Matrix fiber

In investigations of the failure of fiber compositions (PETP — short glass fibers) [251] it was found that the main process responsible for composite failure under load is the rupture at the matrix-fiber interface. The author of [251] observed formation of microvoids in loaded samples, both at the interphases and in the bulk. The microvoids, or cavities) grow in size and become interconnected by microcracks, and this results in fiber separation from the binder. However, when the matrix-fiber bond is strong enough, the cavities appear mostly in the bulk of matrix, the failure of the specimen does not over-power cohesion and traces of polymer remain on the fibers. 

Proper reinforcement of rubber matrix using hllers can be achieved only if there exists adequate adhesion between the hller and the mbber. Rubber-mbber adhesion and rubber-hller adhesion both without and with adhesion promoters have been studied extensively [125-127]. Fiber-matrix adhesion in short fiber-rubber composites is always a field of extensive research. If the fibers are not bonded properly with the rubber matrix, fibers will shde past each other under tension deforming the matrix, thereby reducing the strength properties. In the case of short fiber-reinforced rubber composites, loads are not directly applied to the fibers, but are apphed to the matrix. To obtain a high-performance composite, the load must be effectively transferred to the fibers, which is possible only when the fiber-matrix interphase is sufficiently strong. In addition, the adhesion between the fiber and the matrix should be such that the failure occurs in the matrix rather than at the interphase [92]. 

Ceramic-matrix fiber composites, 26 775 Ceramics mechanical properties, 5 613-638 cyclic fatigue, 5 633-634 elastic behavior, 5 613-615 fracture analysis, 5 634-635 fracture toughness, 5 619-623 hardness, 5 626-628 impact and erosion, 5 630 plasticity, 5 623-626 strength, 5 615-619 subcritical crack growth, 5 628—630 thermal stress and thermal shock, 5 632-633... 

Marshall, D.B. (1984). An indentation method for measuring matrix-fiber frictional stresses in ceramic composites. J. Am. Ceram. Soc. 67. C259-260. 

Lhotellier, F.C. and Brinson, H.F. (1988). Matrix fiber stress transfer in composite materials Elasto-plastic model with an interphase layer. Composite Structures 10, 281-301. 

As in the case with polymer-intense composites, the matrix and fiber must be matched for decent properties. Table 8.6 contains a listing of typical matrix-fiber mixes. 

Composite Applications The Role of Matrix, Fiber and Interface, T. L. Vigo and B. J. Kinzig, eds., VCH Publishing, New York, 1992. 

The interaction of two substrates, the bond strength of adhesives are frequently measured by the peel test [76]. The results can often be related to the reversible work of adhesion. Due to its physical nature such a measurement is impossible to carry out for particulate filled polymers. Even interfacial shear strength widely applied for the characterization of matrix/fiber adhesion cannot be used in particulate filled polymers. Interfacial adhesion of the components is usually deduced indirectly from the mechanical properties of composites with the help of models describing composition dependence. Such models must also take into account interfacial interactions. 

Finally, the matrix must be attached to the cell process and the canalicular wall in order for the drag force to be transmitted to the membrane and its underlying intracellular actin cytoskeleton. If such linker molecules are present, drag forces exerted on the matrix fibers will produce a tensile stress on these linker molecules that, in turn, will produce radial (hoop) strain in the intracellular actin cytoskeleton as schematically shown in Figure 6. Possible candidates for these attachment molecules are CD44, laminin, and various integrins. [64, 149],... 

Each process provides capabilities such as meeting production quantity (small to large quantities and/or shapes), performance requirements, proper ratio of reinforcement to matrix, fiber orientation, reliability/ quality control, surface finish, materials used, quantity, tolerance, time schedule, and so forth versus cost (equipment, labor, utilities, etc.). There are products when only one process can be used but there can be applications where different processes can be used. 

For most polymer matrix fiber composites, Eq. (15.38) gives a reasonable description of the tensile strength. 

Table 2 A combinatory approach to establish the matrix-fiber-process relationship...

Glass fibers are extensively used by industiy because of their reinforcing effect, and the improvements they produce in thermal properties such as a reduction in thermal expansion and an increase in heat deflection temperature. The most challenging tasks of fiber application include the incorporation process which must be designed to prevent breakage, improve matrix fiber adhesion, prevent fiber corrosion in some environments, and develop proper fiber orientation. 

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