Resin matrices tensile strength

Sihcon carbide fibers exhibit high temperature stabiUty and, therefore, find use as reinforcements in certain metal matrix composites (24). SiUcon fibers have also been considered for use with high temperature polymeric matrices, such as phenoHc resins, capable of operating at temperatures up to 300°C. Sihcon carbide fibers can be made in a number of ways, for example, by vapor deposition on carbon fibers. The fibers manufactured in this way have large diameters (up to 150 P-m), and relatively high Young s modulus and tensile strength, typically as much as 430 GPa (6.2 x 10 psi) and 3.5 GPa (507,500 psi), respectively (24,34) (see Refractory fibers). 

A reinforced plastic sheet is to be made from a matrix with a tensile strength of 60 MN/m and continuous glass fibres with a modulus of 76 GN/m. If the resin ratio by volume is 70% and the modular ratio of the composite is 25, estimate the tensile strength and modulus of the composite. 

Polymer chemistry is important in obtaining adhesion to the glass surface (Figure 10). The tensile reinforcement factor—the ratio of tensile strengths of the reinforced system to the matrix resin—is used as a measure of adhesion. Two dissimilar polymers, polypropylene and nylon, are used to illustrate the importance of polymer chemistry. Polypropylene is an inherently difficult polymer to reinforce because of its nonpolar nature and lack of reactivity. Nylon, on the other hand, is highly polar and is one of the easiest thermoplastics to reinforce. The modified poly-... 

V/ = volume fraction of glass fiber lc = critical fiber length la = actual fiber length d = fiber diameter t = shear strength of matrix resin a = ratio of actual to critical fiber length composite tensile strength a/ = fiber tensile strength... 

Selection of a carrier resin is much more complex than one would naturally suspect. Some of the considerations seem obvious for instance one cannot use a carrier that is incompatible with the letdown resin. For example, low-density polyethylene (LDPE) is incompatible with ABS. It leads to delimitation in parts, poor impact, and low tensile strength. However, small amounts of LDPE are not a problem in ABS. It simply disappears in the matrix and has no measurable effect. Would the writer recommend using LDPE as a carrier for ABS concentrates Certainly not. However, pigments weighed in polyethylene bags are thrown bag and all into batch mixers with ABS everyday. The point is that questionable contaminants in polymers can be acceptable as long as the amounts are small and they are well distributed in the matrix. 

The materials tested were mainly unidirectional and bidirectional satin cloth laminate. Unsaturated polyester resin was used as a matrix. The tensile strength ratio of longitudinal fiber to transverse fiber was... 

Calculate (a) the modulus of elasticity, (b) the tensile strength, and (c) the fraction of the load carried by the fibers for a continuous glass fiber-reinforced epoxy resin, with 60% by volume E-glass fiber, stressed under isostrain conditions. The tensile strength and modulus of the fibers are 1800 MPa and 76 GPa, respectively, and the values of these quantities for the matrix are 60 MPa and 2.4 GPa, respectively. 

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