Vegetable fibers properties

A summary of important properties of some vegetable fibers is given in Table... 

Table3.2 Properties of some vegetable fibers (adaptedfrom Rohatgi et al, 1992).

Vegetable fiber, glue binder Vulcanized fiber 212 Resists oil and water to 212°F. Low cost, good mechanical properties. Resists gasoline, oils, greases, waxes, many solvents. 

Stout has written a detailed review on jute and kenaf. X-ray diffraction patterns show the basic cellulose crystal structure, although in jute and kenaf the crystalline orientation is high and the degree of lateral order is lower than in flax. Batra" in a comprehensive review has highlighted the morphological structures and physical, mechanical and chemical properties of other long vegetable fibers. 

A. K. Bledzki, S. Reihmane, and J. Gassan, Properties and modification methods for vegetable fibers for natural fiber composites, J. Appl. Polym. Sci., 59 (1998) 1329-1336. 

It has been mentioned earlier that vegetable fibers other than cotton and kapok are multicellular. The mechanical properties of these fibers, therefore, reflect an interaction between their ultimates and their middle lamella substances ramie is an exception because the size of its ultimates is large enough to act as a fiber. 

Vegetable fibers also show time-dependent properties associated with other polymeric materials. There is, however, only limited data available, which analyzes creep, relaxation, or strain-rate behavior of vegetable fibers. 

The interested reader is advised to read other reviews of the subject. For instance, Biagiotti, Puglia, and Kenny [27] provide a good comprehensive review of the structure, processing, and properties of vegetable fibers. 

Fibers have been widely used in polymeric composites to improve mechanical properties. Cellulose is the major substance obtained from vegetable fibers, and applications for cellulose fiber-reinforced polymers have again come to the forefront with the focus on renewable raw materials. Hydrophilic cellulose fibers are very compatible with most natural polymers. The reinforcement of starch with ceUulose fibers is a perfect example of a polymer from renewable recourses (PFRR). The reinforcement of polymers using rigid fillers is another common method in the production and processing of polymeric composites. The interest in new nanoscale fillers has rapidly grown in the last two decades, since it was discovered that a nanostructure could be built from a polymer and layered nanoclay. This new nanocomposite showed dramatic improvement in mechanical properties with low filler content. Various starch-based nano-composites have been developed. 

Baley C, Busnel F, Grohens Y, Sire O (2006) Influence of chemical treatments rai surface properties and adhesion of flax fiber-polyester resin. Compos A 37(10) 1626-1637 Barton F, Akin D, Morrison W, Ulrich A, Archibald D (2002) Analysis of fiber content in flax stems by near-infrared spectroscopy. J Agric Food Chem 50(26) 7576-7580 Basu S, Bhattacharyya J (1951) Mildew of complex vegetable fibers. J Sci Ind Res 10B(4) 91-93 Berkley E (1949) Certain variations in the structure and properties of natural cellulose fibers. Text Res J 19(60) 91-93... 

Mukherjee PS, Satyanarayana KG (1984) Structure and properties of some vegetable fibers -Part 1 Sisal fiber. J Mater Sci 19 3925-3934... 

Satyanarayana KG, Ravikumar KK, Sukumaran K, Mukherjee PS, Pillai SGK, Kulkami AG (1986) Stmcture and properties of some vegetable fibers-Part 3 Talipot and palmyrah fibers. 

It should be noted, however, that the thermal and mechanical properties of vegetable fiber reinforced polymer composites are notoriously lower than those of similar composites reinforced with synthetic fibers (e.g., carbon, glass, aramid) [1, 2,12]. The above-mentioned techniques, i.e., fiber drying and surface treatment or the addition of a compatibilizer, are mostly not enough to adjust the properties of vegetable fiber reinforced polymers to the desired level. Moreover, even though these treatments enhance adhesion, there is some controversy in the literature about their effect on the mechanical properties of the fiber itself and even when a more pronoxmced gain is noticed after treatment, the improvement for the composite is often within the scatter of the results. In addition, the cost and environmental impact of some of these treatments, especially of those more elaborated, often prevent their industrial scale applications. 

Indeed, a wider use of vegetable fibers in composites replacing synthetic fibers, or more realistically, glass fiber, in either thermoset (mainly unsaturated polyester) or thermoplastic (mainly polyolefins) composites is mainly limited by their comparatively poorer mechanical properties, higher moisture absorption and lower compatibility to... 

The lignocellulosic materials mostly used as fillers in thermoplastic composites include wood flour, starch, rice husk and a wide variety of vegetable fibers available such as jute, sisal, flax, hemp, coir, banana, pineapple, among others. And whenever vegetable fiber reinforced thermoplastic composites with higher properties are needed, possible solutions include improved adhesion, better fiber orientation, and filler hybridization with synthetic fibers or mineral fillers. The latter solution is an intermediate alternative regarding environmental friendliness, cost, weight and performance compared to an all synthetic composite [12,26]. 

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