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Production of kenaf polyols (KP) via liquefaction process was carried out using polyethylene glycol 400 and glycerol as the liquefying solvent. Optimization of parameters such as temperature, time, and the ratio of catalyst composition was done extensively. The effect of the hybridization of inorganic acid (sulphuric acid) and organic acid (lactic acid) as the liquefaction catalyst on the liquefaction product was studied. The results demonstrated that the lowest amount of residue (10.1%) was obtained at 160 °C with 3:1 (sulphuric acid: lactic acid) ratio of catalyst composition for 90 min. The hydroxyl (OH) number and viscosity of the kenaf polyol were examined. FTIR and NMR analyses revealed that most kenaf cellulose, hemicellulose, and lignin were degraded. XRD analysis was employed to examine the crystallinity index of kenaf residues (KR) at different temperatures, times, and catalyst ratio compositions. The morphology of KR at different temperatures was examined by using SEM analysis. The results showed that a smooth-surface KR was obtained at the optimum temperature (160 °C), indicating most of the cellulose was already decomposed at 160 °C. The optimized KP with OH number of 335.6 mg KOH/g and viscosity of 690 cP was used for the making of bio-based rigid polyurethane foam which is denoted as KPUF. The properties of KPUF and PUFs based petroleum polyol (PPUF) were compared. The density of KPUF (68.2 kg/m3) is lower compared to PPUF (131.9 kg/m3). The cellular structure and larger average cell diameter (0.617 mm) of KPUF enhance the water absorption ability which demonstrated that KPUF is capable to be utilized as growing media in the hydroponic system. [ABSTRACT FROM AUTHOR]

Highlights • Properties of needle punched thick EFB and fine kenaf fibres were compared. • The performance of EFB fibre in nonwoven fabric preform was revealed. • Effects of type of fibres and nonwoven fabrics on physical properties of PP composite were studied. • EFB has higher tensile strength in nonwoven preform but lower in composite as compared with kenaf. Abstract The empty fruit bunch (EFB) and kenaf polypropylene (PP) nonwoven composites in this study were prepared via needle punching nonwoven process followed by compression moulding. As compare to the fine kenaf fibre, the thick and rough fibre such as EFB is uncommon in the nonwoven process although it could be a cheap alternative material. To establish EFB as a new raw material in needle punching nonwoven composite, the effect of type of fibre, fibre content, fabric direction and fabric weight on mechanical properties of polypropylene nonwoven preform and composite was studied. Statistical Analysis of Variance (ANOVA) has been used to analyse the effects of the parameter to the preform and composite properties. The punching density, fabric weight and natural fibre content were set at 0, 150 and 300 punches/cm2; 300, 400 and 700 g/m2; 40, 50 and 60%, respectively. This study showed that type of fibre has significant influence on the tensile strength of the nonwoven preform especially at 60% fibre content as compare to the nonwoven composite. The fibre content and fabric direction were also the main factors affecting the tensile strength and the tensile elongation of the nonwoven preform. It was proven that EFB has great potential applications as nonwoven fabric and alternative reinforcement material in nonwoven composites. [ABSTRACT FROM AUTHOR]

Kenaf core pulp has been successfully autohydrolysed using an autoclave heated in oil bath at various reaction temperature at 100, 120 and 140 °C. Membranes, hydrogels and aerogels were then prepared from autohydrolysed kenaf in urea/alkaline medium by casting on the glass plate, by using epichlorohydrin (ECH) as cross-linker via stirring and freeze-drying method, respectively. The autohydrolysis process reduced the molecular weight of cellulose and enhanced cellulose solubility and viscosity. Structure and properties of the regenerated products were measured with Field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), Ultraviolet–visible (UV–Vis) spectrophotometer and swelling testing. As the autohydrolysis temperature increased, the porosity of cellulose membranes (as seen from the morphology) increased. The autohydrolysis process improved the swelling porperties and transparency of regenerated cellulose hydrogels. This finding is expected to be useful in reducing molecular weight of cellulose in order to produce regenerated bio-based cellulose materials. [ABSTRACT FROM AUTHOR]

