Search Results (198)

The demand for biodegradable, recyclable, natural composites with lightweight structures is driven by the fact that advanced structures can withstand quasi-static and dynamic loadings. This study examined the energy-absorbing characteristics of interlocking periodic honeycomb sandwich structures made from short sugar palm, kenaf, and pineapple leaf fibres (PALFs) reinforced with a polylactic acid (PLA) composite. The biodegradable sugar palm, kenaf, and PALF/PLA composite sheets were subjected to hot compression and cut into single- and double-slot square plates. The interlocking technique was used to assemble periodic two-dimensional square-honeycomb sandwich structures. Moreover, new and recyclable PLA-based composites with three fibres were tested for tensile properties. The biodegradable PLA-based composite honeycomb sandwich structure underwent a quasi-static compression test. Finite element modelling was used to simulate the load–displacement curve, energy-absorption characteristics, and failure behaviour, incorporating tensile properties and geometric imperfections. The results revealed that the double-slot design of the pineapple/PLA sandwich structure significantly increased by 1.33 times compared to the sugar palm/PLA sandwich structure. Notably, it reduced the compressive strength of recyclable pineapple/PLA (66.4%) and recyclable sugar palm/PLA (31.5%) composite sandwich structures compared to the new pineapple/sugar palm PLA-based composite. In addition, finite element analysis (FEA) showed reasonable agreement with experimental data, with a 7.11% error in energy absorption (EA). It was highlighted that biodegradable, recyclable, interlocking sandwich-structured composites have potential for advanced, sustainable energy-absorbing structures. Full article

Kenaf (Hibiscus cannabinus) core, an abundant renewable byproduct rich in cellulose and hemicellulose, has emerged as a candidate to replace or supplement peat and coco coir in soilless culture. This review synthesizes the physical, chemical, and biological performance of ground kenaf core and benchmarks it against conventional substrates. Kenaf core exhibits low bulk density (0.06 to 0.15 g cm⁻³), high total porosity (approximately 90%), and substantial plant available water (approximately 42%), supporting root aeration and water supply. Its pH (6.0–7.2) is near optimal for most crops, whereas electrical conductivity (EC) (3.2–4.7 dS m⁻¹) can exceed recommended ranges for salt-sensitive species, which necessitates pre-leaching or blending. Growth studies show comparable shoot and root performance in blends containing 20 to 70% kenaf, with composted kenaf often outperforming raw core. Pure kenaf generally requires more frequent irrigation and may shrink at high proportions. We outline processing variables such as core purity, particle size, composting, and leaching that govern stability and plant response, identify critical data gaps (including standardized EC and pH methods, and long-term shrinkage), and frame a sustainability agenda. Practically, studies to date indicate that pre-leached kenaf core, incorporated at up to about 70% by volume into peat or coir-based blends with structurally stable components such as perlite, can maintain growth and quality for several ornamental and bedding crops under greenhouse and nursery conditions. At the same time, reports of poor performance in some conifers and early suppression in direct-sown vegetables underscore that the suitability of kenaf-based substrates remains crop specific and dependent on material processing and management. Full article

Kenaf (Hibiscus cannabinus) is a versatile fiber crop known for rapid growth and high biomass productivity that is often cultivated in warm-season regions where root-knot nematodes (RKNs) are prevalent. Here, we compared eight kenaf genotypes with Hibiscus acetosella and Hibiscus sabdariffa to evaluate resistance versus susceptibility to five RKN (Meloidogyne spp.) populations in two replicated greenhouse trials. The nematode panel comprised globally dominant species (M. incognita races 2 and 4, M. javanica) and emerging high-impact threats in warm-season systems (M. floridensis and M. enterolobii), which overlap geographically with current and potential kenaf production. Reproduction and galling were quantified using eggs per system, eggs per gram of root, egg masses, gall index, and reproduction factor, and genotypic differences were assessed by nonparametric rank-based tests at α = 0.05. Across nematode species, H. acetosella and H. sabdariffa showed minimal reproduction and galling, whereas most kenaf genotypes were highly susceptible. Susceptibility was most pronounced to M. enterolobii and M. floridensis, and several kenaf lines (‘Whitten’, ‘G 14’, ‘G 32’, ‘Yue 74-3’) had the highest egg counts and near-maximal egg masses and galling. M. incognita race 2 and race 4 produced strong contrasts, with H. acetosella and H. sabdariffa remaining resistant while multiple kenaf lines exhibited heavy reproduction and severe galling. M. javanica followed a similar pattern, with ‘G 32’, ‘Yue 74-3’, ‘Whitten’, ‘G 14’, and ‘74200 I4’ being highly susceptible. These results identify H. acetosella ‘PI 500707’ and H. sabdariffa ‘X17’ as robust donors of RKN resistance and highlight the susceptibility of cultivated kenaf genotypes, underscoring urgent breeding and integrated management needs for kenaf in warm-season production regions. Full article

