Kenaf fibre is one of the natural fibers that has received much attention of many researchers because of its good properties and flexible use. Kenaf fibre composites have been proposed as interior building materials. In this study, the recycling effect on the kenaf PVC wall panel is focused. The main objective of this study is to determine the mechanical properties of different types of kenaf PVC wall panels. The samples were formulated based on the first and third recycling process. The specimens were subjected to several types of tests, namely, tensile, izod impact, flexural and hardness based on ASTM D3039, ASTM D256, ASTM D7264 and ASTM D785, respectively. The results indicate that the mechanical properties of the third recycled kenaf PVC wall panel product is better than the virgin and first recycled specimen. This shows that the recycling process enhances the mechanical properties of the product. On the other hand, the hardness of the specimen decreases after first recycling due to the reheating effect.
Kenaf (Hibiscus cannabinus) seeds have always being wasted as agricultural waste. Recent studies revealed that the seeds contain high fiber. The purpose of this study is to develop defatted kenaf seeds yellow noodles (DKSY) and assess the nutritional and physicohemical properties of the noodles. Defatted kenaf flour at 25% and 75% were used to make DKSY noodles and compared to wheat yellow noodles (Control). Fresh DKSY noodles were analyzed for their nutritional and physiochemical properties. The ash and fiber contents increased in order of Control > 25% DKSY > 75% DKSY noodles. While total phenolic contents (TPC) was found to be higher in 75% DKSY noodles (138.30 ± 1.63 mg GAE/100 g) than Control noodles. Colour (L, b) and hardness decreased in order of Control > 25% DKSY > 75% DKSY indicating that DKSY noodles developed less quality than Control noodles. However, cooking loss values were found to be in the same order while cooking values exist in the opposite order indicating that. DKSY noodles have better noodle cooking quality. In conclusion, nutritional properties and noodle cooking quality of yellow noodles increased with higher concentration of defatted kenaf flour but the physicochemical properties were compromised. More research needs to be done in order to develop a formulation that can increase all of the attributes studied.
Composite materials have increasingly become crucial in manufacturing engineering products and producing commodity
materials in the major industries including; automotive, aerospace, marine, construction, agriculture and health science.
However, several improvements regarding the strength, dimensional stability and the cost of production are required.
In this study, composite of Kenaf, multi-wall carbon nanotube (MWCNT) and polypropylene (PP) with maleic anhydridegrafted
polypropylene (MAPP) are examined. The results highlight that increasing MAPP loading, in turn, increases the
value of the mechanical properties. The composites are produced by blending kenaf/MWCNT/PP using a Sigma blade
mixer and injection moulding. Injection moulding is a significant operation used to produce plastic products. In the
study, Kenaf core fibre was mixed with MWCNT and polypropylene, in addition to MAPP. The MAPP is added by applying
different percentage (1, 2, 3 and 4 wt. %) during the blending process. The main objective of the study was to analyse the
effects of MAPP concentrations on the mechanical properties of the Kenaf/MWCNT/PP composite. The results of the study
established that MAPP 3 wt. % concentration with MWCNT 3 wt. % loading and Kenaf 30 wt. % filler provide optimum
results for the composites. There was approximately, a 21% enhance in tensile strength of Kenaf 30 wt. %/MWCNT, 3 wt.
%/MAPP, 3 wt. %/PP observed compared to the (without) MAPP composite. The composites with coupling agent stimulate
better filler dispersion between Kenaf, MWCNT and PP observed using a scanning electron microscope (SEM) and fieldemission
scanning electron microscope (FESEM).
Biodegradable materials made from cassava starch and kenaf fibers were prepared using a solution casting method. Kenaf fibers were treated with NaOH, bleached with sodium chlorite and acetic buffer solution, and subsequently acid hydrolyzed to obtain cellulose nanocrystals (CNCs). Biocomposites in the form of films were prepared by mixing starch and glycerol/sorbitol with various filler compositions (0-10 wt%). X-ray diffraction revealed that fiber crystallinity increased after each stage of treatment. Morphological observations and size reductions of the extracted cellulose and CNCs were studied using field emission scanning electron microscopy and transmission electron microscopy. The effects of different treatments and filler contents of the biocomposites were evaluated through mechanical tests. Results showed that the tensile strengths and moduli of the biocomposites increased after each treatment and the optimum filler content was 6%.
