Lignocellulosic fibers surface

Dimensional Analysis and Surface Morphology as Selective Criteria of Lignocellulosic Fibers as Reinforcement in Polymeric Matrices... 

Fig. 9.2 The nonuniform aspect of lignocellulosic fibers (a) curaua, (b) coir, and (c) piassava, with surface details inside white squares...

The work of Valadez-Gonzalez et al. [37] was the only study reported so far to compare two methods, the SFP and the SFF, using a lignocellulosic fiber. In their work, the IFSS of henequen fibers embedded in polyethylene was separately evaluated by means of both SFP and SFF tests. The fibers were previously subjected to different surface chemical treatments aiming at improving the fiber/matrix adhesion. Table 9.3 shows the probable results obtained as a composition of Fig. 11 and Table 4 of Valadez-Gonzalez et al. [37] article. 

Many factors such as adhesion between components, fiber topography, and kinetic parameters of crystallization of semicrystalline matrix have been reported to influence transciystallinity. The transcrystallinity phenomenon in the natural fibers/polypropylene system is affected by the different type of chemical treatment of lignocellulosic materials. Moreover, the ability of natural filler to induce nucleation in polypropylene matrix is also dependent on the kind of chemical modification of surface fibers. Predominant nucleation ability was found for unmodified fibers. However, chemical modification of fiber surface slightly depressed the nucleation of polypropylene matrixes. 

Curaua is a lignocellulosic fiber extracted from the plant Ananus erectfilius. The plants leaves are hard, straight, and have flat surfaces. The leaves are 4—5 cm wide and about 1 m long. It is one of the important natural fibers. 

Liao B, Huang Y, Cong G (1997) Influence of modified wood fibers on the mechanical properties of wood fiber-reinforced polyethylene. J Appl Polym Sci 66 1561-1568 Mani P, Satyanarayan KG (1990) Effects of the surface treatments of lignocellulosic fibers on their debonding stress. J Adhes Sci Technol 4 17-24... 

From Figures 15.13 and 15.14, it has been observed that fiber surface modification also affects the dielectric loss and dissipation factor of resulted UPE matrix-based biocomposites. Furthermore, the mercerized fibers-reinforced polymer composites have been found to have low dielectric loss and dissipation factor followed by raw fibers-reinforced UPE matrix-based composites. It may be due to the incorporation of—COC Hj onto lignocellulosic fibers and partial removal of cellulose chain and surface impurities from fibers surface after surface modification. However, the exact explanation for the above behavior is somewhat difficult as dielectric loss or dissipation factor also depends on fiber orientation [ 16]. Since fibers were inserted in the composite materials in statistical random orientation manner, there may be... 

Modification of lignocellulosic materials surface by copolymerization with vinyl monomers has been reported. The polymerization reaction is initiated at the surface of the fibers by incorporation of peroxides or oxidation-reduction agents, or by treatment with gamma radiation or cold plasma [49]. These reactions form free radicals on the fibers, which initiates the free chain reaction with the vinyl monomers. Different types of properties can be conferred to the fibers using different vinyl monomers, such as increased hydrophilicity with poly(vinyl alcohol), increased hydrophobicity with polystyrene or polyvinylacetate, increased reactivity with polyvinylamine etc. 

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