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Poly(butylene‐adipate‐co‐terephthalate) (PBAT)/Kenaf fiber composites was prepared by the melt processing technique with various compositions to investigate the general properties. While the Young's modulus of the composite was profoundly improved, the tensile strength and elongation at break exhibited a significant diminished with the incorporation of kenaf fibers due to the poor interfacial adhesion between PBAT and Kenaf fibers. The Halpin‐Tsai model was applied, and the similar behavior of Young's modulus for the composite as compared to experimental results was calculated. The micro‐voids and cavitation were clearly confirmed by morphological observation. Reactive compatibilization with HDI improved the compatibility between PBAT and Kenaf fibers, and the mechanical performance was significantly enhanced due to improved interfacial adhesion. The PBAT/Kenaf composites with a reactive compatibilization showed considerable improvement of storage modulus, G′ in terminal region as well. The stable thermal stability could be also beneficial for thermal processing technique. The addition of Kenaf fiber resulted in a liquid‐like behavior decreasing elasticity of the PBAT/Kenaf composites. The HDI had a profound effect on increasing elasticity with solid‐like behavior resulting in enhancing the G′ and η* of the PBAT/Kenaf fiber composites due to the improved interfacial adhesion as confirmed from the morphological observation. Highlights: Kenaf fiber has a great effect on improvement of the modulus for PBAT/Kenaf compositesThe optimized PBAT/Kenaf composite composition is 96/4 wt% ratio for the compositeHDI is found to be a good compatibilizer for PBAT and Kenaf fiberReactive compatibilization enhances the interfacial adhesion between PBAT and Kenaf fiberThe compatibilized PBAT/Kenaf composites have the better mechanical performance [ABSTRACT FROM AUTHOR]

Highlights Hybrid kenaf/glass fiber reinforced polymer composites have emerged as promising structural materials, garnering significant attention due to their unique blend of natural kenaf fibers and synthetic glass fibers. However, despite their potential, there remains a gap in the comprehensive understanding of their quasi‐static mechanical behavior, creep resistance, and fatigue performance. This paper addresses this gap by presenting recent advancements in studying these key properties of hybrid composites. Studies reveal that the combination of kenaf and glass fibers results in enhanced tensile, flexural, and impact strengths compared to individual fiber composites. Additionally, the hybridization offers improved creep resistance, with the glass fibers reinforcing the polymer matrix against deformation under sustained loads. Furthermore, investigations into fatigue properties demonstrate the resilience of hybrid composites to cyclic loading, contributing to prolonged service life in high‐stress environments. By elucidating the interplay between kenaf and glass fibers, this review underscores the potential of hybrid composites in various structural applications. The synergistic effects between natural and synthetic fibers offer a balance between sustainability, performance, and durability, making hybrid kenaf/glass fiber reinforced polymer composites a compelling choice for industries seeking lightweight, high‐performance materials in which aligns with the sustainable development goals (SDGs) especially on Goal 12. In composite engineering, combining glass and kenaf fibers could cut production costs, yield high‐performance materials, and promote green technology. Substituting part of the glass fiber with kenaf can enhance the strength‐to‐weight ratio and promote greater biodegradability in current synthetic composites. Quasi‐mechanical properties of hybrid kenaf/glass‐based composites was enhanced by optimal stacking sequences, filler addition, and fiber treatment. Failures due to fatigue and creep can be reduced by hybridizing kenaf/glass fiber composites can prevent in polymer composite due to enhance elastic modulus. Enhanced tribological performance of hybrid kenaf/glass‐based composites due to less damage in microstructure via good interlocking of kenaf and glass in matrix. [ABSTRACT FROM AUTHOR]

The rapid advancement of polymer composites, particularly those reinforced with hybrid kenaf, has positioned them as viable structural materials across diverse industries such as automotive, defense, aerospace, marine, construction, and naval. Despite their growing popularity, recent advances in kenaf yarn‐reinforced thermoplastic acrylonitrile butadiene styrene (ABS) composites for structural applications need more comprehensive coverage in the literature. This article addresses this gap by critically examining the influence of quasi‐isotropic stacking orientation on water absorption, flexural strength, and impact properties in kenaf yarn fiber‐reinforced ABS composites. Prepared using hand layup and compression molding techniques, the composites featured varying stacking orientations, including 0°/0°/0°/0°, 0°/90°/0°/90°, −45°/90°/0°/45°, 90°/−45°/0°/45°, 90°/0°/45°/−45°, and 0°/45°/−45°/90° for kenaf yarn reinforced ABS. The findings reveal that the 0°/45°/−45°/90° configuration offers the best overall mechanical properties and water penetration resistance among quasi‐isotropic stacking sequences, exhibiting low water uptake and higher tensile and flexural strengths of 35.3 and 85.4 MPa, respectively, compared to other sequences. This suggests that incorporating ±45° plies contributes to a balanced distribution of mechanical strength and modulus across different directions, making the 0°/45°/−45°/90° configuration ideal for high‐strength structural applications in kenaf yarn/ABS composites. Highlights: Fiber stacking orientation is the key factor affecting the mechanical performance of kenaf‐based composites.Using the hand layup technique, six stacking orientations (0°/0°/0°/0°, 0°/90°/0°/90°, −45°/90°/0°/45°, 90°/−45°/0°/45°, 90°/0°/45°/−45°, and 0°/45°/−45°/90°) were employed to create kenaf fiber‐reinforced ABS composites.A quasi‐isotropic sequence of 0°/45°/−45°/90° allows the least water penetration due to the strategic placement of ±45° plies in the middle layers of composites.0°/45°/−45°/90° configuration offers the best flexural and tensile properties due to better force distribution within the ±45° plies in the middle layers.Under surface morphological analysis, the optimal fiber stacking sequence contributes to fewer voids and fiber pull‐outs. [ABSTRACT FROM AUTHOR]