Nanocrystalline cellulose (NCC) extracted from lignocellulosic materials has been actively investigated as a drug delivery excipients due to its large surface area, high aspect ratio, and biodegradability. In this study, the hydrophobically modified NCC was used as a drug delivery excipient of hydrophobic drug curcumin. The modification of NCC with a cationic surfactant, cetyl trimethylammonium bromide (CTAB) was used to modulate the loading of hydrophobic drugs that would not normally bind to NCC. The FTIR, Elemental analysis, XRD, TGA, and TEM were used to confirm the modification of NCC with CTAB. The effect of concentration of CTAB on the binding efficiency of hydrophobic drug curcumin was investigated. The amounts of curcumin bound onto the CTAB-NCC nanoparticles were analyzed by UV-vis Spectrophotometric. The result showed that the modified CTAB-NCC bound a significant amount of curcumin, in a range from 80% to 96% curcumin added. Nevertheless, at higher concentration of CTAB resulted in lower binding efficiency.
The fracture behaviour represents the most critical issue in the automotive and aerospace engine fields. Thus, the objective of this study was to estimate and analyze the crack criteria by using the
Mathematical laws that were limited in E 1820 standard and the results affirmed by applying the numerical solutions of ANSYS to estimate the fracture toughness value KIC, besides the energy release rate of biomass composite. The specimens were prepared from different percentage of kenaf mat (KM) and unsaturated polyester resin (UP) 20% KM – 80% UP and 40% KM – 60% UP, respectively, as well the other composite properties which were calculated using the stress-strain data. The fracture characterizations of this composite were carried out using the compact tension (CT) specimen that was commonly used to determine Mode-I fracture properties. The fracture toughness has been found to be independent of pre-crack length. Meanwhile, the tests were performed at room temperature. The numerical simulations of the ANSYS model results demonstrated a good agreement between the experiments computed results of the fracture toughness. The fracture toughness KIC of 20% KM – 80% UP and 40% KM – 60% UP was equivalent to 0.76 MPa√m and 2.0 MPa√m, respectively. Thus, the fracture propagation is dependent on the fibre percentage of the composite. On the other hand, there are unlimited mechanisms of crack paths derived from randomly kenaf mat packs, particularly in the frontal process zone of crack tip.
A sequential solvent extraction scheme was employed for the extraction of antioxidant compounds from kenaf (Hibiscus cannabinus L.) seeds. Yield of extracts varied widely among the solvents and was the highest for hexane extract (16.6% based on dry weight basis), while water extract exhibited the highest total phenolic content (18.78 mg GAE/g extract), total flavonoid content (2.49 mg RE/g extract), and antioxidant activities (p < 0.05). DPPH and hydroxyl radical scavenging, β-carotene bleaching, metal chelating activity, ferric thiocyanate and thiobarbituric acid reactive substances assays were employed to comprehensively assess the antioxidant potential of different solvent extracts prepared sequentially. Besides water, methanolic extract also exhibited high retardation towards the formation of hydroperoxides and thiobarbituric acid reactive substances in the total antioxidant activity tests (p < 0.05). As conclusion, water and methanol extracts of kenaf seed may potentially serve as new sources of antioxidants for food and nutraceutical applications.
Conversion of glucose, empty fruit bunch (efb) and kenaf to levulinic acid over a new hybrid catalyst has been investigated in this study. The characterization and catalytic performance results revealed that the physico-chemical properties of the new hybrid catalyst comprised of chromium chloride and HY zeolite increased the levulinic acid production from glucose compared to the parent catalysts. Optimization of the glucose conversion process using two level full factorial designs (2(3)) with two center points reported 55.2% of levulinic acid yield at 145.2 °C, 146.7 min and 12.0% of reaction temperature, reaction time and catalyst loading, respectively. Subsequently, the potential of efb and kenaf for producing levulinic acid at the optimum conditions was established after 53.2% and 66.1% of efficiencies were reported. The observation suggests that the hybrid catalyst has a potential to be used in biomass conversion to levulinic acid.
The aim of this study was to determine the best parameter for extracting phenolic-enriched kenaf (Hibiscus cannabinus L.) seeds by a pulsed ultrasonic-assisted extraction. The antioxidant activities of ultrasonic-assisted kenaf seed extracts (KSE) were determined by a 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity assay, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical scavenging assay, β -carotene bleaching inhibition assay, and ferric reducing antioxidant power (FRAP) assay. Total phenolic content (TPC) and total flavonoid content (TFC) evaluations were carried out to determine the phenolic and flavonoid contents in KSE. The KSE from the best extraction parameter was then subjected to high performance liquid chromatography (HPLC) to quantify the phenolic compounds. The optimised extraction condition employed 80% ethanol for 15 min, with the highest values determined for the DPPH, ABTS, and FRAP assay. KSE contained mainly tannic acid (2302.20 mg/100 g extract) and sinapic acid (1198.22 mg/100 g extract), which can be used as alternative antioxidants in the food industry.