In this study, the influence of nanochitosan and kenaf fibers on the tensile strength, elastic modulus, and impact strength of polylactic acid (PLA)/natural rubber (Standard Malaysian Rubber, grade 20—SMR20) biocomposites was investigated experimentally using Response Surface Methodology (RSM). The independent variables included the weight percentage of nanochitosan (2, 4, and 6 wt%), kenaf fibers (5, 10, and 15 wt%), and SMR20 natural rubber (10, 20, and 30 wt%). Composite samples were prepared by melt mixing in an internal mixer and subsequently fabricated into test samples using hot compression molding in accordance with relevant standards. Tensile tests were conducted to evaluate tensile strength and elastic modulus, while Charpy impact tests were performed to assess impact strength. The results revealed that increasing nanochitosan content up to 4 wt% enhanced tensile strength, elastic modulus, and impact strength by 39%, 22%, and 27%, respectively; however, further addition (6 wt%) led to a decline in these properties due to nanoparticle agglomeration. Increasing kenaf fiber content to 15 wt% improved tensile strength, elastic modulus, and impact strength by 44%, 26%, and 37%, respectively, demonstrating their effective reinforcing role. The incorporation of SMR20 natural rubber significantly increased impact strength by 59% (at 30 wt%), while causing a reduction of 17% in tensile strength and 20% in elastic modulus, consistent with its elastomeric nature. Furthermore, field emission scanning electron microscopy (FESEM) was employed to examine the dispersion of nanochitosan and kenaf fibers within the PLA/SMR20 matrix, providing insights into the interfacial adhesion and failure mechanisms. The findings highlight the potential of optimizing natural filler and rubber content to tailor the mechanical performance of sustainable PLA-based biocomposites. Full article

Wave Energy Converter (WEC) buoys operate in aggressive marine environments that impose demanding requirements on structural materials, particularly in terms of moisture resistance, mechanical reliability, and long-term durability. Conventional glass fiber reinforced composites meet these performance requirements but raise sustainability concerns due to their high environmental footprint and limited recyclability. This study addresses this challenge by introducing a systematic, application-driven multi-criteria decision-making (MCDM) framework specifically tailored for material selection in marine renewable energy devices. The novelty of this work lies in the integration of marine durability-dominated criteria weighting with sustainability metrics, moving beyond cost-driven selection approaches commonly reported in the literature. Four cellulosic natural fibers, flax, hemp, kenaf, and sisal, are evaluated as reinforcements for polymer composites intended for point-absorber WEC buoy structures, using conventional E-glass as a baseline reference. Ten performance criteria covering mechanical properties, environmental durability, manufacturing feasibility, and sustainability are defined and objectively weighted using the entropy method to minimize subjective bias. Moisture resistance emerges as the most influential criterion with a weight of 0.142, underscoring its role as a primary degradation mechanism in marine environments, while material cost receives the lowest weight of 0.057, reflecting the prioritization of long-term performance over initial cost. The results identify flax as optimal reinforcement, achieving the highest aggregated score of 4.022 by effectively balancing mechanical performance, resistance to marine exposure, and environmental sustainability. This work introduces a novel decision-support tool for the sustainable design of buoy structures using natural fiber-reinforced composites and establishes a foundation for future optimization of such composites in wave energy applications. Full article