Regenerated cellulose film with better mechanical properties was successfully produced by introducing aldehyde crosslinker during the regeneration process. The cellulose source material was derived from kenaf core powder and dissolved in LiOH/urea solvent at -13 °C to form a cellulose solution. The cellulose solution was cast and coagulated in a crosslinker bath at different percentages of glutaraldehyde (GA) and glyoxal (GX) to form a regenerated cellulose film. According to Fourier transform infrared spectroscopy (FTIR) spectra, the hydroxyl group of the cellulose was reduced, reducing the percentage of swelling as the percentage of crosslinker was increased. X-ray diffraction (XRD) patterns showed that the crystallinity index of the crosslinked film was decreased. The pore size of the films decreased as the percentage of crosslinker was increased, resulting in decreased film transparency. The pore volume and percentage of swelling in water of the films also increased with decreases in the pore size as the percentage of crosslinker was increased. The tensile strengths of the GA- and GX-crosslinked films increased by 20 and 15% with the addition of 20% of each crosslinker, respectively. [ABSTRACT FROM AUTHOR]

Bleached kenaf core pulps (BKC) were hydrolyzed in H 2 SO 4 (0.5 M) at different time (0 min to 90 min) at room temperature. After the hydrolysis process, the viscosity average molecular weight ( M ŋ ) for BKC sample has reduced from 14.5 × 10 4 to 2.55 × 10 4 . The hydrolyzed BKC was then dissolved in NaOH:urea:water and in LiOH:urea:water mixed solvent at the ratio of 7:12:81 and 4.6:15:80.4, respectively. The increased in hydrolysis time has decreased M ŋ of cellulose leading to easy dissolution process. Higher porosity and transparency with lower crystallinity index (CrI) of regenerated membrane produced can be achieved as the M ŋ reduced. The properties of membrane were observed through FESEM, UV–vis spectrophotometer and XRD. This study has proven that acid hydrolysis has reduced the M ŋ of cellulose, thus, enhanced the properties of regenerated membrane produced with assisted by alkaline/urea system. [ABSTRACT FROM AUTHOR]

The hydrothermal pretreatment on kenaf core pulp (KCP) was carried out using an autoclave heated in a oil bath at 140 °C for 0.5/1/3/5 h. The hydrothermal pretreated kenaf (HPK) was dissolved in a LiOH/urea aqueous solution and subsequently used to produce cellulose membrane and hydrogel. The effects of hydrothermal pretreatment time on solubility, viscosity, crystallinity and morphology of the cellulose membrane and hydrogel were investigated. The hydrothermal pretreatment leads to higher cellulose solubility and higher viscosity of the cellulose solution. The formation of cellulose II and crystallinity index of the cellulose membrane and hydrogel were examined by X-ray diffraction (XRD). The pore size of the cellulose membrane and hydrogel displayed an upward trend with respect to the hydrothermal pretreatment period observed under a field emission scanning electron microscope (FESEM). This finding provides an efficient procedure to improve the solubility, viscosity and properties of regenerated cellulose products. [ABSTRACT FROM AUTHOR]

Cellulose was extracted from kenaf core powder by a series of bleaching processes and subsequently dissolved using an alkaline LiOH/urea solvent at low temperatures. The produced cellulose solution was mixed with polyvinyl alcohol (PVA) with different ratios of cellulose/PVA and coagulated to produce regenerated transparent films. The films were then air dried to produce transparent film. The effects of PVA content on tensile index, transparency, pore size, and printability of the films were studied. A slight reduction of 7% on the tensile index of the film was observed when the content of PVA increased to 10%. Nevertheless, the addition of 10% of PVA increased the porosity of the regenerated cellulose/PVA film, while the transparency of the film increased by 10%. The films were color-printed using a laser printer and can be recycled, in which the printed ink can be removed easily from the films with higher amount of PVA content. In addition, the films can be reprinted repeatedly several times. [ABSTRACT FROM AUTHOR]

Kenaf (Hibiscus cannabinus L.) is a relatively new industrial crop which has been identified as an alternative source of fiber in the papermaking industry in Malaysia. In this study, experimental unbleached kenaf kraft paper samples were used as a substrate to produce water-resistant paper by employing a special coating. In the preparation of the coating formulation, commercially precipitated calcium carbonate (PCC) was used as the filler, in addition to 0 to 0.32 w/w g of hydrophobic stearic acid (SA). Polymer latex (PL) was added at 0.4 to 0.16 w/w g into the coating compound to control the surface roughness of the samples. The paper morphology was examined by employing a scanning electron microscope (SEM). Hydrophobic kenaf kraft paper prepared in this study had water contact angle (θ) greater than 90°. Hydrophobic paper made with formulation PL4c resulted in the highest value contact angle of 147°. The process of surface coating by dipping increased the water contact angle and this treated paper achieved a high hydrophobic level. For mechanical properties, the coated kenaf paper showed decreasing tensile strength as the addition of stearic acid increased. [ABSTRACT FROM AUTHOR]

