Fiber-Matrix Interaction

The residual strength and impact behavior of the fiber/matrix on carbon fiber reinforced metal laminates has been studied [130,131]. 

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The variational energy principles of classical elasticity theory are used in Section 3.3.2 to determine upper and lower bounds on lamina moduli. However, that approach generally leads to bounds that might not be sufficiently close for practical use. In Section 3.3.3, all the principles of elasticity theory are invoked to determine the lamina moduli. Because of the resulting complexity of the problem, many advanced analytical techniques and numerical solution procedures are necessary to obtain solutions. However, the assumptions made in such analyses regarding the interaction between the fibers and the matrix are not entirely realistic. An interesting approach to more realistic fiber-matrix interaction, the contiguity approach, is examined in Section 3.3.4. The widely used Halpin-Tsai equations are displayed and discussed in Section 3.3.5. 

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. 

Narkis, M., Chen, E. J. H. and Pipes, R. B., Review of methods for characterization of interfacial fiber-matrix interactions, Polym. Composites, 9, 245 (1988). 

Ha, J.S., Chawla, K.K. and Engdahl, R.E. (1993). Effect of processing and fiber coating on fiber-matrix interaction in mullite fiber-mullile matrix composites. Mater. Sci. Eng. A 161, 303-308. 

All of the silane treatments in this study diminish the physisorptive capacity of glass fiber substrates, as shown by the isotherms (Fig. 2) and the desorption volumes of physically adsorbed water (Table 4, peak 1). This is one reason for their efficacy at promoting wet strength retention and enhancing other composite properties that degrade when moisture adsorbs at the fiber-matrix interface. Chemisorptive properties for probe adsorbates that are imparted to the substrate by silane deposition may also influence fiber-matrix interaction. 

The method adopted for the comparison of silane treatment effects on fiber-matrix bond strength was the determination of interfacial shear strength (IFSS) in single-filament composite (SFC) specimens [13, 14], which we have used extensively in investigating fiber-matrix interactions. The conditions of silane treatment of single fibers as well as the corresponding effects on IFSS could thus be carefully controlled, measured, and compared. 

The exact role of matrix microstructure in determining the physical properties of C-C composites is difficult to determine precisely because the microstructural variations and fiber-matrix interactions are highly complex. Some insight into the importance of... 

After pyrolysis, the carbon body is further densified by liquid pitch, resin impregnation, or CVD. Studies were undertaken to understand the role of the matrix, pores, and cracks, and fiber-matrix interactions in this material as it is stressed. The intent was to determine whether processing differences could alter the fracture behavior and possibly improve the physical characteristics ... 

Fig. 6.16 Definition of damage at the macroscale, mesoscale, and microscale of a composite damage is considered at three different length scales. The microscale is concerned only with the fiber-matrix interaction, The mesoscale concerns the interaction of fibers and matrix with cracks or other defects. The macroscopic properties are independent of any microstructural length dimension. When going from a finer scale to a coarser scale, the description of the finer scale is made through average quantities.

The literature in the domain has indeed shown improvements in performanee relating to the addition of this type of fibers. This evolution is conneeted to a strengthening of the matrix, becanse of exeellent fiber-matrix interactions. This results in ... 

L.R. Betterman et al. Fiber Matrix Interaction in Microfiher Reinforced Mortar, Elsevier Science hic., Newyork, (1995), pp. 128-138... 

It is the properties of this interphase that affect the mechanics of fiber-matrix interaction. In turn, the global performance of the composite ma-... 

M. Schmiicker, B. Kanka, H. Schneider, Temperature-induced fiber/matrix interactions in porous alumino silicate ceramic matrix composites, 7. Europ. Ceram. Soc. 20 2491-2497 (2000). 

Improvements in the properties and performance of fiber-reinforced polymer matrix materials from the addition of nano- and microscale particles have been reported in the literature [8], The availabiHty of different types of nanoparticles offered the possibiHty to tailor fiber/matrix interactions at a nanoscale level. Recently, it has been proven that nanoparticles homogeneously dispersed in a polymer matrix are able to play a beneficial role on the fiber/matrix interfacial adhesion in different types of structural composites [ 11 ], as it will be shown later. Hence, regarding structural properties, nanocomposites appear particularly appropriate as means of enhancing the mechanical properties of conventional composites rather than their use as nanocomposites by themselves, except in some particular cases. 

Denault J, Vukhanh T, Crystallization and fiber matrix interaction during the molding of PEEK carbon composites. Polymer Composites, 13(5), 361-371, 1992. 

Kowbel W, Shan CH, The mechanism of fiber-matrix interactions in carbon-carbon composites. Carbon, 28, 287, 1990. 

M. Narkis, E.J.H. Chen, R.B. Pipes, "Review of methods for characterization of interfacial fiber-matrix interactions". Polymer Composites 9 (4), 245-251 (1988). Proceedings of the first International Conference on Interfacial Phenomena in Composite Materials - IPCM 89 , Sheffield (UK), September 5-7,1989. Controlled Interphases in Composite Materials , (Proceedings of the third International Conference on Composite Interfaces, Cleveland (Ohio, USA), May 21-24, 1990), Ed. by H. Ishida, Elsevier (N.Y., Amsterdam, London), 1990. Composite Science and Technology, 42 (1-3), 1991. 

It was shown that higher fiber-matrix interaction in the composites prepared using coupling agents prohibit the crystallinity enhancement caused by the fiber... 

In this chapter, some results will be presented, focusing attention on the properties in terms of physical and chemical structure of the coconut and sugarcane bagasse fibers, processing behavior and final thermal properties of these fibers with thermoplastics or thermosetting matrices, paying particular attention to the use of physical and chemical treatments for the improvement of fiber-matrix interaction. 

Effect of fiber treatments The rate of water uptake by OPF-PF composites upon different fiber treatments was in the order extracted (highest) > non-extracted > propionylated > acetylated (lowest) [73]. The variation between the lowest and highest was 30%. It is also observed that most of the fiber treatments increased water absorption of the composites except alkali treatment, however the treatments reduced water absop-tion of the fibers [45]. Alkali treatment removes the amorphous waxy cuticle layer of the fiber and activates hydroxyl groups leading to chemical interaction between the fiber and matrix. In case of PF, the trend was different as it is hydrophilic whereas most polymers used for composite fabrication is hydrophobic. Therefore the more hydro-phobic the fiber in OPF-PF composites, less the extent of fiber-matrix interaction, which facilitate sorption process [23]. For example, latex coating make the fibers most hydrophobic and the OPF-PF composites prepared from latex coated fibers exhibit maximum water absorption. 

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