Recently, with concern for the environment and the request for sustainable materials, more researchers and manufacturers have focused on the substitute solution of synthetic fiber reinforcement composites in industry applications. Green hybrid composites with natural components can present excellent sustainability, possess superior mechanical behavior, and reduce hazards. Hybridization technology allows new materials to inherit their raw materials’ characteristics and generate new properties. The current study designed novel double-walled shell structures (DS1R4L, DS2R8L, and DS5R12L), containing two thin walls and different numbers of ring and longitudinal stiffeners, as unmanned maritime vehicle (UMV) components. A normal single-walled cylindrical shell was used as a control. These models will be made of hybrid kenaf/flax/glass-fiber-reinforced composites, GKFKG and GFKFG, created in the ANSYS Workbench. The mechanical responses (deformation, stress, and strain characteristics) of models were examined under three loading conditions (end force, end torque, and hydrostatic pressure) to evaluate the influence of both material change and structural configuration. Compared to the single-walled structure, the double-walled configurations display minimized deflection and torsional angle. Moreover, GKFKG-made structures are better than GFKFG-made ones. The research contributes positively to advancing the application of hybrid kenaf/flax/glass-fiber-reinforced composites in UMV structures and promotes the development of green sustainable materials. Full article

Empty fruit bunches (EFBs) and kenaf are two abundant sources of lignocellulosic resource agricultural waste with potential as substrates for mycelium-based composites (MBCs). These composites are lightweight, compostable, low-cost, and suitable for packaging applications. However, their performance is highly dependent on the type of lignocellulosic substrate and the processing conditions applied during production. Despite the promising availability of natural fibers, limited research has focused on the drying process that affects the quality of MBCs. This study investigates the effect of different drying times (12, 18, and 24 h) on the physical and mechanical properties of MBCS produced from EFB and kenaf substrates. Following a 20-day incubation period under controlled conditions, the composites were oven-dried and analyzed for mycelial colonization, density measurement, shrinkage, water loss, shore A hardness, impact resistance, and mold growth. The results demonstrated that a drying time of 24 h yielded the best overall performance. Moisture loss (67.00%) and shrinkage (50.70%) increased with longer drying times (24 h), particularly in kenaf-based composites. Extended drying minimized mold contamination and enhanced the structural integrity of the composites. Overall, EFB-based composites achieved the highest Shore A hardness (44.53 HA). These findings show that optimizing the drying time enhances the durability of MBCs, reinforcing their potential as sustainable, biodegradable alternatives to polystyrene and promoting the development of eco-friendly materials. Full article

Background: Kenaf (Hibiscus cannabinus L.) is an important fiber crop belonging to the genus Hibiscus in the Malvaceae family. Research on its chloroplast genome holds significant importance for deciphering the evolutionary relationships of the Hibiscus species, developing genetic markers, and promoting kenaf (H. cannabinus) genetic breeding. Methods: Based on high-throughput sequencing technology, this study completed the sequencing and assembly of the kenaf (H. cannabinus) chloroplast genome. Results: (1) The kenaf (H. cannabinus) chloroplast genome exhibits a typical circular quadripartite structure with a total length of 163,019 bp, including a large single-copy region (LSC) of 90,467 bp, a small single-copy region (SSC) of 19,486 bp, and a pair of inverted repeat regions (IRa/IRb) of 26,533 bp each. The total GC content is 36.62%, among which, the IR region has the highest GC content (42.61%) and the SSC region the lowest (30.87%). (2) A total of 131 genes were annotated, including 85 mRNAs, 37 tRNAs, 8 rRNAs, and 1 pseudogene. Their functions cover photosynthesis (e.g., pet and atp family genes), self-replication (e.g., rpl, rps, and rpo family genes), and genes with unknown functions (e.g., ycf1 and ycf2). A codon usage bias analysis revealed that the relative synonymous codon usage (RSCU) value of the stop codon UAA is the highest (1.6329), and codons ending with A/U are preferentially used (e.g., GCU for alanine with RSCU = 1.778). (3) A repeat sequence analysis identified various interspersed repeat sequences (predominantly 30~31 bp in length, with a relatively high proportion in the 30~40 bp range, including forward and palindromic types) and simple sequence repeats (cpSSRs). Among them, single-base repeat SSRs account for the highest proportion (e.g., (A)8 and (T)9), and specific SSR primers were designed. (4) A comparative evolutionary analysis indicated that the Ka/Ks ratios (nonsynonymous substitution rate/synonymous substitution rate) of core chloroplast genes (e.g., rps2 and rpoC2) in kenaf (H. cannabinus) are all less than 1 (0.145~0.415), suggesting that they are under purifying selection. The collinearity similarity of chloroplast genomes between kenaf (H. cannabinus) and its closely related species reaches over 99.97%, and the IR region boundaries are relatively conserved. The phylogenetic tree shows that kenaf (H. cannabinus) clusters with closely related Hibiscus species with a 100% bootstrap value, indicating a close genetic relationship. Conclusions: This study provides basic data for the functional analysis of the kenaf (H. cannabinus) chloroplast genome, the phylogeny of Hibiscus, and the utilization of genetic resources. Full article