This study investigated the effect of various stacking sequences on the mechanical and acoustic characteristics of hemp and kenaf fibers reinforced hybrid composites. The mechanical study was done by using universal testing machine and izod imact tester. Further, acoustic study was done by using impendence tube method. Hemp/kenaf/kenaf/hemp hybrid laminates outperformed the other composites in terms of tensile strength, flexural strength and impact strength. In the mono reinforcements, hemp/epoxy composites demonstrated superior mechanical characteristics than the epoxy matrix and kenaf/epoxy composites. However, hybrid composites have superior mechanical behavior compared to pure composites. From the acoustic results revealed that the pure hemp and kenaf/hemp/hemp/kenaf hybrid composites exhibitted highest sound transmission loss level at lowest and highest frequency region. The bestmechanical characteristics of hybrid composites will be suggested for use in automobile door panels. Also, the optimal sound transmission coefficent values signifying their appropriateness for use in applications that encompass many frequency bands. Highlights: Hybridization of kenaf/hemp fibersImproved mechanical properties over the single fiber compositesBetter acoustic properties [ABSTRACT FROM AUTHOR]

BACKGROUND: Kenaf seeds are underutilized kenaf plant by‐products, containing essential nutrients including dietary fiber (DF), which can be potentially utilized as food ingredients. The present study aimed to evaluate the physicochemical characteristics of kenaf seed fiber fractions extracted from kenaf seed. RESULTS: Defatted kenaf seed powder yielded four DF fractions: alkali‐soluble hemicellulose (146.4 g kg−1), calcium‐bound pectin (10.3 g kg−1) and acid‐soluble pectin (25.4 g kg−1) made up the soluble fibre fraction, whereas cellulose (202.2 g kg−1) comprised the insoluble fraction. All fractions were evaluated for their physicochemical properties. The DF fractions contained glucose, mannose, xylose and arabinose, and a small amount of uronic acid (1.2–2.7 g kg−1). The isolated pectin fractions had a low degree of esterification (14–30%). All the isolated DF fractions had high average molecular weights ranging from 0.3 to 4.3 × 106 g mol−1. X‐ray diffractogram analysis revealed that the fractions consisted mainly of an amorphous structure with a relative crystallinity ranging from 31.6% to 44.1%. The Fourier‐transform infrared spectroscopy spectrum of kenaf seed and its DF fractions showed typical absorption of polysaccharides, with the presence of hydroxyl, carboxyl, acetyl and methyl groups. Scanning electron microscopy analysis demonstrated that the raw material with the rigid structure resulted in soluble and insoluble DF fractions with more fragile and fibrous appearances, respectively. The soluble DF demonstrated greater flowability and compressibility than the insoluble fractions. CONCLUSION: These findings provide novel information on the DF fractions of kenaf seeds, which could be used as a potential new DF for the food industry. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

This study presents an innovative approach utilizing Artificial Neural Network (ANN) strategies to evaluate the energy absorption capabilities of eco‐friendly rubber crumb/kenaf composites subjected to low‐velocity impact loads. The primary objectives of this research were to assess the energy absorption characteristics of these sustainable composites, understand their mechanical behavior under the impact, and provide valuable insights into their potential applications. To achieve these objectives, an experimental methodology was employed. Rubber crumb/kenaf composites with varying compositions were prepared, and low‐velocity impact tests were conducted using a drop‐weight impact testing apparatus to assess their energy absorption behavior and these parameters were used as inputs for training the ANN models. The weight percentage of waste tire rubber particle (WTRP), type of impactor and impact energies are considered as input data, whereas the absorbed energy is treated as the output. Through the advanced ANN strategies, accurate predictions of energy absorption performance were achieved for the rubber crumb/kenaf composites. The Levenberg–Marquardt optimisation algorithm with ten neurons and a tangent sigmoid activation function is used to train the ANN model. The trained ANN model is tested on an unseen dataset, different from the training data. It is shown to accurately predict the energy absorption characteristics of WTRP/KRE composites with a maximum error of 4.54%. The results revealed that the composite's energy absorption capabilities were influenced by the ratio of rubber crumb to kenaf, as well as the impact velocity. Additionally, the ANN models demonstrated excellent predictive capabilities, enabling efficient estimation of energy absorption behavior. The significance of these results lies in the potential applications of eco‐friendly rubber crumb/kenaf composites. By understanding their energy absorption characteristics, these composites can be effectively utilized in various industries. For instance, they could be employed in automotive parts manufacturing to enhance occupant safety during low‐velocity impact events. Furthermore, these composites can find applications in sports equipment, protective gear, and other impact‐prone products, contributing to sustainable and environmentally friendly materials. It is believed that by adopting the proposed ANN methodology, the experimentation costs and time can be significantly reduced without compromising the accuracy of the results. The obtained results provide valuable insights into the mechanical behavior of these sustainable composites and open avenues for their implementation in diverse industries where impact resistance is crucial Highlights: Development of sustainable Rubber crumb/kenaf compositesApplication of advanced ANN based predictive assessment of the impact responseParametric study of impactor shape and height of impact is performedThe damage mechanism contributing to energy absorption is micrographically studied [ABSTRACT FROM AUTHOR]

In this study, kenaf natural fibers were coated with acetone‐thinned epoxy resin before compounding with high‐temperature polyethylene terephthalate (PET). Thus, composites of sodium hydroxide treated and epoxy‐resin coated kenaf fibers (KF) reinforced PET (CTKF‐PET) were manufactured using extrusion and compression molding techniques at an optimized 10 wt% constant fiber loading and processing temperatures of 240, 250, and 260°C, and were characterized for mechanical, thermal, and morphological performances. The obtained results showed an optimum processing temperature of 240°C with maximum mechanical and thermal properties with good interfaces between the coated fillers and the matrix, compared to those obtained at 250 and 260°C. Thermogravimetric analysis recorded maximum onset degradation and decomposition temperatures of 338.9 and 381°C with 9.5% and 13% improvements respectively after resin coating which positively impacted the constituent coated composites compared to the uncoated KF. Differential scanning calorimetry glass transition (Tg) and melting temperatures (Tm) for the CKF‐PET composites was maximum at 119.0 and 262.8°C with 2.18% and 2.8% improvements respectively compared to uncoated composites. The overall properties of all coated kenaf‐reinforced PET (CKF‐PET) and coated‐treated (CTKF‐PET) composites were higher with improved morphological properties irrespective of the processing temperature compared to the raw kenaf (KF‐PET) composites. Hence, natural fibers can be treated with resin coating to improve the thermal stabilities of natural fiber engineering plastic composites, and the interfacial adhesion between the coated‐KF and the engineering plastic matrix. The resultant composites are suitable for high‐temperature engineering applications such as the automotive and construction industries. [ABSTRACT FROM AUTHOR]