Natural fibers such as kenaf have been studied extensively as a reinforcing phase and received major attention recently due to their renewability, biodegradability, and high strength comparable to other synthetic fibers. In this study, nano-crystalline cellulose (NCC) was produced from kenaf core wood using the acid hydrolysis method. Kenaf core was alkali treated with a 4 wt% of sodium hydroxide solution and subsequently bleached using sodium chlorite in acidic buffer. The resulting white, bleached kenaf core was hydrolyzed in 64 wt% sulfuric acid (H2SO4) to obtain NCC. The resulting NCC suspension was characterized using X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) analysis, and scanning transmission electron microscope (STEM). Hydrolysis with highly concentrated H2SO4 further increased the crystallinity of bleached kenaf core cellulose and reduced the dimension of cellulose to nano scale. FTIR results showed that with each subsequent treatment, hemicellulose and lignin were removed, while the chemical functionalities of cellulose remained after the acid hydrolysis treatment. XRD peaks shown by bleached kenaf core were characteristic of cellulose I, which was reaffirmed by the DSC results. The diameters of NCC obtained from kenaf core were found to be in the range of 8.5 to 25.5 nm with an average aspect ratio of 27.8. [ABSTRACT FROM AUTHOR]

In this study, the sorption of Cu(II) ions from aqueous solution onto NaOH-treated kenaf core fibres was investigated. The kenaf core fibres were milled into different sizes and treated with NaOH before being used to investigate their efficiency in removing Cu(II) ions from aqueous solutions. Sorption studies were performed at a pH value of 5. Sorption of the Cu(II) ions increased and the sorption yield decreased with increasing initial Cu(II) ion concentration. The sorption data were correlated with the Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherms. The values of the correlation coefficients obtained indicated that the Langmuir isotherm fitted the experimental data better than the Freundlich and D-R isotherms. Kenaf core fibres with fibre sizes in the range 150-300 μm possessed the highest sorption capacity. The calculated parameters of the isotherms suggest that the uptake of Cu(II) ions occurred at the homogeneous active sites on the surfaces of the kenaf core fibres. [ABSTRACT FROM AUTHOR]

Abstract: Chemically modified kenaf core fibres were prepared via esterification in the presence of citric acid (CA). The adsorption kinetics and isotherm studies were carried out under different conditions to examine the adsorption efficiency of CA-treated kenaf core fibres towards methylene blue (MB). The adsorption capacity of the kenaf core fibres increased significantly after the citric acid treatment. The values of the correlation coefficients indicated that the Langmuir isotherm fitted the experimental data better than the Freundlich isotherm. The maximum adsorption capacity of the CA-treated kenaf core fibres was found to be 131.6mg/g at 60°C. Kinetic models, pseudo-first-order, pseudo-second-order and intraparticle diffusion, were employed to describe the adsorption mechanism. The kinetic data were found to fit pseudo-second-order model equation as compared to pseudo-first-order model. The adsorption of MB onto the CA-treated kenaf core fibres was spontaneous and endothermic. [Copyright &y& Elsevier]

Cellulose carbamate (CC) was produced from kenaf core pulp (KCP) via a microwave reactor-assisted method. The formation of CC was confirmed by Fourier transform infrared spectroscopy and nitrogen content analysis. The degree of substitution, zeta potential and size distribution of CC were also determined. The CC was characterized with scanning electron microscopy, X-ray diffraction and thermogravimetry analysis. The CC particles were then dispersed in silicone oil to prepare CC-based anhydrous electric stimuli-responsive electrorheological (ER) fluids. Rhelogical measurement was carried out using rotational rheometer with a high voltage generator in both steady and oscillatory shear modes to examine the effect of electric field strength on the ER characteristics. The results showed that the increase in electric field strength has enhanced the ER properties of CC-based ER fluid due to the chain formation induced by electric polarization among the particles. [ABSTRACT FROM AUTHOR]