Composite materials matrix composites

Applied Sciences, Inc. has, in the past few years, used the fixed catalyst fiber to fabricate and analyze VGCF-reinforced composites which could be candidate materials for thermal management substrates in high density, high power electronic devices and space power system radiator fins and high performance applications such as plasma facing components in experimental nuclear fusion reactors. These composites include carbon/carbon (CC) composites, polymer matrix composites, and metal matrix composites (MMC). Measurements have been made of thermal conductivity, coefficient of thermal expansion (CTE), tensile strength, and tensile modulus. Representative results are described below. 

There are many ways to classify composites, including schemes based upon (1) materials combinations, such as metal-matrix, or glass-fiber-reinforced composites (2) bulk-form characteristics, such as laminar composites or matrix composites (3) distribution of constituents, such as continuous or discontinuous or (4) function, like structural or electrical composites. Scheme (2) is the most general, so we will utilize it here. We will see that other classification schemes will be useful in later sections of this chapter. 

Depending upon what type of host matrix material is used in creating the composite material, the composites may be classified into three classes (1) polymer-matrbe composites, (2) metal-matrix composites, and (3) ceramic-matrix composites. We discussed the characteristics of matrix materials earlier when we covered metals and plastics. 

Lignocellulosic polymer composites refer to the engineering materials in which polymers (procured from natural/petroleum resources) serve as the matrix while the lignocellulosic fibers act as the reinforcement to provide the desired characteristics in the resulting composite material. Polymer composites are primarily classified into two types (a) fiber-reinforced polymer composites and (b) particle-reinforced polymer composites. Figure 1.5 (a) shows the classification of polymer composites depending upon the type of reinforcement. 

L DUandro, AT DiBenedetto, J Groeger. The effect of fiber-matrix stress transfer on the strength of fiber-reinforced composite materials. Polymer Composites 9 209-221, 1988. 

Thermal properties of thermoplastic starch composites reinforced with pehuen husk showed the potential of this bioliber as an excellent reinforcement for composite materials. TPS composites showed a good interaction between the fibers and the plasticized starch matrix due to the natural affinity between husk and starch in the pehuen seed. TPS/PLA/PV A blend showed partial miscibility or co-continuous phase and TPS/PLA/PV A composites presented also discontinuities at the biofiber-polymeric matrix interface. The incorporation of biofiber improved the thermal stability of the composites, increasing the initial decomposition temperature. The biofiber hinders the out-dififusion of the volatile molecules (e.g., glycerol), retarding the decomposition process of starch composites. On the other hand, the degree of crystallinity of composites decreases when pehuen husk content increases (Castano et al. 2012). 

The preceding chapters demonstrated the possibilities of such approaches for refractory carbides, nitrides and their solid solutions, i.e., for systems that cover practically the entire set of compounds which are used in modern hard alloy composite materials matrix. 

The mechanical behavior of concrete should be viewed from the point of view of a composite material. A composite material is a three dimensional combination of at least two chemically and mechanically distinct materials with a definite interface separating the components. This multiphase material will have different properties from the original components. Concrete qualifies as such a multiphase material. Concrete is composed of hydrated cement paste (C-S-H, CH, aluminate, and ferrite-based compounds) and imhydrated cement, containing a network of a mixture of different materials. In dealing with cement paste behavior, basically it is considered that the paste consists of C-S-H and CH with a capillary system. The model of concrete is simplified by treating it as a matrix containing aggregate embedded in a matrix of cement paste. This model provides information on the mechanical properties of concrete. 

O Brien, T.K., Characterization of Delamination Onset and Growth in a Composite Laminate in Damage in Composite Materials, ASTM STP 775, p. 140-167,1982 Poursartip, A. Ashby, M. F., Beaumont P.W.R., The Fatigue Damage Mechanics of Fibrous Laminates in Proceedings of the European Workshop on Nondestructive Evaluation of Polymers and Polymer Matrix Composites, Polymer NDE (edited by Khg. Ashbee), Technomic Publishing, p. 250-260, 1984... 

One more application area is composite materials where one wants to investigate the 3D structure and/or reaction to external influences. Fig.3a shows a shadow image of a block of composite material. It consists of an epoxy matrix with glass fibers. The reconstructed cross-sections, shown in Fig.3b, clearly show the fiber displacement inside the matrix. The sample can be loaded in situ to investigate the reaction of matrix and fibers to external strain. Also absorption and transmission by liquids can be visualized directly in three-dimensions. This method has been applied to the study of oil absorption in plastic granules and water collection inside artificial plant grounds. 

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