This research investigates the physical and mechanical properties of hybrid composites made of epoxy reinforced by kenaf and flax natural fibers to investigate the hybridization influences of the composites. Pure and hybrid composites were fabricated using bi‐directional kenaf and flax fabrics at different stacking sequences utilizing the vacuum‐assisted resin infusion method. The pure and hybrid composites' physical properties, such as density, fiber volume fraction (FVF), water absorption capacity, and dimensional stability, were measured. The tests of tensile, flexural, interlaminar shear and fracture toughness (Mode II) were examined to determine the mechanical properties. The results revealed that density remained unchanged for the hybrid compared to pure kenaf/epoxy composites. The tensile, flexural, and interlaminar shear performance of flax/epoxy composite is improved by an increment of kenaf FVF in hybrid composites. The stacking sequence significantly affected the mechanical properties of hybrid composites. The highest tensile strength (59.8 MPa) was obtained for FK2 (alternative sequence of flax and kenaf fibers). However, FK3 (flax fiber located on the outer surfaces) had the highest interlaminar shear strength (12.5 MPa) and fracture toughness (3302.3 J/m2) among all tested hybrid composites. The highest water resistance was achieved for FK5 with the lowest thickness swelling. [ABSTRACT FROM AUTHOR]

In this study, the effect of secondary filler nanographene and primary filler nanoaluminum oxide with kenaf epoxy was investigated. The vacuum bagging process was performed, and a magnetic stirrer was used for blending additives. Water absorption (borewell, distilled, normal, and seawater) and chemical absorption (acid, base, and neutral solution) tests were carried out to evaluate the water absorption, chemical absorption, thickness swelling, and diffusivity of the composite with varying percentages of fillers. The result demonstrates that the addition of 6% primary and 3% secondary filler together, increases the density of the sample by 13.5% and decreases void content by 77%. The addition of secondary filler lowers water absorption in normal water by 1.3% compared to other types of water, as the addition of secondary filler increases the water absorption decreases by 70% in borewell water, 75% in distilled water, 76% in normal water, and 69% in seawater. Thickness swelling of the samples decreases upon the addition of secondary fillers. In acid, the primary and secondary fillers increase the resistance to dissolution. The diffusivity rate of the sample with a combination of fillers 1.3 × 10−5. [ABSTRACT FROM AUTHOR]

Summary: Ester‐linked p‐coumarate (pCA) is a hallmark feature of the secondary cell walls in commelinid monocot plants. It has been shown that pCA groups arise during lignin polymerisation from the participation of monolignol conjugates assembled by p‐coumaroyl‐CoA:monolignol transferase (PMT) enzymes, members of the BAHD superfamily of acyltransferases.Herein, we report that a eudicot species, kenaf (Hibiscus cannabinus), naturally contains p‐coumaroylated lignin in the core tissues of the stems but not in the bast fibres. Moreover, we identified a novel acyltransferase, HcPMT, that shares <30% amino acid identity with known monocot PMT sequences.Recombinant HcPMT showed a preference in enzyme assays for p‐coumaroyl‐CoA and benzoyl‐CoA as acyl donor substrates and sinapyl alcohol as an acyl acceptor. Heterologous expression of HcPMT in hybrid poplar trees led to the incorporation of pCA in lignin, but no improvement in the saccharification potential of the wood.This work illustrates the value in mining diverse plant taxa for new monolignol acyltransferases. Furthermore, the occurrence of pCA outside monocot lineages may represent another example of convergent evolution in lignin structure. This discovery expands textbook views on cell wall biochemistry and provides a new molecular tool for engineering the lignin of biomass feedstock plants. [ABSTRACT FROM AUTHOR]

The current experimental investigation examines the effect of the warp/weft orientation of jute/sisal and flax/kenaf fibers on the static and dynamic mechanical characteristics of intra‐woven hybrid composites. Jute (J), sisal (S), flax (F), and kenaf (K) hybrid woven mats were explicitly designed to keep fibers in the warp and weft directions. Intra‐hybrid‐composites with JJ, JS, SJ, SS, FF, FK, KF, and KK type hybrid woven mats with polypropylene matrix were processed using the compression molding/film stacking method. The tensile and flexural, and the dynamic mechanical behavior was investigated. Utilizing a scanning electron microscope, the fractured surface of tensile test specimens was examined. The results indicate that combining jute with sisal and flax with kenaf improved the mechanical properties of pure sisal and kenaf based composites. Hybridized composites exhibited the maximum increment in tensile strength (5.95% and 31.16%), tensile modulus (4.20% and 66.64%), flexural strength (12.59% and 5.69%), and flexural modulus (47.10% and 19.72%) for JS and FK composites, when compared with unhybridized SS and KK composites, respectively. The fiber hybridization and warp/weft sequence have a substantial effect on the dynamic mechanical performance of woven fiber laminated composites. It was identified that composites of JS and FK possess a higher storage modulus than pure SS and KK based composites, respectively. In addition, at a temperature of 50°C, the storage modulus was improved by 37.63% and 136.63%, for JS and FK hybrid composites, respectively in comparison to the unhybridized SS and KK composites, respectively. [ABSTRACT FROM AUTHOR]