The enhancement of lignocellulose hydrolysis using enzyme complexes requires an efficient pretreatment process to obtain susceptible conditions for the enzyme attack. This study focuses on removing a major part of the lignin layer from kenaf (Hibiscus cannabinus) while simultaneously maintaining most of the hemicellulose. A two-stage pretreatment process is adopted using calcium hydroxide, Ca(OH)₂, and peracetic acid, PPA, to break the recalcitrant lignin layer from other structural polysaccharides. An experimental screening of several pretreatment chemicals, concentrations, temperatures and solid-liquid ratios enabled the production of an optimally designed pretreatment process for kenaf. Our results showed that the pretreatment process has provide 59.25% lignin removal while maintaining 87.72% and 96.17% hemicellulose and cellulose, respectively, using 1g of Ca(OH)₂/L and a 8:1 (mL:g) ratio of liquid-Ca(OH)₂ at 50 °C for 1.5 h followed by 20% peracetic acid pretreatment at 75 °C for 2 h. These results validate this mild approach for aiding future enzymatic hydrolysis.
A study on the importance of Xylocopa varipuncta (Hymenoptera: Apidae) as pollination agent was conducted at the Setiu Mangrove Forest, Terengganu from September to December 2010. The objective of this study was to identify the pollens collected by carpenter bees (X. varipuncta) in the mangrove community of Setiu Wetlands. A total of 35 types of pollens were collected from the body of X. varipuncta and only 10 types of the pollens were successfully identified. The identified pollens were of Avicennia alba, Lumnitzera racemosa, Sonneratia caseolaris, S. ovata and Rhizophora apiculata from exclusive mangroves, while Suregada multiflora, Melaleuca cajuputi, Derris trifoliata, Acacia auriculiformis and Hibiscus tiliaceus were from non-exclusive mangroves. Melaleuca cajuputi was the highest number of pollen carried by X. varipuncta. This study showed that X. varipuncta is an important pollen carrier in the mangrove community of Setiu Wetlands, Terengganu.
Kajian ini dijalankan bagi menentukan kesan penambahan kalsium karbonat (CaCO3) dan sukrosa ke atas ekstrak roselle dengan menggunakan Kaedah Respon Permukaan. Sebanyak 21 perlakuan digunakan berdasarkan reka bentuk eksperimen Central Composite Rotatable Design (CCRD). Penentuan nilai pH dan Briks telah dijalankan. Bagi nilai pH, model yang didapati adalah 4.03+0.39x1-8.20x2-0.05x1 2-4.16x2 2-0.02x1x2 dengan nilai x1 adalah kalsium karbonat dan nilai x2 adalah sukrosa. Nilai positif pada kepekatan kalsium menunjukkan penambahan kalsium meningkatkan nilai pH ekstrak roselle. Model untuk Briks adalah 8.91 + 0.23x1 + 2.20x2. Nilai positif pada kepekatan kalsium dan sukrosa menunjukkan penambahan kalsium dan sukrosa meningkatkan nilai Briks ekstrak roselle. Penilaian sensori dengan menggunakan panel terlatih (n=8) menunjukkan penambahan sukrosa meningkatkan penerimaan keseluruhan terhadap ekstrak Roselle. Manakala, kesan penambahan kalsium karbonat telah mengurangkan penerimaan keseluruhan kerana ia merendahkan rasa masam.
