Kenaf acetylation

Kenaf bast fiber lignins (Figure 5.11a), contain striking amounts of acetate [37,312] over 50% of the units appear to be acetylated. Figures 5.11b through 5.11e show the... 

Jute and kenaf, like most vegetable fibers, contain a proportion of acetyl groups that are readily hydrolyzed by dilute alkali to acetic acid. Estimation of the quantity of acetic acid produced per unit weight of fiber then provides an index of the acetyl content. 

Soutar and Brydon s results show no significant difference between H. cannabinus and H. sabdariffa, which is, perhaps, surprising in view of the difference between the two jute varieties, but the acetyl content does appear to offer a means of differentiating between jute and kenaf. For such a comparison to be valid, of course, there must have been no prior treatment of the fiber with alkali, which occasionally happens in chemical retting experiments. 

By far, maximum research has been done on the reaction of acetic anhydride with cell wall polymer hydroxyl groups to give an aeetylated fiber. Jute [37 39] and kenaf [40,41] have been reacted with acetic anhydride. Without a strong catalyst, acetylation using acetic anhydride alone levels off at approximately 20 weight percent gain (WPG). The equilibrium moisture content (EMC) and thickness swelling at three relative humidities for fiberboards made from these fibers is shown in Table 7.13. 

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... 

Rate and Extent of Thickness Swelling in Liquid Water of Kenaf Fiberboards Made from Control and Acetylated Fiber and a Phenolic Resin [Resin content of boards 8%]... 

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... 

Recently, the presence of hydroxydnnamate esters consisting of ferulic and p-coumaric acids esterified to long-chain fatty alcohols (C20 to C28) and co-hydroxyfatty adds (C22 to 23) in abaca fiber has been reported by del Rio et al. [72]. del Rio et al. [73] also report that native lignin in kenaf, jute, sisal, and abaca is at least partially acetylated. 

The effect of chemical modification of cellulose nanofibers on the properties of PLA nanocomposites has been investigated (44). Ac-etylated nanofibers, with a degree of substitution 1.07, were isolated from acetylated kenaf fibers by a mechanical procedure. The acet-ylated nanofibers were found to be more hydrophobic. Both crystallinity and thermal stability of acetylated nanofibers were lower in comparison to the non-acetylated nanofibers. 

H. Ismail, A.H. Abdullah, and A.A. Bakar, Influence of acetylation on the tensile properties, water absorption, and thermal stabflity of (High-density polyethylene)/(soya powder)/ (kenaf core) composites. J. Vinyl Addit. Technol. 17,132-137 (2011). 

Modification of acetylated cellulose nanofibers from kenaf using acetic anhydride [68]... 

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