Natural fiber‐based materials are widely accepted in the composite sector as a substitute for synthetic fiber, particularly in structural and semi‐structural implementations in the automotive and aerospace industries, reflecting a recent trend and increased awareness of the importance of sustainable product design. Hand lay‐up was used to create natural fiber bilayer hybrid composites with epoxy matrix reinforcing oil palm empty fruit bunch (EFB) and kenaf fiber matting. The overall effect of this hybridization of the natural fiber and the thermal characterizations were studied experimentally. Both the hybrid combinations kenaf fiber and oil palm EFB were made by maintaining the fiber loading at 50% (weight) and weight ratios at 1:1, 1:4 and 4:1. The Tan delta, loss modulus (E″), storage modulus (E′), and Cole‐Cole plot were found to be useful in investigating dynamic mechanical properties. Dynamic mechanical analysis results like coefficient of performance and Cole‐Cole plot clearly show that hybrid pure kenaf composite has the significant complex modulus because interfacial bond between fiber and matrix is strong. As a result, it has been determined that kenaf fibers have the best mixing ratio for improving the dynamic mechanical properties of these hybrid type composites and can be used for aerospace, automotive, and civil engineering applications requiring high dimensional stability and excellent mechanical properties. The thermal gravimetric analysis data demonstrated that as compared to pure, the kenaf fibers and hybrid oil palm empty fruit bunch composites have the best thermal stability, with the highest beginning and ultimate breakdown temperatures of 200 and 450°C, respectively. [ABSTRACT FROM AUTHOR]

The effect of jute, kenaf, and banana fiber reinforced epoxy hybrid composites with different stacking sequences were fabricated by compression molding techniques. The pure epoxy, pure jute, pure kenaf, pure banana composites are also fabricated for comparison purposes. Tensile, flexural, inter‐laminar shear strengths, and hardness properties of the fabricated composites were investigated. Physical parameters like density, water absorption, and thickness swelling were also examined. From mechanical properties, the results are evident that when compared to hybrid composites pure banana composites have the highest tensile, flexural, interlaminar shear strength and shore D hardness value of 41, 67, 18, and 86 MPa respectively. Also, pure banana composites have better water absorption and thickness swelling percentage of 4% and 1.6%. However, KBJJBK hybrid composites exhibit a maximum tensile strength of 34 MPa, flexural strength of 54 MPa. Further BJKKJB hybrid composites possess the highest hardness value of 87, intralaminar shear strength of 17 MPa and lowest water absorption of 8% and thickness swelling percentage of 2%. Certain pure and hybrid configuration have enhanced mechanical strength, stiffness, and lower water absorption and thickness swelling properties, indicating that they are suitable for automotive structural applications. [ABSTRACT FROM AUTHOR]

In this research, the flexural behavior of lightweight biodegradable sandwich panel consisting of the outer green composite facesheets with polylactic acid (PLA) matrix and natural kenaf and cotton fibers, with five various stacking types of standard cardboard egg boxes cores under three‐point bending loads as an environmentally friendly alternative to conventional synthetic sandwich structures is investigated. The stiffness of this structure in bending is also studied using finite element simulations. The thickest specimen absorbed the most energy during flexural testing, however, the specimens containing two egg boxes inside each other were found to have a higher strength and stiffness. Using finite element method simulations to investigate the influence of composite facesheet thickness on flexural loads, it was found that the amount of the load carried by each sandwich specimen with doubled thickness was increased at least by about 50%. By changing the core's material from cardboard egg box to bamboo/PLA or kenaf‐cotton/PLA egg boxes, stiffness and strength and also the energy absorption were significantly increased. Therefore, it is possible to fabricate composite sandwich structures which are light and biodegradable for green environment and has the potential to replace many plastic products and structures that are used in food packaging and medium loads structures applications. [ABSTRACT FROM AUTHOR]

The current research has produced engineering plastics composite for automotive applications using waste recycled plastic recycled polyethylene terephthalate (RPET) bottles as the matrix and compounded with chemically modified natural kenaf fibers in comparison with virgin polyethylene terephthalate (PET) composites under the same processing conditions. Kenaf fibers were surface modified by alkali and epoxy coating treatment methods. The waste RPET bottles which were mechanically recycled were pulverized using a 5 mm mesh size aperture into flakes and melt‐mixed with 10 wt% of short kenaf fibers in a twin‐screw extruder and compression‐molded at 240°С optimized temperature. Mechanical and thermal analyses were performed on both RPET, virgin PET (VPET), and their constituent kenaf composites. Scanning electron microscopy (SEM) was carried out to assess the composite's morphological characteristics. The results show that both treated (TKF/RPET and TKF/VPET) composites gave higher mechanical properties compared to untreated (KF/RPET and KF/VPET) composites. RPET and its constituent composites show higher impact properties than VPET composites. However, the tensile and flexural strength of VPET composites was higher than that of recycled RPET composites. RPET and VPET showed melting peak temperatures of 252.9°C and 245.8°C respectively. Both treated TKF/RPET and TKF/VPET composites were more thermally stable and decomposed at higher temperatures compared to the untreated composites. The SEM results for both treated composites showed a strong fiber/matrix adhesion with no clear evidence of fiber degradation as compared to untreated composites. It can be concluded that RPET possessed similar thermal properties compared to its virgin counterpart and can serve as a substitute for virgin PET in the composite formulation. [ABSTRACT FROM AUTHOR]

Lignocellulosic hydrolysates contain acetic acid derived from hemicellulose. Acetate released during acid pretreatment interferes with enzymatic saccharification of the biomass and inhibits yeast fermentation, caused by cellular oxidation and stress. This study used alkaline deacetylation prior to acid pretreatment and evaluated its influence on the fermentation performance of Saccharomyces cerevisiae using two different lignocellulosic biomasses, hemp (Cannabis sativa) and kenaf (Hibiscus cannabinus). They are valuable for biofuel production. The maximal acetate removal with minimal sugar loss was obtained with 1% (w/v) NaOH treatment for both biomasses. Deacetylation pretreatment under this condition was effective both in enzymatic saccharification and simultaneous saccharification and fermentation. This resulted in improved ethanol production by xylose-consuming yeast (S. cerevisiae SR8) by removing 4.7 g/L of acetate from hemp and 6.3 g/L from kenaf, thus resulting in the ethanol productivities of 0.79 and 0.67 g/L-h from hemp and kenaf, respectively. This suggests that strategies to overcome acetate inhibition are necessary to efficiently use the lignocellulosic biomass as a source for bioenergy production. [ABSTRACT FROM AUTHOR]