Hybrid natural/synthetic fiber laminates were examined as a practical process to cut mass, reduce material footprint, and meet structural demands while addressing sustainability targets. Yet direct, like-for-like comparisons generated under a single process and accompanied by durability measurements were limited, leaving design choices uncertain. This study aimed to fabricate and benchmark five representative laminates—C1: flax/epoxy, C2: jute/glass/epoxy, C3: hemp/carbon/epoxy, C4: flax/glass/bio-epoxy, and C5: kenaf/basalt/polyester—under a controlled hot-press schedule with a fixed cavity and verified fiber volume fraction. Panels were characterized using ASTM D3039 tension, ASTM D790 flexure, instrumented impact, 168 h water immersion, and thermogravimetric mass retention. The results were normalized to enable direct multi-criteria comparison, and a model was calibrated to predict tensile strength. C3 delivered the highest strengths (tension ≈ 120 MPa; flexure ≈ 126 MPa), while C5 showed the greatest impact capacity (≈60 kJ/m²). End-of-test water uptake at 168 h was C1 ≈ 3.4%, C2 ≈ 2.6%, C3 ≈ 1.4%, C4 ≈ 2.1%, and C5 ≈ 2.3%. The tensile predictor was fitted to panel means, with an R² of 0.988, and maintained an R² of 0.96 under leave-one-configuration-out testing. These results indicated that carbon-containing hybrids played the most critical roles in terms of stiffness, with kenaf/basalt being most suitable for stiffness-critical components at a similar density, and flax/glass with a bio-resin maximized the sustainability score while maintaining adequate strength. Future research should focus on enhancing specific strength at high renewable content through interface treatments, and extended modeling to improve flexure and impact responses. Full article

Bast fibrous plants are recognized as potential sources of pectin, yet the structural characteristics and functional properties of pectic polysaccharides derived from these plants remain insufficiently investigated. In this study, three pectic polysaccharides (HP, KP, and RP) were isolated from the bast fibers of Cannabis sativa L. (hemp), Hibiscus cannabinus L. (kenaf), and Boehmeria nivea L. (ramie) using an ammonium oxalate solution. Their chemical composition, monosaccharide profile, molecular weight, microstructure, and functional groups were analyzed by spectroscopic and chromatographic techniques. These polysaccharides exhibited remarkable uronic acid content (50.49–61.14%), a relatively low degree of esterification (19.51–34.26%), and high molecular weights ranging from 147.10 to 242.16 kDa. The predominant neutral sugars identified were rhamnose, arabinose, and galactose. Furthermore, HP, KP, and RP demonstrated superior thermal stability, emulsifying properties, water/oil holding capacity, and cholesterol binding ability compared with commercial citrus pectin (CP). They also exhibited stronger radical scavenging activity, with KP showing particularly notable antioxidant performance (IC₅₀ = 1856 and 1485 μg/mL for the DPPH and ABTS assays, respectively). Overall, these findings indicate that bast fibrous plants are promising alternative sources of pectic polysaccharides with favorable antioxidant properties, supporting their potential application as food additives or functional ingredients. Full article

