Warwick D. Raverty

Chemical and Morphological Characteristics of Malaysian Cultivated Kenaf (Hibiscus cannabinus) Fiber

In this study, an attempt is made to understand the chemical and morphological characteristics of Malaysian cultivated kenaf fractions (bast, core, and whole stem). Results based on morphologyand chemical analysis indicate that bast and core fiber fractions in the kenaf are significantly different, although the chemical composition of kenaf is quite similar to the woody mass. In the case of whole stem fibers, it is concluded that the effective length of fibers from the whole stem is reasonably good for the purpose of making printing papers.

Effect of chitosan addition on the surface properties of kenaf (Hibiscus cannabinus) paper

The present paper studies the effect of chitosan, cationic starch and polyvinyl alcohol (PVA) as sizing agents to enhance surface properties of kenaf paper. The polymers were incorporated into the sheets by spray application. The results clearly showed that the addition of chitosan to a sheet formed from beaten fibers had excellent improvement in surface properties, compared to the effect of other additives. Sizing quality of cationic starch fairly matched with the sizing quality of chitosan, however, it was able to reduce the water absorption potential of paper more than chitosan at a same concentration. In most other properties, particularly the most important property for printing papers, surface smoothness, chitosan-sized papers are superior to the paper sized with cationic starch or PVA.

Functionalised pseudo-boehmite nanoparticles as an excellent adsorbent material for anionic dyes

Pseudo-boehmite has been functionalised with L-lysine by refluxing an aqueous solution containing these two reactants overnight. The resulting nanosized (<10 nm) product is insoluble in water and has been characterised by solid-state NMR spectroscopy, powder X-ray diffraction analysis, N2 adsorption–desorption analysis and zeta potential measurements. The affinity of this new nanostructured organic–inorganic hybrid material for anionic dyes has been quantified using UV-vis spectrophotometry and by constructing the adsorption isotherms for Acid Blue 9 (AB9), Acid Yellow 23 (AY23), and Acid Red 37 (AR37). Elemental/micro analyses indicate that one lysine molecule is covalently bonded to every 8 nm2 of the functionalised material giving a composition [(AlOOH)230·(H2O)86·(C6N2O2H15)]. The introduction of the positively charged amino groups resulted in a tremendous increase in dye affinity in contrast to the unfunctionalised material. The adsorption isotherms of the functionalised pseudo-boehmite were fitted to the Langmuir model and yielded equilibrium binding constants (Ka) of 2.6 × 103 M−1 for AB9, 1.5 × 105 M−1 for AY23 and 8.4 × 104 M−1 for AR37. AR37 gave a higher monolayer coverage (Cm) value of 0.13 mmol g−1 than AB9 (0.085 mmol g−1) and AY23 (0.081 mmol g−1). Dye adsorption is correlated with surface coverage of L-lysine and, in the case of AR37, two dye molecules are concluded to be adsorbed per L-lysine while for AY23 a multi-point interaction is proposed to result in a lower dye capacity and a relatively higher affinity of this dye for FPB when compared with AR37.

Printability of Sized Kenaf (Hibiscus cannabinus) Papers

This article reviews the effect of chitosan, cationic starch and polyvinyl alcohol as sizing agents to improve printability properties of kenaf handsheets. The polymers were incorporated into the sheets by spray application. This study clearly demonstrated that the use of chitosan could improve the printability and print quality of kenaf paper in terms of water and oil absorption, ink penetration, print density and gloss for offset printing. Both PVA-sizing and cationic starch sizing gave print densities and ink penetrations than were intermediate between chitosan and the unsized control sheet, which gave the lowest values for these properties. Kenaf paper sized with chitosan gave the best mix of desirable printing paper properties and was superior to kenaf papers sized with either cationic starch or PVA.

Effect of Totally Chlorine Free and Elemental Chlorine Free Sequences on Whole Stem Kenaf (Hibiscus cannabinus) Pulp Characteristics

ABSTRACT Totally chlorine free (TCF) and elemental chlorine free (ECF) single and multistage sequences were used to bleach whole stem kenaf pulp. The results indicated that in contrast to unbleached kraft wood pulps, kraft kenaf pulps can be easily bleached to a brightness of 91.4% using a four-stage TCF [Q1(PO)Q2P] bleaching sequence. The ECF bleaching pulps had slightly higher selectivity and yield than those of the TCF bleached pulps. The strength properties of the TCF [Q1(PO)Q2P] and ECF (D1ED2EP) bleached pulps were comparable, with the exception of tear index and tensile index, which were slightly higher and lower for TCF pulps, respectively.

Effect of Accelerated Aging on Properties of Kenaf(Hibiscus cannabinus) Paper Sized with Various Polymers

ABSTRACT The effect of aging on the properties of paper sized with chitosan, cationic starch, and PVA was investigated under accelerating conditions (90°C and 50% RH). The observations from this study demonstrate that the brightness and pH of papers decrease with an increase in aging time. At each aging time, paper sized with chitosan shows the highest reduction in brightness, whereas decreases in brightness in papers sized with PVA and cationic starch do not show much difference. The results demonstrate that paper sized with any of the polymers gave higher levels of tear index, tensile index, and folding endurance than the control sheet. Statistical analysis indicated that the polymers used in this experiment have a statistically significant effect on the folding endurance of sized paper that was highest in the cases of PVA and chitosan.