This study evaluates the coagulation performance of kenaf protein fractions (KPFs) comprising of albumin (AlbKP), globulin (GloKP), prolamin (ProKP), and glutenin (GluKP), in the treatment of high (500 NTU), medium (150 NTU), and low (30 NTU) turbidity water. Based on preliminary experimental results, the study focused on GloKP due to it outperforming the other kenaf coagulation products (KCPs) in all water types tested. The influence of GloKP, both as a primary coagulant and coagulant aid to aluminum sulfate (AS) on organic matter removal, was examined. Parametric analysis on turbidity, TSS, pH, dosages, retention time, and KPFs storage time was completed. Results indicated that GloKP could be used both as a primary coagulant and coagulant aid. GloKP had a higher turbidity and solids removal than the AlbKP and other KPFs (ProKP and GluKP). Solution pH greatly influenced the performance of the GloKP, and optimum dosage at pH 2 resulted in the highest organic matter removal. High dosages also resulted in negative mobility of particles and a more stable suspension. When used as a coagulant aid to AS, GloKP was more effective in removing dissolved organic carbon (DOC). Scanning electron microscopy elemental analysis (SEM‐EDAX) and Fourier transform infrared (FT‐IR) spectra showed the structure of the KPFs. SEM‐EDAX indicated the presence of metal cations capable of forming complexes essential for flocs formation. The enhanced floc formation, detailed in this paper, is ascribed to the collective effect of charge neutralization of the AS species and the adsorption and bridging effect of the GloKP, which improves the bonds formed between flocs. The coagulation–flocculation process can be significantly improved using dual coagulants. GloKP was also an excellent alternative to its crude (CrKP) and solvent extract (HxKP) form for removing suspended and dissolved particles from all water types. Practitioner Points: Kenaf protein fractionates can destabilize stable particles.The globulin protein fractionate (GloKP) aggregated the most particles and contained least dissolved organic material.GloKP is pH sensitive with pH 2 reported as best working pH.Coagulant dosage and coagulation mechanism were assessed. [ABSTRACT FROM AUTHOR]

There has been a huge demand in industries for the design and development of bio‐degradable and low‐cost wear resistant composite materials since long. In response to this, the present work includes an exhaustive analysis for the solid particle erosion characteristics of a new class of hybrid polyester composites reinforced with a natural fiber (kenaf) and filled with a construction waste (marble dust) in different proportions. The test trials on the composite samples are conducted using a DUCOM high temperature erosion test rig as per ASTM G76. The experimentation and analysis are conducted as per the L30 model of response surface method (RSM). The results revealed that the incorporation of marble dust enhanced the resistance to erosion wear of the fiber‐polyester composites and among the control factors, the contributions of striking velocity and angle of impingement towards the erosion rate are significant. A predictive model working on the concept of neural networks (ANN) is used for the prediction of erosion rates at different levels and combinations of the significant control factors. The mechanisms of erosion loss are identified from the morphologies of the worn surfaces taken using a scanning electron microscope. [ABSTRACT FROM AUTHOR]

Summary: Tofu was made by substituting kenaf seed (K) with soybean (S) at 100 (positive control), 50%, 40%, 30%, 20%, 10% and 0% (negative control). The results indicated that kenaf seed substitution at all ratios significantly increased the soluble solids and protein content of the milky extracts. The yield, moisture and protein content of the tofu were significantly increased with the increase in kenaf seed substitution, while the lipid content was significantly decreased. The tofu made with kenaf seed substitution of 50%, 40% and 30% had the same protein content (43.76–45.36 g/100 g) with the positive control (45.36 g/100 g), but a significantly higher lipid content (32.00–35.75 g/100 g) than that of the positive control (27.50 g/100 g). The microstructure of the tofu revealed that only the positive control had a honey‐comb structure, whilst the tofu made from kenaf seed‐soybean blends had a pseudo‐honey like structure. Up to 30% of soybean can be added into the kenaf‐based tofu, without any negative effect on the textural and colour properties and, protein content, but significantly improved the essential amino acids content of the kenaf‐based tofu. Therefore, the blend of 70K:30S ratio using 0.5 g% glucono delta‐lactone as a coagulant is recommended to produce kenaf seed‐soybean tofu. [ABSTRACT FROM AUTHOR]

The environmental and social concerns regarding environmental‐friendly materials lead to alternatives in replacing synthetic fibers for natural ones on polymeric composites. This study focused on modeling dynamic mechanical curves of kenaf/polyester composites using response surface methodology (RSM). Composites with three different reinforcement contents (13.5, 22.33, and 36.27 vol%) were produced and subjected to the dynamic mechanical analysis (DMTA). From the experimental DMTA curves, a 3D surface plot using RSM was done. The results showed that the fiber dynamic mechanical behavior and fiber/matrix interface had a low influence on the glass transition temperature but significantly changed the tan δ peak height. On the other hand, the kenaf fibers presented an enormous difference in the elastomeric region. The constrained region (calculated using the tan delta height) increased ~4 times for the composite reinforced with 36.27 vol% when compared to the composite reinforced with 13.5 vol%. The RSM enabled the viscoelastic modeling using different fiber volumes with high reliability and low error (R2 > 0.99). The RSM approach proved to be an intelligent and reliable technique to access a higher range of results, reducing experimental time and cost and keeping statistical significance. Also, the present methodology can be extended to model other properties and/or optimize parameters. [ABSTRACT FROM AUTHOR]

Textile waste is part of the solid waste that should be disposed of due to environmental concerns. Thus, the textile waste composite was proposed as one solution to minimise this problem. However, the properties of the composite produced is one of the issues to tackle to produce high‐quality composite materials. Fibre hybridisation and nanofiller addition have been proved to enhance the properties of polymer composites. Therefore, hybridising textile waste with kenaf fibres was expected to improve the composite's mechanical properties as kenaf fibres have been extensively accepted due to their flexural and tensile strength capabilities. While incorporating carbon nanotubes should enhance the properties of a matrix system. This research aims to analyse the effect of fibre hybridisation and matrix modification on the mechanical properties of kenaf/textile waste composites. The specimens were fabricated using a casting method in a silicon rubber mould. The results show that the hybrid composite had improved tensile, compressive, and impact strength up to 28.57 %, 39.15 %, and 16.33 %, respectively, compared to textile waste composites. Meanwhile, incorporating 1.0 wt. % carbon nanotubes in hybrid composite specimens improved the compressive modulus and impact strength by 108 % and 48.95 % compared to hybrid textile waste composites. [ABSTRACT FROM AUTHOR]

