Composites short-fiber reinforced polymers

Fu, S. and Lauke, B Effects of fiber length and fiber orientation distributions on the tensile strength of short-fiber-reinforced polymers, Composites Sci. Technol., 56, 1179 (1996). 

Figure 5.97 Plot of composite tensile strength versus fiber volume fraction for an aligned, short fiber-reinforced polymer matrix composite. The dotted lines show the corresponding values for continuous fibers for comparison purposes. Reprinted, by permission, from N. G. McCrum, C. P. Buckley, and C. B. Bucknall, Principles of Polymer Engineering, 2nd ed., p. 281. Copyright 1997 by Oxford University Press.

A.2.4 Discontinuous-Fiber-Reinforced Polymer-Matrix Composites Sheet Molding Compound. Of the parameters influencing the mechanical properties in short-fiber-reinforced polymer-matrix composites, fiber composition, matrix composition, fiber geometry, and manufacturing method will be elaborated upon here. 

The incorporation of short fibers into polymers greatly affects their fracture behavior. Several modes of failure would occur in the short fiber reinforced polymer composites including fiber breakage, crack deflection, crack bridging, fiber pullout and matrix deforraa-... 

Fu, S.Y., Hu, X., Yue, C.Y., 1999. The flexural modulus of misaligned short-fiber-reinforced polymers. Composites Science and Technology 59, 1533—1542. 

Calundann GW (1979) Polyester of 6-hydroxy-2-naphthoic acid and para-hydroxy benzoic acid capable of readily undergoing melt processing. US Patent 4,161,470, 17 July 1979 Chang L, Friedrich K (2010) Enhancement effect of nanoparticles on the sliding wear of short fiber-reinforced polymer composites a critical discussion of wear mechanisms. Tribol Int 43 2355-2364... 

Fu, S. Y., and Mai, Y.W., Thermal Conductivity of Misaligned Short-Fiber-Reinforced Polymer Composites , Journal of Applied Polymer Science, 88, 1497-1505, 2003. 

The above equations correspond to the intuitive understanding that in the former case, the mechanical response of the laminar composite is essentially dominated by the performance of the fibers, thus giving the upper-boimd reinforcing effect, while in the latter case, the matrix (and the fibers-to-matrix adhesion) is playing the key role and dictates the lower-bound reinforcement. As we will see, some micro-mechanical models for short fibers composites clearly emphasize such upper and lower limits, and it follows that what can really be achieved when manufacturing a short fiber-reinforced polymer object is indeed between those two extremes. 

Short fiber reinforcement of TPEs has recently opened up a new era in the field of polymer technology. Vajrasthira et al. [22] studied the fiber-matrix interactions in short aramid fiber-reinforced thermoplastic polyurethane (TPU) composites. Campbell and Goettler [23] reported the reinforcement of TPE matrix by Santoweb fibers, whereas Akhtar et al. [24] reported the reinforcement of a TPE matrix by short silk fiber. The reinforcement of thermoplastic co-polyester and TPU by short aramid fiber was reported by Watson and Prances [25]. Roy and coworkers [26-28] studied the rheological, hysteresis, mechanical, and dynamic mechanical behavior of short carbon fiber-filled styrene-isoprene-styrene (SIS) block copolymers and TPEs derived from NR and high-density polyethylene (HOPE) blends. 

Though short fiber-reinforced mbber composites find application in hose, belt, tires, and automotives [57,98,133,164] recent attention has been focused on the suitability of such composites in high-performance applications. One of the most important recent applications of short fiber-mbber composite is as thermal insulators where the material will protect the metallic casing by undergoing a process called ablation, which is described in a broad sense as the sacrificial removal of material to protect stmcrnres subjected to high rates of heat transfer [190]. Fiber-reinforced polymer composites are potential ablative materials because of their high specific heat, low thermal conductivity, and ability of the fiber to retain the char formed during ablation [191-194]. 

Ramsteiner, F. and Theysohn, R The influence of fiber diameter on the tensile behavior of short-glass fiber reinforced polymers, Composites Sci. Technol., 24, 231-240 (1985). 

Termonia, Y Structure-property relationships in short-fiber-reinforced composites,./. Polym. Sci., Polym. Phys. Ed., 32, 969 (1994). 

Friedrich, K. and Karger-Kocsis, J. (1989). Unfilled and short fiber reinforced semi-crystalline thermoplastics. In Fractography and Failure Mechanisms of Polymers and Composites, (A.C. Roulin-Moloney ed.), Elsevier Appl. Science, London, pp. 437-494. 

Chen, F. and Jones, F. R., Injection moulding of glass fibre reinforced phenolic composites 1. Study of the critical fibre length and the interfacial shear strengtli, Plast., Rubber Composites Proc. Appl, 23, 241 (1995). Termonia, Y., Structure-property relationships in short-fiber-reinforced composites, J. Polym. Set, Polym. Phys. Ed., 32, 969 (1994). 

Eulaliopsis binata fiber-reinforced polymer composites are more eco-friendly and cost effective compared to the traditional synthetic fiber-reinforced composites. The aim of the present work was to study the reinforcing potential of the Euiaiiopsis binata fibers in the short fiber form. The mechanical performance of these Euiaiiopsis binata fiber polymer composites was found to be higher than that of the pure polymer. However challenges still exist In further improving the mechanical properties of these composites to make them competitive to their synthetic counterparts. 

As previously discussed, fibers that form in situ should reduce the viscosity of the composite during processing conditions, if compared to short fiber reinforced thermoplastic. Moreover, it will be shown that the viscosity of the LCP and thermoplastic polymer will be resonably lower than the viscosity of the enginnering thermoplastic by itself, accordingly with the viscosity of deformable particles in viscous fluid. 

The properties of thermoplastic composites containing fibers as fillers are dependent on a number of parameters, which include the properties of the matrix material, the size and aspect ratio of the fibers, dispersion of the fibers and the interface. In development of these composites, two important issues need to be addressed, namely, the incompatibility between the natural fibers and polymer matrix, and the tendency of the fibers to form aggregates [67]. Additionally, the composites exhibit poor dimensional stability due to moisture absorption. The orientation of the fibers is also important. In short-fiber reinforced composites, the orientation of the fibers is usually random and therefore the properties of such composites are not as superior as those containing continuous fibers. Optimization of processing conditions and use of coupling agents/compatibilizers and treatment of fibers can enhance the properties of these composites. 

A.A. Bakar, and N. Baharulrazi, Mechanical properties of benzoylated oil pahn empty fruit bunch short fiber reinforced poly(vinyl chloride) composites. Polym. Plast. Technol. Eng. 47, 1072-1079 (2008). 

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