Natural fibers mechanical properties

V.K. Thakur, A.S. Singha, and M.K. Thakur, Green Composites from Natural Fibers Mechanical and Chemical Aging Properties. Int. J. Polym. Anal. Charact. 17, 401-407 (2012). 

Thakur VK, Singha AS, Misra BN (2011) Graft copolymerization of methyl methacrylate onto cellulosic biofibers. J Appl Polym Sci 122(l) 532-544. doi 10.1002/app.34094 Thakur VK, Singha AS, Thakur MK (2012a) Green composites from natural fibers mechanical and chemical aging properties. Int J Polym Anal Charact 17(6) 401-407. doi 10.1080/... 

Thakur, V. K, Singha, A. S., and Thakur, M. K. [2012a]. Green composites from natural fibers Mechanical and chemical aging properties. International Journal of Polymer Analysis and Characterization, 17[6], 401-407. doi 10.1080/1023666X.2012.668665. 

Commercial production of PVA fiber was thus started in Japan, at as early a period as that for nylon. However, compared with various other synthetic fibers which appeared after that period, the properties of which have continuously been improved, PVA fiber is not very well suited for clothing and interior uses because of its characteristic properties. The fiber, however, is widely used in the world because of unique features such as high affinity for water due to the —OH groups present in PVA, excellent mechanical properties because of high crystallinity, and high resistance to chemicals including alkah and natural conditions. 

Rubber. The mbber industry consumes finely ground metallic selenium and Selenac (selenium diethyl dithiocarbamate, R. T. Vanderbilt). Both are used with natural mbber and styrene—butadiene mbber (SBR) to increase the rate of vulcanization and improve the aging and mechanical properties of sulfudess and low sulfur stocks. Selenac is also used as an accelerator in butyl mbber and as an activator for other types of accelerators, eg, thiazoles (see Rubber chemicals). Selenium compounds are useflil as antioxidants (qv), uv stabilizers, (qv), bonding agents, carbon black activators, and polymerization additives. Selenac improves the adhesion of polyester fibers to mbber. 

Key Words —Nanotubes, mechanical properties, thermal properties, fiber-reinforced composites, stiffness constant, natural resonance. 

Table 2 Mechanical Properties of Natural Fibers in Comparison to Conventional Reinforcement Fibers...

The mechanical properties of natural fibers depend on cellulose type because each type of cellulose has a specific cell geometry and the geometrical conditions determine the mechanical properties. 

Analog-to-glass fibers silanes are used as coupling agents for natural fiber polymer composites. For example, the treatment of wood fibers with product A-175 improves wood dimensional stability [53]. In contrast, a decrease of mechanical properties was observed for coir-UP composites after a fiber modification with di-chloromethylvinyl silane [54]. The treatment of mercer-... 

Aside from SMC molded plastics, BMC molded natural fiber plastics with good mechanical properties can be produced. Owolabi et al. [59] made such plastics with coir fibers, their basic recipe is shown in Table II. 

Generally, the mechanical and physical properties of natural fiber-reinforced plastics only conditionally reach the characteristic values of glass fiber-reinforced systems. By using hybrid composites made of natural fibers and carbon fibers or natural fibers and glass fibers, the... 

Additionally, the dependence of the mechanical properties on humidity is clearly reduced because of the moisture repellency of glass fibers [69]. The moisture absorption of composites is clearly smaller when natural fibers are replaced by glass fibers [65]. 

The mechanical and physical properties of natural fibers vary considerably, as it is with all natural products. These properties are determined by the chemical and structural composition, which depend on the fiber type and growth circumstances. With this cellulose, the main component of all natural fibers varies from fiber to fiber. 

The moisture sensibility is remarkable, certain natural fibers can easily be influenced by environmental effects. Generally speaking, the mechanical properties are lowered with rising moisture content. 

Natural fibers compete with technical fibers, such as glass fibers or carbon fibers, as reinforcements for plastics. The advantages of technical fibers are their good mechanical properties, which vary only a little, but their recycling is difficult. 

The mechanical properties of composites are mainly influenced by the adhesion between matrix and fibers of the composite. As it is known from glass fibers, the adhesion properties could be changed by pretreatments of fibers. So special process, chemical and physical modification methods were developed. Moisture repel-lency, resistance to environmental effects, and, not at least, the mechanical properties are improved by these treatments. Various applications for natural fibers as reinforcement in plastics are encouraged. 

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. 

Table 3 Physical and Mechanical Properties of Some Natural Fibers...

The term s plastic, polymer, resin, elastomer, and reinforced plastic (RP) are some-what synonymous. However, polymer and resin usually denote the basic material. Whereas plastic pertains to polymers or resins containing additives, fillers, and/or reinforcements. Recognize that practically all materials worldwide contain some type of additive or ingredient. An elastomer is a rubberlike material (natural or synthetic). Reinforced plastics (also called composites although to be more accurate called plastic composites) are plastics with reinforcing additives, such as fibers and whiskers, added principally to increase the product s mechanical properties. 

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