A dual component natural filler system featuring discrete function appears to be suitable for modulating smooth flow of pseudo‐plastic into formulated biodegradable polymer composite. Polypropylene‐co‐ethylene (PPcoE) filled with sago starch and different kenaf powder loadings were compounded using co‐rotating twin‐screw extruder to produce dual component polymer composite. The flow characteristics of the composites were measured using capillary rheometer and Bagley corrections were performed to achieve the true rheological data. In addition, data collected from the twin‐screw extruder were used to calculate the composite apparent rheological value. The flow properties of PPcoE filled with sago starch (PPcoE/sago) exhibited deviation from the common non‐Newtonian thermoplastic flow paths at high shear rates. Interestingly, the addition of kenaf powder into the PPcoE/sago starch blend stabilized the melted composite flow stream. The calculation of interfacial tension revealed that the flow corrections were related to the phase selective localization of kenaf particle, which preferably embedded between the sago particles rather than in the surrounding PPcoE phase thus reducing the effect of sago clustering. At higher extrusion temperature, the extruded composite indicated sign of flow instability due to factors of high amount of kenaf powder loading and the degradation of sago starch and PPcoE chains. [ABSTRACT FROM AUTHOR]

This work aims to optimize the mechanical performance of ramie and kenaf fibers in epoxy composites developed using the hand layup technique. Fiber reinforcement at 0–10 wt% and benzoyl chloride treatment at 0–5 wt% were incorporated with this composites. Taguchi‐based grey relational analysis (GRA) and technique for order preference by similarity to ideal solution (TOPSIS) methods were used to determine the optimized conditions for overall mechanical properties of the developed composites. Optimization techniques concluded that 10 wt% ramie (R)/10 wt% kenaf (K) with 5 wt% benzoyl chloride treatment (T) based epoxy composites observed good mechanical properties with ultimate tensile strength of 37.39 MPa, ultimate flexural strength of 63.53 MPa, and impact strength of 70.36 J/m due to hybridization and the reduction in hydrophilic nature by the surface treatment process. The optimized GRA and TOPSIS combination with 10 wt% R/10 wt% K/5 wt% of T observed reduced water absorption nature with a contact angle of 64.72°. [ABSTRACT FROM AUTHOR]

Salinity is a potential abiotic stress and globally threatens crop productivity. However, the molecular mechanisms underlying salt stress tolerance with respect to cytoplasmic effect, gene expression, and metabolism pathway under salt stress have not yet been reported in isonuclear kenaf genotypes. To fill this knowledge gap, growth, physiological, biochemical, transcriptome, and cytoplasm changes in kenaf cytoplasmic male sterile (CMS) line (P3A) and its iso‐nuclear maintainer line (P3B) under 200 mM sodium chloride (NaCl) stress and control conditions were analyzed. Salt stress significantly reduced leaf soluble protein, soluble sugars, proline, chlorophyll content, antioxidant enzymatic activity, and induced oxidative damage in terms of higher MDA contents in both genotypes. The reduction of these parameters resulted in a reduced plant growth compared with control. However, P3A was relatively more tolerant to salt stress than P3B. This tolerance of P3A was further confirmed by improved physio‐biochemical traits under salt stress conditions. Transcriptome analysis showed that 4256 differentially expressed genes (DEGs) between the two genotypes under salt stress were identified. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis indicated that photosynthesis, photosynthesis antenna‐protein, and plant hormone signal transduction pathways might be associated with the improved NaCl stress tolerance in P3A. Conclusively, P3A cytoplasmic male sterile could be a potential salt‐tolerant material for future breeding program of kenaf and can be used for phytoremediation of salt‐affected soils. These data provide a valuable resource on the cytoplasmic effect of salt‐responsive genes in kenaf and salt stress tolerance in kenaf. [ABSTRACT FROM AUTHOR]

In this work, Bis‐(3‐triethoxysilylpropyl) tetrasulphane was employed for surface modification of silica, ferrite and kenaf fiber filled natural rubber composites using aqueous solvent deposition, dry blending and integral blend methods. The efficiency of each method and the preferred modification method for improving the mechanical performance of natural rubber composites was assessed. The appearance of the Fourier transform infrared spectroscopy peak around 1088 cm−1 for all types of fillers provided evidence that silane interaction had occurred between the fillers and rubber and the formation of siloxane linkages were quantitatively determined by the crosslink density measurement. The surface treatment by dry method for silica and ferrite fillers showed significant improvement of tensile performance at approximately 67% and 34% compared to those with untreated fillers. For kenaf fiber‐filled rubber composites, the surface treatment by aqueous solvent deposition showed the highest tensile improvement of 59% compared to the dry blending and integral blend method. [ABSTRACT FROM AUTHOR]

The dielectric properties of bio‐hybrid composites based on natural Oil Palm Empty Fruit Bunch (OPEFB), montmorillonite (MMT) and organomodified montmorillonite (OMMT) nanoclay reinforced kenaf (KF)/epoxy are reported in this study. The molecular mobility, interfacial adhesion between KF fibers and epoxy resin matrix, and fragility near the glass transition temperature were evaluated using Broadband dielectric spectroscopy over a wide temperature range from 20 to 180°C and a frequency range from 0.1 Hz to 1 MHz. Obtained results indicated different relaxations: the α glass‐rubbery transition and the interfacial polarization between KF/epoxy called Maxwell‐Wagner‐Sillars polarization "MWS(KF/epoxy)" whose amplitude, position and dielectric strength ∆εMWS(kenaf/epoxy) depends on the type of the added nanofillers. ∆εMWS(kenaf/epoxy) decrease for all the measured temperatures while the activation energy Ea of the α‐process and rigidity increase when the nanocharges are introduced. It has been found that the OPEFB, MMT, and OMMT are uniformly distributed in the matrix and act as a link between the KF fibers and the epoxy resin via the formation of new CO and SiOSi bonds. [ABSTRACT FROM AUTHOR]