Polyploidization is a rapid breeding strategy for producing new varieties with superior agronomic traits. Kenaf (Hibiscus cannabinus L.), an important fiber crop, exhibits high adaptability to diverse stress conditions. However, comprehensive studies on polyploid induction, screening, and genetic identification in kenaf remain unreported. This study first established an optimal tetraploid induction system for diploid kenaf seeds using colchicine. The results showed that a 4-h treatment with 0.3% colchicine yielded the highest tetraploid induction rate of 37.59%. Compared with diploids, tetraploid plants displayed distinct phenotypic and physiological characteristics: dwarfism with shortened internodal distance, increased stem thickness, larger and thicker leaves with deeper green color and serration, as well as enlarged flowers, capsules, and seeds. Physiologically, tetraploid leaves featured increased chloroplast numbers in guard cells, reduced stomatal density, and larger pollen grains, elevated chlorophyll content. Further analyses revealed that tetraploid kenaf had elevated contents of various trace elements, enhanced photosynthetic efficiency, prolonged growth duration, and superior agronomic traits with higher biomass (54.54% higher fresh weight, 79.17% higher dry weight). These findings confirm the effectiveness of colchicine-induced polyploidization in kenaf, and the obtained tetraploid germplasm provides valuable resources for accelerating the breeding of elite kenaf varieties with improved yield and quality. Full article

This study experimentally investigates the mechanical and dynamic hygrothermal behavior of compressed earth block (CEB) walls subjected to simulated climatic cycles representative of a tropical humid environment. Four formulations were tested: raw soil (D0), soil with kenaf fibers (DF), soil with fibers and cement (DFC), and soil with fibers, cement, and slag (DFCL). Performance was assessed in an instrumented bi-climatic cell, enabling the determination of thermal and hygroscopic attenuation factors and time lags, complemented by standardized uniaxial compression and three-point bending tests. DFCL achieved a compressive strength of about 10 MPa, nearly twice that of DF (~6 MPa), exceeding the threshold required for buildings up to R + 1. Regarding hygrothermal behavior, DFCL exhibited the highest thermal attenuation factor (2.24) and a hygroscopic attenuation factor of 2.05, with corresponding time lags of ~0.9 h (thermal) and ~1.1 h (hygroscopic). These results highlight superior thermal inertia and moisture regulation, well suited to the constraints of tropical humid climates. Overall, the findings confirm the potential of kenaf fiber-reinforced cement–slag stabilized CEBs as a sustainable construction solution, particularly for load-bearing walls in hot and humid regions. In addition to technical performance, DFCL also offers environmental and economic advantages, as the use of local fibers and slag reduces Portland cement consumption and costs, reinforcing its sustainability potential in tropical contexts. Full article

This study investigates the feasibility of kenaf fiber, which is a natural fiber, used as a polymer composite for use in quadcopter arm structures through finite element analysis. The research emphasizes the mechanical performance of various fiber orientations and cross-sectional configurations of the quadcopter arm, focusing on optimizing stress resistance, displacement, and strain characteristics. By relating the relationship between deflection and area moment of inertia of the quadcopter arm, a comparative analysis was conducted for circular hollow tubes, hollow rectangular tubes, and solid rectangular tubes, with the circular hollow tube configuration demonstrating the highest stiffness and minimal deflection. The result from the theoretical calculation and the simulation result of deflection are compared. The study also evaluates the influence of kenaf fiber orientations on the mechanical properties of the composite. Among the seven tested orientations, the sequence 0°, 30°, 45°, 30°, 0° yielded the highest maximum stress (0.3427 MPa), indicating optimal load distribution. Conversely, the 0°, 45°, 0°, 45°, 0° orientation provided the least displacement, making it ideal for high rigidity applications. These findings confirm the potential of kenaf fiber-reinforced polymer as an eco-friendly, lightweight alternative to synthetic fibers for UAV applications, offering a balance of strength, flexibility, and structural stability, and promoting sustainable value in the field of aerospace, as it proves the utilization of waste product into a high-value product. Full article

