Microstructure and Thermal Properties

Pourahmady, N., Bak, P.I. and Kinsey, R.A. (1992) Microstructure and thermal properties of ethylene-vinyl chloride copolymers. Journal of Macromolecular Science-Pure and Applied Chemistry 29,959-974. 

Table 2. Microstructure and thermal properties of linear PGCL polymerized at 170 C for 20 h, [M]/[Sn-oct] = 7,500/1 ...

Table 3. Microstructure and thermal property of star-shaped PGCL copolymers prepared at...

Moskal G, Swad zba L, Hetma nczyk M, Witala B, Mendala B, Mendala J, Sosnowy P. Characterization of microstructure and thermal properties of Gd2Zr207-type thermal barrier coating. Journal of the European Ceramic Society 2012 32 2025-2034. 

As can be seen from this figure, the heat-resistance was remarkably improved by the drastic changes in the microstructure from amorphous to polycrystalline structure. Another type of SiC-based fiber, SA fiber (2), has a sintered SiC polycrystalline structure and includes very small amounts of aluminum. This fiber exhibits outstanding high temperature strength, coupled with much improved thermal conductivity and thermal stability compared with the Nicalon and Hi-Nicalon fibers. The fabrication cost of the SA fiber is also reduced to near half of that of the Hi-Nicalon Type S [ 17]. The SA fiber makes SiC/SiC composites even more attractive to the many applications [18]. In the next section, the production process, microstructure and physical properties of the SA fiber are explained in detail. 

G.M. Benedikt, B.L. Goodall, N.S. Marchant, and L.F. Rhodes, Polymerization of multicyclic monomers using zirconocene catalysts. Effect of polymer microstructure on thermal properties, New ). Chem., 18 (1) 105—114,1994. 

A.H. Deutchman and R.J. Partyka (Beam Alloy Corporation observe, "Characterization and classification of thin diamond films depend both on advanced surface-analysis techniques capable of analyzing elemental composition and microstructure (morphology and crystallinity), and on measurement of macroscopic mechanical, electrical, optical and thermal properties. Because diamond films are very thin (I to 2 micrometers or less) and grain and crystal sizes are very small, scanning electron microscopy... 

As with other ceramic composites, the combination of a- and/or P-sialon with reinforcement agents results in sialon composites. This simple and obvious statement encompasses many factors which must be taken into account for successfully fabricating composites with a designed microstructure and improved properties (Prewo, 1989). For sialon matrix composites, the most important factors are physical compatibility including Young s modulus, elastic strain (Kerans and Parthasarathy, 1991) and thermal expansion coefficient (Sambell etal., 1972a, b), and chemical compatibility between sialon matrix... 

A consequence of the complex interplay of the dielectric and thermal properties with the imposed microwave field is that both Maxwell s equations and the Fourier heat equation are mathematically nonlinear (i.e., they are in general nonlinear partial differential equations). Although analytical solutions have been proposed under particular assumptions, most often microwave heating is modeled numerically via methods such as finite difference time domain (FDTD) techniques. Both the analytical and the numerical solutions presume that the numerical values of the dielectric constants and the thermal conductivity are known over the temperature, microstructural, and chemical composition range of interest, but it is rare in practice to have such complete databases on the pertinent material properties. 

Figure 1.1 showed the links between the formulation, the process and the texture. The first step is to understand how the formulation and process affect the microstructure. This requires microscopy techniques to visualize the ice crystals, air bubbles, fat droplets and matrix and image analysis to quantify their sizes, shapes and locations. The next step is to measure the mechanical, rheological and thermal properties and to relate them to the microstructure. The final stage is to relate these physical measurements to the sensory properties. This chapter describes the techniques used to make these measurements. 

CaP synthesis methods and their technological parameters can significantly impact stoichiometry of the synthesis product, its grade of crystallization, particle size, bioceramic phase composition, thermal stability, microstructure and mechanical properties. The important technologic parameters that impact properties of calcium phosphate synthesis product and then also of bioceramic, are temperature of synthesis, pH of synthesis environment, reagent type and concentration, as well as selection of raw materials, their purity and quality. All of the above mentioned also brings a significant impact on the tissue response of these bioceramic implants. 

N. P. Bansal, Effects of Thermal Ageing in air on Microstructure and Mechanical Properties of Hi-Nicalon Fiber-Reinforced Celsian Composites, unpublished work. 

Predicting fiber orientation. Isotropic constitutive models are not valid for injection-molded fiber-reinforced composites. Unless the embedded fibers are randomly oriented, they introduce anisotropy in the thermomechanical properties of the material. The fiber orientation distribution is induced by kinematics of the flow during filling and, to a lesser extent, packing. An extensive literature deals with flow-induced fiber orientation while much other work has been devoted to micromechanical models which estimate anisotropic elastic and thermal properties of the fiber-matrix system from the properties of the constituent fiber and matrix materials based on given microstructures. Comprehensive reviews of both research areas have been given in two recent books edited, respectively, by Advani and by Papathanasiou and Guell where many references can be foimd. 

Table 1 summarizes some microstructural and electrochemical properties of porous Si anode materials, as pertaining to the second approach mentioned above, collected from the literature published since 2005. Several synthesis methods have been identified for preparing the porous Si anode materials (column 1, Table 1). One of the two most adopted methods is known as the metal-assisted chemical etching (MACE denoted as E in Table 1). The fundamental principle of this method can be found in the handbook chapter Porous Silicon Formation by Metal Nanoparticle Assisted Etching. Figure 2 shows an example of the MACE-derived porous Si particle. The other most adopted method is magnesiothermic reduction (denoted as M in Table 1). In this method (see handbook chapter Porous Silicon Formation by Porous Silica Reduction ), porous Si oxide materials are reduced by magnesium vapor under high-temperature thermal treatment. The porous Si oxide precursors may be synthesized via the conventional sol-gel processes. Porous Si particles with unique pore structures, such as hollow interior and ordered mesoporosity, may be obtained from Si oxides having the same pore structures which are achieved by using proper templates.

Chou, L. H., and Wang, H. W., On the microstructural, optical, and thermal properties of hydrogenated amorphous carbon films prepared by plasma enhanced chemical vapor deposition, J. Appl. Phys., 74, 4673-4680 (1993). 

Dencheva N, Denchev Z, Oliveira M J and Funari S S (2010) Microstructure studies of in situ composites based on polyethylene/polyamide 12 blends, Macromolecules 43 4715-4726. Polaskova M, Cermak R, Sedlacek T, Kalus J, Obadal M and Saha P (2010) Extrusion of polyethylene/poljTDropylene blends with microfibrillar-phase morphology, Polym Compos S1 1427-1433. Wang H, Guo J and He Y X (2011) Rheology and thermal properties of polypropylene/poly(phenyl-ene sulfide) microfibrillar composites, Adv Mater Res 194-196 1506-1509. 

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