This study evaluates the thermal and mechanical properties of epoxy hybrid composites reinforced with date palm fiber (DPF) and kenaf fiber (KF) at various fiber loadings. Flexural properties, thermogravimetric analysis (TGA), and dynamic mechanical analysis (DMA) of hybrid composites were reported. The flexural properties revealed the effect of fiber ratio on flexural strength and modulus; a higher kenaf ratio showed a higher flexural modulus. TGA revealed the effect of lignin present in the DPF, which affected the glass transition significantly. In DMA characterization, storage modulus revealed that 7DP3K showed higher modulus in the initial stage and had better glass transition than others. The loss modulus showed that the peak of 7DP3K had higher loss modulus, glass transition at a higher temperature, and wider relaxation period. Damping factor also showed that 7DP3K had peak at a higher temperature. The result showed that KF has positively impacted on DPF to improve the mechanical and thermal properties. The hybrid fibers in epoxy composites were effective in increasing the dynamic mechanical properties and flexural strength ascribed to the improved matrix/fiber bonding. The possible applications of the hybrid composites may be in building industry and automobiles. This study gives directions for further research on comparison of treated hybrid composites with untreated ones. [ABSTRACT FROM AUTHOR]

The application of a nanostructured lipid carrier (NLC) to ultraviolet (UV) filter encapsulation was found to enhance its safe use. In this work, a kenaf seed oil‐NLC (KSO‐NLC) coloaded with 1% diethylamino hydroxybenzoyl hexyl benzoate and 1% ethylhexyl triazone was used as an active ingredient in α‐tocopherol cream to develop a photoprotective prototype. It was then subjected to further analysis to determine its physical properties, storage stability, and cytotoxicity. The ratio of KSO‐NLC to α‐tocopherol cream was optimized based on the sun protection factor (SPF) value using a UV transmittance analyzer. The physical properties of the samples were analyzed, and the amount of α‐tocopherol was quantified by ultra‐high‐performance liquid chromatography. The optimized sample was then evaluated for in vitro antioxidant activities using 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) and 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid assays. Meanwhile, in vitro cytotoxicity was studied on a normal human dermal fibroblast cell line using thiazolyl blue tetrazolium bromide and cell counting kit‐8 assays. The sample of KSO‐NLC to α‐tocopherol cream in a ratio of 1:2 (N3) showed SPF value >50. Besides, the samples showed microbial stability and sustainable α‐tocopherol content upon 12 weeks of storage. The cytotoxicity evaluation of N3 and α‐tocopherol cream (N5) showed >100% cell proliferation, which indicated that there is no side effect on the cell growth, while triggering the cell proliferation with the presence of bioactive compounds. Overall, the findings of the study are promising for the development of new sunscreen formulation with the utilization of KSO‐NLC and palm‐based α‐tocopherol cream. [ABSTRACT FROM AUTHOR]

Kenaf (Hibiscus cannabinus) is an annual fiber crop grown mainly in India and China. This crop is becoming a new bio‐based energy source because of its fast growth rate, excellent CO2 absorption ability, and large productivity per unit area. In this study, we evaluated 10 different cultivars of kenaf for their potential as biomass for cellulosic ethanol production. First, kenaf samples were hydrolyzed using dilute sulfuric acid, which is the most simple and cost‐effective pretreatment method. Next, simultaneous saccharification and fermentation (SSF) of the hydrolysates were performed by wild‐type and engineered xylose‐fermenting yeast strains. The results of compositional analysis of the biomass, the hydrolysates, and the fermented products suggested that ethanol yield and productivity were significantly affected by a type of kenaf cultivars, which was not predictable based on the biomass compositions. Also, the ethanol production was maximized when the xylose fraction was utilized by engineered yeast under the control of pH to avoid acetate inhibition. Considering the sugar compositions and their fermentability, kenaf can be a promising energy‐dedicated crop for cellulosic ethanol production. [ABSTRACT FROM AUTHOR]

The article presents an eco‐friendly approach for the biogenic synthesis of silver nanoparticles (AgNPs) from an aqueous AgNO3 solution by using the Hibiscus cannabinus leaf extract (HCLE) as reducing and stabilizing agent. Reduction of Ag+ ions by HCLE is examined by UV–Visible absorption spectra. The surface plasmon resonance band is observed at 420–460 nm. To recognize the functional group responsible for reduction of Ag+ ions, the HCLE is characterized by Fourier transform infrared spectroscopy. Spherical shaped AgNPs with average particles size 20 nm is confirmed using transmission electron microscopy. The biosynthesized AgNPs displayed distinctive antibacterial activities against both gram positive and gram negative microorganisms. The AgNPs synthesized using HCLE have the potential application in the field of biomedicine. [ABSTRACT FROM AUTHOR]

Summary: Kenaf is an annual crop that is widely cultivated as a source of bast (phloem) fibres, the phytoremediation of heavy metal‐contaminated farmlands and textile‐relevant compounds. Leaf shape played a unique role in kenaf improvement, due to the inheritance as a single locus and the association with fibre development in typical lobed‐leaf varieties. Here we report a high‐quality genome assembly and annotation for var. 'Fuhong 952' with 1078 Mbp genome and 66 004 protein‐coding genes integrating single‐molecule real‐time sequencing, a high‐density genetic map and high‐throughput chromosome conformation capture techniques. Gene mapping assists the identification of a homeobox transcription factor LATE MERISTEM IDENTITY 1 (HcLMI1) gene controlling lobed‐leaf. Virus‐induced gene silencing (VIGS) of HcLMI1 in a lobed‐leaf variety was critical to induce round (entire)‐like leaf formation. Candidate genes involved in cell wall formation were found in quantitative trait loci (QTL) for fibre yield and quality‐related traits. Comparative genomic and transcriptome analyses revealed key genes involved in bast fibre formation, among which there are twice as many cellulose synthase A (CesA) genes due to a recent whole‐genome duplication after divergence from Gossypium. Population genomic analysis showed two recent population bottlenecks in kenaf, suggesting domestication and improvement process have led to an increase in fibre biogenesis and yield. This chromosome‐scale genome provides an important framework and toolkit for sequence‐directed genetic improvement of fibre crops. [ABSTRACT FROM AUTHOR]

