Natural fiber composites mechanical properties

The influence of physical and chemical treatment methods of natural fibers on mechanical properties was analyzed also. Additionally, the mechanical and other physical properties of the composite are generally dependent on the length, content, and dispersion of fibrous filler and processing parameters. 

Several of these natural fiber composites reach the mechanical properties of glass fiber composites, they are already being used in the automobile and furniture industries. Up to now, the most important natural fibers were jute, flax, and coir. 

An alternative approach to understanding the role which silane-based fiber sizes play in fiber-matrix adhesion has been proposed in which the three-dimensional nature of the interphase formed by the interaction of the sizing agent with the bulk matrix has been shown to be a potential key factor in understanding the role that fiber sizings have in affecting fiber-matrix adhesion and composite mechanical properties. 

Poly(vinyl) alcohol (PVA) is a semi-crystalline polymer, which is already widely used for various applications, either under the form of films or fibers. Compared to other polymers, as it is water-soluble at high temperature, it is easy to process from aqueous solutions. Carbon nanotubes can also be dispersed or solubilized in water via different functionalization approaches. It was quite natural for researchers to try to mix carbon nanotubes and PVA to improve the properties of the neat polymer. In this chapter, we will first examine the different methods that have been used to process CNT/PVA composites. The structures and the particular interaction between the polymer and the nanotube surface have been characterized in several works. Then we will consider the composite mechanical properties, which have been extensively investigated in the literature. Despite the number of publications in the field, we will see that a lot of work is still to be done for achieving the most of the exceptional reinforcement potential of carbon nanotubes. 

Kim, S.J. Moon, J.B. Kim, G.H. Ha, C.S. (2008). Mechanical Properties of Polypropylene/Natural Fiber Composites Comparison of Wood Fiber and Cotton Fiber. Polymer Testing, Vol.27, No. 7, (October 2008), pp. 801-806, ISSN 0142-9418 Kotek, J. Kelnar, L Studenovsky, M. Baldrian J. (2005). Chlorosulfonated polypropylene preparation and its application as a coupling agent in polypropylene-clay nanocomposites. Polymer, Vol. 46, No. 16, (June 2005), pp. 4876-4881, ISSN 0032-3861... 

In FRP products, the silanes are usually applied to the fibers from an aqueous solution. Earlier studies carried out in our laboratory (2) indicated a strong dependence of composite mechanical properties on the concentration of silane in the coating solution, as well as on the silane organofunctionality. Our investigations focus on the effect of silane solution concentration and functionality on the nature and properties of silane coatings deposited from such solutions. Fourier transform infrared... 

Composite materials are combinations of two or more materials with different, often complementary properties (Cheremisinoff 1997). Polymeric natural fiber composites have traditionally been manufactured using short reinforcement fibers dispersed in a matrix (Van de Velde and Kiekens 2001) or compression molded from a nonwoven textile (Mueller and Krobjilowski 2003). These applications usually contain low fiber volume fractions and lack control of fiber angles, resulting in their primary use as nonload carrying components (Svensson 1997). The role of stiff and strong reinforcing fibers in a composite is to carry the load and improve mechanical properties of the matrix material. Regardless of fiber type (carbon. 

Keywords Composites Mechanical properties Natural fibers Supermolecular structure Transcrystalline layer... 

Kim SJ, Moon JB, Kim GH, Ha CS (2008) Mechanical properties of polypropylene/natural fiber composites comparison of wood fiber and cotton fiber. Polym Test 27 801-806... 

Payae Y, Lopattananon N (2009) Adhesion of pineapple-leaf fiber to epoxy matrix the role of surface treatments. Songklanakarin J Sci Technol 31 189-194 Rahman MM, Khan MA (2007) Surface treatment of coir Cocos nucifera) fibers and its influence on the fibers physico-mechanical properties. Compos Sci Technol 67 2369-2376 Rowell RM, Han JS (2000) Characterization and factors effecting fibre properties. In Frolini E, Leao AL, Mattosso LHC (eds) Natural polymers and agrofibres composites. San Carlos, Brazil, pp 115-127... 