Kenaf (Hibiscus cannabinus L.) seed is a non-conventional edible oilseed that can be valorized into various food products. There is a recent discovery of kenaf seed beverage (KSB) potential as a novel plant-based beverage. KSB had less crude protein than soybean (SB)but more carbohydrate, magnesium, and phosphorus contents.Levels of crude fat, phytates, oxalates, total saponins, and lipid peroxidability in KSB were lower than SB. Sugar content between KSB and SB were comparable, while antioxidant properties of KSB were superior. Ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS) analysis detected gluconic acid, citric acid, palmitic acid, oleic acid, and 13-hydroxyoctadecadienoic acid in both KSB and SB. Considering its novelty, acute and subacute oral toxicity assessments in male Sprague Dawley rats were conducted. The acute toxicity assessment was performed at a single dose of 9.2 ml/kg body weight of KSB. In the following subacute toxicity assessment, different groups of rats consumed different doses of KSB (3.1, 6.1, and 9.2 ml/kg body weight) daily for 28 days. Rats presented normal behavioral and physiological states in both toxicity studies. Growth, food and water intakes, organ weight, and hematological parameters were unaffected. No mortality was reported. Several alterations in serum biochemical parameters were within the normal range, and unassociated with histopathological changes. The oral lethal dose (LD50) and the no-observed-adverse-effect-level (NOAEL) of KSB in rats was greater than 9.2 ml/kg (=1533 mg/kg) body weight. Interestingly, KSB exhibited comparable effects with soybean beverage (SB) on high-density lipoprotein cholesterol and triglycerides which worth further research Follow-up toxicity assessments in animals and human trials are also recommended to ascertain its long term safety.
The application of natural fibers is rapidly growing in many sectors, such as construction, automobile, and furniture. Kenaf fiber (KF) is a natural fiber that is in demand owing to its eco-friendly and renewable nature. Nowadays, there are various new applications for kenaf, such as in absorbents and building materials. It also has commercial applications, such as in the automotive industry. Magnesium hydroxide (Mg(OH)2) is used as a fire retardant as it is low in cost and has good flame retardancy, while polyester yarn (PET) has high tensile strength. The aim of this study was to determine the horizontal burning rate, tensile strength, and surface morphology of kenaf fiber/PET yarn reinforced epoxy fire retardant composites. The composites were prepared by hybridized epoxy and Mg(OH)2 PET with different amounts of KF content (0%, 20%, 35%, and 50%) using the cold press method. The specimen with 35% KF (epoxy/PET/KF-35) displayed better flammability properties and had the lowest average burning rate of 14.55 mm/min, while epoxy/PET/KF-50 with 50% KF had the highest tensile strength of all the samples. This was due to fewer defects being detected on the surface morphology of epoxy/PET/KF-35 compared to the other samples, which influenced the mechanical properties of the composites.
This study presents an innovative method for synthesizing activated carbon with an exceptionally high surface area (3359 m2 g-1) using kenaf fiber-based biochar through chemical activation. The achieved specific surface area surpasses activated carbon derived from other reported fiber-based precursors. The resulting activated carbon was investigated as electrodes for supercapacitors, revealing a remarkable maximum capacitance of 312 F g-1 at a current density of 0.5 A g-1. An aqueous symmetric supercapacitor employing these high-surface-area electrodes exhibited an outstanding energy density of 18.9 Wh kg-1 at a power density of 250 W kg-1. Notably, the supercapacitor retained exceptional capacitance, maintaining 93% of its initial capacitance even after 5000 charge-discharge cycles.
The electronic database was searched up to July 2020, using keywords, kenaf and roselle, chemical constituents of kenaf and roselle, therapeutic uses of kenaf and roselle. Journals, books and conference proceedings were also searched. Investigations of pharmacological activities of kenaf revealed that this edible plant exhibits a broad range of therapeutic potential including antioxidant, antimicrobial, antityrosinase, anticancer, antihyperlipidemia, antiulcer, anti-inflammatory, and hepatoprotective activities. Kenaf also showed versatile utility as a functional ingredient in food, folk medicine, and animal nutritions, as well as in nanotechnology processes. The exploitation of underexploited kenaf by-products can be a significant part of waste management from an economic and environmental point of view. In addition, kenaf showed comparable nutritional, phytochemical, and pharmacological properties with Hibiscus sabdariffa (Roselle). This review has important implications for further investigations and applications of kenaf in food and pharmaceuticals industry.
