Glass fibers fiber strength aspects

As first described in Section 1.4.2, there are a number of ways of further classifying fiber-matrix composites, such as according to the fiber and matrix type—for example, glass-fiber-reinforced polymer composites (GFRP) or by fiber orientation. In this section, we utilize all of these combinations to describe the mechanical properties of some important fiber-reinforced composites. Again, not all possible combinations are covered, but the principles involved are applicable to most fiber-reinforced composites. We begin with some theoretical aspects of strength and modulus in composites. 

The effect of fiber diameter on the tensile strength of a glass-fiber-reinforced polystyrene composite is shown in Figure 5.100. Some reinforcements also have a distribution of fiber diameters that can affect properties. Recall from the previous section that the fiber aspect ratio (length/diameter) is an important parameter in some mechanical property correlations. 

Tensile Strength. Tensile strength data (Figure 7) indicate that the highest value was obtained with milled glass fiber (20% loading) and the relatively low value obtained with chopped integral strands. This may be related to the aspect ratio of dispersed milled fiber in the composite compared to chopped... 

In thermoplastics, the fillers and/or reinforcements can be in the form of particles, fibers or flakes. Fibers can be particularly effective since the flow patterns can create preferential orientation distributions and, therefore, directional properties. Table 10.36 shows typical properties of fibers, indicating the wide difference in strength and modulus compared to that of polymers. Glass fibers are typically 1-2 to 10-50 mm long, with an aspect ratio of 10-50. 

Fibers are used to enhance the strength and toughness of extruded ware. Refractory ceramic fibers (RCFs, e.g., asbestos, rock wool, glass fibers), though excellent tougheners, are being phased out, and hence, have become costly. Any material with aspect ratio would behave akin to fibers. Wollastonite and halloysite are examples of cheap, benign, natural materials. In... 

High aspect ratio fillers, such as woUastonite and glass fibers can have an even stronger effect than talc and mica on increasing the modulus of elasticity, tensile strength, and heat-distortion temperature of poly(lactic acid) (PLA)-based systems. 

Keywords long glass fiber, glass mat thermoplastic (GMT), shear lag model, rule of mixture, tensile modules, Cox-Krenchel model, aspect ratio, thermal properties, linear thermal expansion coefficient, lofting, tensile strength, Kelly-Tyson model, adhesion, wetting, glass mat, random fiber orientation. 

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