Kenaf fiber

A cross-sectional view of kenaf is shown in Figure 3d. The ultimate cells are nearly cylindrical with thick cell walls. Kenaf fibers are shorter and coarser than those of jute. Both chemical (kraft) and mechanical pulps have been produced from kenaf, and successful demonstration mns of newsprint have been made for the Dallas Morning Nem, the St. Petersburg Times, and the Bakersfield Californian with a furnish of 82% kenaf chemithermomechanical pulp and 18% softwood kraft pulp. Kenaf fiber is also considered a substitute for jute and used in sacking, rope, twine, bags, and as papermaking pulp in India, Thailand, and the former Yugoslavia. RoseUe bleached pulp is marketed in Thailand. 

The water sorption of the kenaf system is higher than that of any other system but this could be solved by chemically modifying the kenaf fiber before processing to decrease moisture sorption in the fiber. 

There are several critical issues to consider in this research area. The kenaf fiber must not be degraded by the chemical modification procedures. To maintain the strength of the kenaf fiber, depolymerization or degradation of the cellulose must be avoided. 

Figure 5 shows scanning electron micrographs of hot-pressed control and esterified kenaf fiber. The control fiber (a) shows little tendency to thermally flow under the pressure of the hot press at 190 C whereas the esterified fiber... 

Figure 5 Scanning electron micrographs (x 50) of pressed kenaf fiber control (a) and esterified (80 WPG, b).

Crane, J. C., Kenaf—Fiber-Plant Rival of Jute, Econ, Botany, 1, 334-50 (1947). 

D. Feng and A.R. Sanadi. Effect of compatibilizer on the structure-property relationships of kenaf fiber-polypropylene composites. In Fourth International Conference on Wood-flber-Plastic Composites, Madison, WI, May 12-14, 1997, pp 157-160. 

Serlzawa et al. reported high-performance biomass-based plastics that consist of PLA and kenaf fiber. Adding kenaf fiber to PLA greatly Increased its heat resistance (distortion temperature under load) and modulus and also enhanced its crystallization [48]. 

Serizawa, S., Inoue, K., and Iji, M. (2006). Kenaf-fiber-reinforced poly(lactic acid) used for electronic products. 

Hemp and kenafare fast-growing plants, making them practical sources of fiber in particular, kenaf fibers (taken from the middle of the plant s stalk) show high tensile strength (261 MPa) and modulus (20 GPa). 

Jute and kenaf fibers develop in the phloem, or bast, region of the stem of the plants, and they appear as wedge-shaped bundles of cells intermingled with parenchyma cells and other soft tissues (Figure 7.1) in the transverse sections of the stem. In the growing part of the stem, a circumferential layer of primary fibers develops from the protophloem, but, as vertical growth ceases in the lower parts, secondary phloem fibers develop as a result of cambial activity. In mature plants, which reach a height of 2.5-3.5 m and a basal diameter of about 25 mm, the secondary fiber accounts for about 90% of the total fiber bundles. 

The jute or kenaf fiber of commerce refers to the sheath extracted from the plant stems, whereas a single fiber is a cell bundle that forms one of the links of the mesh. Staple length, as applied to cotton and wool fibers, has no counterpart in the base fibers, and, as a preliminary to spinning, it is necessary to break up the sheaths by a carding process. The fragments so produced are the equivalent of the staple fibers of the cotton and wool industries. 

Chemical Composition of Kenaf Fiber (% Oven Dry Basis)... 

Moreover, in the overlapping region of linear density 1.9 2.4 g/cm/tex, it was noticeable that the kenaf fibers were intrinsically coarse but free from nonfibrous matter, whereas the jute fibers were intrinsically much finer but carried a significant amount of adhering bark. 

Because the properties of the jute and kenaf fiber result from the chemistry of the cell wall components, the basic properties of a fiber can be changed by modifying the basic chemistry of the cell wall polymers. 

The modulus of rupture (MOR), modulus of elasticity (MOE) in bending, and tensile strength (TS) parallel to the board surface are shown in Table 7.16 for fiberboards made from control and acetylated kenaf fiber. Acetylation results in a small decrease in MOR, but about... 

Modulus of Rupture (MOR), Modulus of Elasticity (MOE), and Tensile Strength (TS) Parallel to the Board Surface of Fiberboards Made from Control or Acetylated Kenaf Fiber and 8% Phenolic Resin... 

Medium- to high-density mats can also be used as filtering aids to take partieulates out of waste and drinking water or solvents. Figure 7.11 shows a filter unit that is in plaee to remove metal ions from water that has come from an abandoned coal mine. Jute and kenaf fibers can also be modified to beeome more effieient in removing a wide variety of contaminates from water. 

FIGURE 7.11 Filter unit containing filters made of kenaf fiber (USDA). 

Jute and kenaf fibers are composites made up of a rigid polymer (cellulose) in a thermoplastic matrix (lignin and the hemicelluloses). If a nondeerystallizing reaction condition is... 

Research to develop jute and kenaf fiber thermoplastic alloys is based on first thermoplasti-cizing the fiber matrix as described above, followed by grafting of the modified fiber with a reactive thermoplastic. This type of composite has the thermoplastic bonded onto the jute or kenaf so there is only one continuous phase in the molecule. This is done in one of two ways. In one case, the matrix is reacted with maleic anhydride that results in a double bond in the grafted reacted molecule. This can then be used in vinyl-type additions or in free radical polymerization to either build a thermoplastic polymer or graft one onto the jute or kenaf backbone. In the second method, the matrix is reacted with a bonded chemical and then reacted with a low-molecular-weight thermoplastic that has been grafted with side-chain anhydride groups. 

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