Vascular endothelial dysfunction (VED) plays an important role in the initiation of cardiovascular diseases. Roselle, enriched with antioxidants, demonstrates high potential in alleviating hypertension. This study was undertaken to investigate the effects of roselle supplementation of VED and remodelling in a rodent model with prolonged nicotine administration. Male Sprague-Dawley rats (n = 6 per group) were administered with 0.6 mg/kg nicotine for 28 days to induce VED. The rats were given either aqueous roselle (100 mg/kg) or normal saline orally 30 min prior to nicotine injection daily. One additional group of rats served as control. Thoracic aorta was isolated from rats to measure vascular reactivity, vascular remodelling and oxidative stress. Roselle significantly lowered aortic sensitivity to phenylephrine-induced vasoconstriction (Endo-(+) Cmax = 234.5 ± 3.9%, Endo-(-) Cmax = 247.6 ± 5.2%) compared with untreated nicotine group (Endo-(+) Cmax = 264.5 ± 6.9%, Endo-(-) Cmax = 276.5 ± 6.8%). Roselle also improved aortic response to endothelium-dependent vasodilator, acetylcholine (Endo-(+) Rmax = 73.2 ± 2.1%, Endo-(-) Rmax = 26.2 ± 0.8%) compared to nicotine group (Endo-(+) Rmax = 57.8 ± 1.7%, Endo-(-) Rmax = 20.9 ± 0.8%). In addition, roselle prevented an increase in intimal media thickness and elastic lamellae proliferation to preserve vascular architecture. Moreover, we also observed a significantly lowered degree of oxidative stress in parallel with increased antioxidant enzymes in aortic tissues of the roselle-treated group. This study demonstrated that roselle prevents VED and remodelling, and as such it has high nutraceutical value as supplement to prevent cardiovascular diseases.
At present, research in composite materials is being directed at using natural fibres instead of synthetic fibres. Kenaf which is extensively grown in the Far East including Malaysia, has been identified as a bast (stem) fibre with significant market potential. In this work, long and random kenaf fibres (non-woven mat form) were used in the as-received condition and alkalized with a 0.06M NaOH solution. They were combined with polypropylene thin sheets, sandwiched between layers of kenaf fibres and hot-pressed to form natural fibre composites. The mechanical properties of the composites were investigated to observe the effect of fibre alignment, fibre treatment and pre-irradiation method used. A general trend was observed whereby alkalized and long fibre composites gave higher flexural modulus and flexural strength compared with random mat and untreated fibres. The long fibre composites also gave a higher work of fracture. However, the correlation between fibre surface treatment and the work of fracture was less clear. Pre-irradiation on the polypropylene pellets and fibres before the composite is manufactured showed significant improvement on the flexural modulus and flexural strength. The bond performance test performed on the treated composites demonstrated good bonding and interfacial adhesion between the fibre and matrix. However, the method of moulding used need to be improved to optimize the performance of the composites.
Since ancient Egypt, orthosis was generally made from wood and then later replaced with metal and leather which are either heavy, bulky, or thick decreasing comfort among the wearers. After the age of revolution, the manufacturing of products using plastics and carbon composites started to spread due to its low cost and form-fitting feature whereas carbon composite were due to its high strength/stiffness to weight ratio. Both plastic and carbon composite has been widely applied into medical devices such as the orthosis and prosthesis. However, carbon composite is also quite expensive, making it the less likely material to be used as an Ankle-Foot Orthosis (AFO) material whereas plastics has low strength. Kenaf composite has a high potential in replacing all the current materials due to its flexibility in controlling the strength to weight ratio properties, cost-effectiveness, abundance of raw materials, and biocompatibility. The aim of this review paper is to discuss on the possibility of using kenaf composite as an alternative material to fabricate orthotics and prosthetics. The discussion will be on the development of orthosis since ancient Egypt until current era, the existing AFO materials, the problems caused by these materials, and the possibility of using a Kenaf fiber composite as a replacement of the current materials. The results show that Kenaf composite has the potential to be used for fabricating an AFO due to its tensile strength which is almost similar to polypropylene's (PP) tensile strength, and the cheap raw material compared to other type of materials.
Kenaf (Hibiscus cannabinus L.), a potential fibre crop with a desirably high growth rate, could serve as a sustainable feedstock in the production of xylitol. In this work, the extraction of soluble products of kenaf through dilute nitric-acid hydrolysis was elucidated with respect to three parameters, namely temperature, residence time, and acid concentration. The study will assist in evaluating the performance in terms of xylose recovery. The result point out that the maximum xylose yield of 30.7 g per 100 g of dry kenaf was attained from 2% (v/v) HNO3 at 130 °C for 60 min. The detoxified hydrolysate was incorporated as the primary carbon source for subsequent fermentation by recombinant Escherichia coli and the performance of strain on five different semi-synthetic media on xylitol production were evaluated herein. Among these media, batch cultivation in a basal salt medium (BSM) afforded the highest xylitol yield of 0.35 g/g based on xylose consumption, which corresponded to 92.8% substrate utilization after 38 h. Subsequently, fermentation by E. coli in the xylose-based kenaf hydrolysate supplemented with BSM resulting in 6.8 g/L xylitol which corresponding to xylitol yield of 0.38 g/g. These findings suggested that the use of kenaf as the fermentation feedstock could be advantageous for the development of sustainable xylitol production.