multi-component systems is the development of sound, validated thermodynamic databases which can be accessed by the computing software and, until recently, there has been a dearth of such databases. 

In this paper, a few examples of Raney catalysts produced by metastable processes and their catalytic properties are discussed. Then, some examples of multi alloy systems, their microstructures and general properties will be shown. Finally, we will discuss the possibility of forming large particle materials with high specific surface area. 

The most frequently applied analytical methods used for characterizing bulk and layered systems (wafers and layers for microelectronics see the example in the schematic on the right-hand side) are summarized in Figure 9.4. Besides mass spectrometric techniques there are a multitude of alternative powerful analytical techniques for characterizing such multi-layered systems. The analytical methods used for determining trace and ultratrace elements in, for example, high purity materials for microelectronic applications include AAS (atomic absorption spectrometry), XRF (X-ray fluorescence analysis), ICP-OES (optical emission spectroscopy with inductively coupled plasma), NAA (neutron activation analysis) and others. For the characterization of layered systems or for the determination of surface contamination, XPS (X-ray photon electron spectroscopy), SEM-EDX (secondary electron microscopy combined with energy disperse X-ray analysis) and... 

Of all the analytical techniques inorganic mass spectrometry has occupied a favoured place for the characterization of initial materials including such multi-layered systems due to its specific properties, such as high sensitivity, low detection limit, high dynamic range and the capability to determine isotope ratios. 

The potential storage of the mass spectrometer output in digital form has made possible the matching of mass fractograms against computer file stored reference data and hence the rapid identification of the material so that multi-component systems, after prior separation by GC or LC techniques, can be analyzed within the time frame required for the thruput of the sample... 

Multi-scale modelling of composite material systems (ISBN-13 978-1-85573-936-9 ISBN-10 1-85573-936-4)... 

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