This study aims to develop high-performance biocomposites for structural applications using kenaf, bagasse, hemp, and softwood fibers bonded with phenol-formaldehyde (PF) and phenol-urea-formaldehyde (PUF) adhesives, commonly used in particleboard manufacturing. A simple, low-cost fiber treatment was applied by adjusting the fiber pH to 11 and 13 using a 33% NaOH solution, following standard protocols to enhance fiber–adhesive interaction. The effects of alkaline treatment on the chemical structure of bagasse, kenaf, and hemp fibers were investigated using Fourier Transform Infrared Spectroscopy (FTIR) and correlated with composite mechanical performance. PF and PUF were applied at 13% (w/w), while polymeric diphenylmethane diisocyanate (pMDI) at 5% (w/w) served as a control for untreated fibers. The fabricated panels were evaluated for mechanical properties; modulus of elasticity (MOE), modulus of rupture (MOR), and internal bond strength (IB), and physical properties such as thickness swelling (TS) and water absorption (WA) after 24 h of immersion. FTIR analysis revealed that treatment at pH 11 increased the intensity of O–H, C–O–C, and C–O bands and led to the disappearance of the C=O band (~1700 cm⁻¹) in all fibers. Bagasse treated at pH 11 showed the most significant spectral changes and the highest IB values with both PF and PUF adhesives, followed by kenaf at pH 13, exceeding EN 312:6 (2010) standards for heavy-duty load-bearing panels in dry conditions. The highest MOE and MOR values were achieved with kenaf at pH 11, meeting EN 312:4 (2010) requirements, followed by bagasse, while softwood and hemp performed less favorably. In terms of thickness swelling, bagasse consistently outperformed all other fibers across pH levels and adhesives, followed by Kenaf and Hemp, surpassing even pMDI-based composites. These results suggest that high-pH treatment enhances the reactivity of PF and PUF adhesives by increasing the nucleophilic character of phenolic rings during polymerization. The performance differences among fibers are also attributed to variations in the aspect ratio and intrinsic structural properties influencing fiber–adhesive interactions under alkaline conditions. Overall, kenaf and bagasse fibers emerge as promising, sustainable alternatives to industrial softwood particles for structural particleboard production. PF and PUF adhesives offer cost-effective and less toxic options compared to pMDI, supporting their use in eco-friendly panel manufacturing. FTIR spectroscopy proved to be a powerful method for identifying structural changes caused by alkaline treatment and provided valuable insights into the resulting mechanical and physical performance of the biocomposites. Full article

The environmental impact of petroleum-based materials in driving climate change has stimulated growing interest in natural lignocellulosic fibers (NLFs) as reinforcements for polymeric matrices. NLFs exhibit specific mechanical properties that, in some cases, rival those of synthetic fibers such as aramid, carbon, and glass. Among the wide variety of NLFs, kenaf has been extensively investigated in applications including textiles, construction, and furniture, owing to its long-established global cultivation. Previous studies have also demonstrated its potential as a reinforcement in polymeric matrices for engineering applications, including ballistic protection. In this context, the present work reports, for the first time, on the tensile and dynamic impact toughness of epoxy matrix composites reinforced with 10, 20, and 30 vol% kenaf fibers. The tensile toughness, defined as the area under the stress–strain curve up to fracture, ranged from 9.36 kJ/m² at 10 vol% to 52.30 kJ/m² at 30 vol% fiber content—representing a three- to tenfold increase compared to the neat epoxy matrix. In Izod impact tests, the composites containing 30 vol% kenaf fibers absorbed 22 times more energy than the neat epoxy, rising from 1.8 to 38.8 kJ/m². On average, the tensile toughness values exceeded those of the corresponding dynamic impact toughness. Scanning electron microscopy revealed the fracture morphology and highlighted the influence of the fibers under both toughness conditions. Full article