One of the most important focus areas of research in the development of natural fiber-reinforced polymer composites is characterisation of the fiber-matrix interface, since the interface alone can have a significant impact on the mechanical performance of the resulting composite materials, in terms of the strength and toughness. The properties of all heterogeneous materials are determined by component properties, composition, structure and interfacial interactions [62]. There have been a variety of methods used to characterize interfacial properties in natural fiber-reinforced polymer composites, however, the exact mechanism of the interaction between the natural fiber and the polymeric matrix has not been clearly studied on a fundamental level and is presently the major drawback for widespread utilization of such materials. The extent of interfacial adhesion in natural fiber-reinforced polymer composites utilizing PLA as the polymer matrix has been the subject of several recent investigations, hence the focus in this section will be on PLA-based natural fiber composites. 

P.K. Bajpai, I. Singh, and J. Madaan, Joining of natural fiber reinforced composites using microwave energy Experimental and finite element study. Mater. Des. 35, 596-602 (2012). P. K. Bajpai, I. Singh, and J. Madaan, Comparative studies of mechanical and morphological properties of polylactic acid and polypropylene based natural fiber composites. Reinf. Plast. Compos. 31, 1712-1724 (2012). 

As the performance of the composite is profoxmdly dominated by the micromechanical deformation process, its knowledge and control are critical for the improvement of composite properties. The effect of particle characteristics and interfacial adhesion on the micromechanical deformation processes in PP-wood composites was investigated by Renner et al. [7]. They proposed a failure map as well as the practical results and considered the influence of matrix characteristics on deformation and failure in PP-natural fiber composites in other research [24]. Hietala et al. [78] studied the effect of chemical pre-treatment and moisture content of wood chips on the wood particle aspect ratio during the processing and mechanical properties of WPCs. The use of pretreated wood chips enhanced the flexural properties of the wood chip-PP composites. Moreover, the use of undried wood chips compared to dried one can improve and reduce the flexural strength and flexural modulus, respectively. On the other hand, they concluded that the use of pretreated and undried wood chips lead to the highest aspect ratio after compounding. The effect of composition and the incorporation... 

Gutierrez et al. [50] investigated the effect of replacing part of Portland cement by pozzolans as silica fume, fly ash and metakaolin on the mechanical properties of cement mortar reinforced with synthetic and natural fibers. The mechanical behavior and durability of composite materials was improved by replacing 15 wt% of cement with metakaolin or silica fume however, because of its low pozzolanic power, fly ash had no effect on the durability of these materials. Khorami and Ganjian [62] increased flexural strength in 20% of cementitious materials reinforced with straw fibers and eucalyptus, by replacing 5 wt% of Portland cement with silica fume. 

Recently, new compounding methods have been investigated to produce long, natural fiber-reinforced thermoplastic pellets and improve composite mechanical properties [31, 32]. For example, pellets have been formed by melt impregnation of continuous natural fiber yarns by pultrusion followed by cooling and chopping. Another method involves commingling of continuous forms of natural and synthetic fibers that are then heated, consolidated, and chopped. 

Various researchers had found that stalk fibers have better properties than that of the other parts of plant fiber and indicated that they can be used for composite and other industrial applications (Reddy and Yang, 2009). Natural fiber composite laminates with distributed areca and maize stalk fibers using phenol formaldehyde were investigated (Kumar, 2008). Composite laminates were prepared with different proportions of phenol formaldehyde and fibers. Mechanical test such as tensile test, adhesion test, moisture... 

In order to improve this characteristic, the plant fibers are subjected to several types of surface modifications including physical [1,6], chemical [4,5], or biological [7, 8] treatments. A review of the various types of surface modification undertaken to obtain natural fiber composites with mechanical properties comparable to those of their synthetic counterparts is presented in this chapter. 

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