Composition-Structure-Property Relationships

Zhao JC (2006) Combinatorial approaches as effective tools in the study of phase diagrams and composition-structure-property relationships. Prog Mater Sci 51 557-631... 

Of course, the micromechanical relations (bounds, approximations or fit models) presented in this chapter for the effective elastic properties are by no means restricted to the alumina-zirconia system but can be applied to many types of ceramies and eeramie composites. On the other hand they cannot be expected to be automatically applicable to matrix-inclusion type composites in cases where the matrix consists of nonlinearly elastic materials (polymers), viscoelastic materials (glasses or porcelain at high temperature) or elastoplastic materials (metals). In particular, they cannot be a priori expected to be justified for materials of biological origin, although their application to many of these materials, e g. bone, might be seductive and dictated by practical needs. With respect to the inherent anisotropy and the hierarchical microstructure of these materials [Ontanon et al. 2000], however, any mathematical modeling or description of their composition-structure-property relationships has to be performed with due caution. 

Structure—Property Relationships The modem approach to the development of new elastomers is to satisfy specific appHcation requirements. AcryUc elastomers are very powerhil in this respect, because they can be tailor-made to meet certain performance requirements. Even though the stmcture—property studies are proprietary knowledge of each acryUc elastomer manufacturer, some significant information can be found in the Hterature (18,41). Figure 3a shows the predicted according to GCT, and the volume swell in reference duid, ASTM No. 3 oil (42), related to each monomer composition. Figure 3b shows thermal aging resistance of acryHc elastomers as a function of backbone monomer composition. 

Introduces the chemistry and structure—property relationships of a variety of new materials and composites... 

Recent developments in polymer chemistry have allowed for the synthesis of a remarkable range of well-defined block copolymers with a high degree of molecular, compositional, and structural homogeneity. These developments are mainly due to the improvement of known polymerization techniques and their combination. Parallel advancements in characterization methods have been critical for the identification of optimum conditions for the synthesis of such materials. The availability of these well-defined block copolymers will facilitate studies in many fields of polymer physics and will provide the opportunity to better explore structure-property relationships which are of fundamental importance for hi-tech applications, such as high temperature separation membranes, drug delivery systems, photonics, multifunctional sensors, nanoreactors, nanopatterning, memory devices etc. 

The nanometer- to micrometer-scale dimensions of supramolecular assemblies present many challenges to rigorous compositional and structural characterization. Development of adequate structure-property relationships for these complex hierarchical systems will require improved measurement methods and techniques. The following areas constitute critical thrusts in instrument development. 

Termonia, Y Structure-property relationships in short-fiber-reinforced composites,./. Polym. Sci., Polym. Phys. Ed., 32, 969 (1994). 

Boerio, F. J. and Gosselin, C. A.. "Structure-Property Relationships of Silane Films on Aluminum Substrates." 36th Annual Conference Reinforced Plastics/Composites Institute, SPI. February 16-20. 1981. Session 2-G. 

The combination of different monomeric units at various ratios generates totally new materials, in most cases with the expected properties and rarely with unexpected, superior properties. Therefore, the investigation of series of polymers in parallel has a great importance not only to elucidate structure-property relationships but also to be able to realize magic compositions. 

The general approach of graded radiation exposure can also be used to examine light driven processes such as photopolymerization [19]. For example, Lin-Gibson and coworkers used this library technique to examine structure-property relationships in photopolymerized dimethacrylate networks [38] and to screen the mechanical and biocompatibility performance of photopolymerized dental resins [39]. In another set of recent studies, Johnson and coworkers combined graded light exposure with temperature and composition gradients to map and model the photopolymerization kinetics of acrylates, thiolenes and a series of co-monomer systems [40 2]. 

It is important to mention that the structure/properties relationships which will be discussed in the following section are valid for many polymer classes and not only for one specific macromolecule. In addition, the properties of polymers are influenced by the morphology of the liquid or solid state. For example, they can be amorphous or crystalline and the crystalline shape can be varied. Multiphase compositions like block copolymers and polymer blends exhibit very often unusual meso- and nano-morphologies. But in contrast to the synthesis of a special chemical structure, the controlled modification of the morphology is mostly much more difficult and results and rules found with one polymer are often not transferable to a second polymer. 

Nearly all structure/properties relationships that were discussed for homopolymers are also valid for copolymers. Additional dependencies exist as a result of the composition and structure of the different types of copolymers. 

Relatively few processible polyimides, particularly at a reasonable cost and in reliable supply, are available commercially. Users of polyimides may have to produce intractable polyimides by themselves in situ according to methods discussed earlier, or synthesize polyimides of unique compositions in order to meet property requirements such as thermal and therm oxidative stabilities, mechanical and electrical properties, physical properties such as glass-transition temperature, crystalline melting temperature, density, solubility, optical properties, etc. It is, therefore, essential to thoroughly understand the structure—property relationships of polyimide systems, and excellent review articles are available (1—5,92). 

Since the macroscopic properties of a material are strongly dependent on its structure, studies of structure/property relationships are among the most important issues in material science. The properties of SiAlON ceramics are strongly influenced by their microstructure and chemical composition. 

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