Kenaf cellulose fiber was extracted from kenaf locally grown in Thailand as a potential local renewable resource for the cellulose fiber. In this study, the biodegradable polymer composites, poly(butylene succinate) (PBS)/cellulose fiber composites with different types of cellulose were prepared. The kenaf fiber treated with hydrochloric acid (KTH), extracted cellulose fiber (EC), and commercial cellulose fiber (CC) were selected as alternative renewable fillers in the PBS (the biodegradable polymer). Regarding the fiber characteristics, the aspect ratio of the EC (11.5) was found to be higher than that of the CC (6.1). In a similar manner, the EC contained 65.9% crystallinity, which was higher than that of the CC (37.0%) and the KTH (58.9%). Moreover, the EC exhibited higher thermal stability (Td[Max] = 362.9°C) than the CC (Td[Max] = 302.0°C) and the KTH (Td[Max] = 353.8°C). For PBS/cellulose fiber composites, the rheological, tensile, and thermal properties were studied. The rheology results revealed that the addition of the fiber changed the PBS microstructure. The EC fiber dispersion in the PBS seemed to be better than the others; however, the KTH fiber dispersion was poor. The addition of the fiber raised the elastic moduli of the composites by 5‐26%; however, it reduced the tensile strengths (by 14‐53%) and the decomposition temperatures (by 1‐2%). Furthermore, the addition of the fiber slightly affected the crystallization temperatures and melting temperatures of the composites. The yellowness and whiteness of the composites were marginally reduced. The composite with the EC fiber showed a significant improvement in the elastic modulus as compared to the composite with the CC fiber, while the tensile strength and the strain at maximum stress were comparable. Thus, according to the rheological, thermal, and tensile properties of the composites, the EC fiber showed a possibility of using as an alternative reinforcement material from a local renewable resource. [ABSTRACT FROM AUTHOR]

Kenaf core/unsaturated polyester (KC/UP) composites are prepared by mechanical stirrer followed by compression molding. Effect of fiber percentage as well as alkali treatment (NaOH concentration and immersion time) on sound damping performance are analyzed and optimized using three factors and three levels of Box–Behnken experimental design. Flexural properties, heat deflection temperature (HDT), density, lignin content, and morphology are investigated on selected samples. The results show that the optimum condition to produce KC/UP composites is predicted at 54.5% of fiber, 8.1% of NaOH used on alkali treatment, and 2 h fiber immersion on NaOH, giving 5.6% of sound damping/mm. Verifying the model results in 5.1% of sound damping/mm. Despite lower value of verification sample than predicted, this is still between 95% of predicting interval (4.1–7.1%), which is still higher than control sample (3.8%), suggesting model capability to predict the result. Further analysis on selected samples with the highest, mid and lowest sound damping property results in the change of flexural modulus at 38%, −9%, and 28%, respectively, and improvement in HDT (23%, 12%, and 22%). However, the flexural strengths of all selected samples are lower than that of control (−37%, −67%, and −44%). Morphology analysis shows that sample with 45% fiber content is more compact than 30% fiber content, which improves sound damping. [ABSTRACT FROM AUTHOR]

Polylactic acid/rubber/kenaf biocomposites are prepared via melt blending in an internal mixer, followed by compression molding. The effect of different type of rubber is studied based on processing torque, tensile properties, and morphology. Natural rubber (NR) and acrylonitrile butadiene rubber are used, respectively. The content of rubber is fixed at 10 wt%, while kenaf loading has been varied from 0 to 20 phr. Incorporation of NR in biocomposite showed higher processing and stabilization torque compared to acrylonitrile butadiene rubber, However, NR offers higher tensile strength and elongation at break to the biocomposite due to superior properties of NR and strain‐induced crystallization phenomenon. Based on tensile‐fractured morphology, biocomposite with NR shows more tearing effect, which is associated with higher strength. In regard to kenaf loading, the results show that higher kenaf loading causes the tensile properties to decrease and also higher processing torque during mixing. Besides, poor interfacial adhesion is shown by biocomposite with high kenaf loading in the field emission scanning electron microscope micrograph, proven by a smoother fractured surface and more voids due to filler pull‐out. [ABSTRACT FROM AUTHOR]

The demand for natural fibers is increasing worldwide as markets respond to the need to replace nonrenewable sources. Kenaf (Hibiscus cannabinus L.) is a promising biorenewable resource for producing natural fibers. Few studies have investigated the crop when grown at latitudes above 40° and in the U.S. Midwest. The objectives of this study were to assess the influence of management practices on fiber (bast and core lignocellulose) composition, carbon (C), nitrogen (N), and total ash concentration. Cultivars 'Tainung 2' and 'Whitten' were planted in Boone County, IA in 2014 and 2015 at 247,000 or 371,000 seed ha−1, in 38‐ or 76‐cm rows, and fertilized with N at 0, 56, 112, 168, or 224 kg ha−1. Treatments were in a factorial design with four replications in 2 yr. Stem bast and core lignocellulose concentrations, total ash, and C/N ratio were determined at harvest. Variety or interactions of variety with management practices influenced most parameters. Increased N fertilization decreased bast cellulose concentration, but increased core cellulose concentration. Hemicellulose concentration in core was greater than in bast. Ash concentration decreased as N fertilization rate increased and interacted with seeding rate and variety. The implications of these observations are directly related to markets and desired kenaf end‐use products. Variety and management interactions influence kenaf fiber quality, and consequently are important considerations for kenaf producers and processors. [ABSTRACT FROM AUTHOR]

Hybrid composites have shown innumerable benefits to the research communities in terms of environmental friendliness and mechanical properties. This research study presents the mechanical characterization and moisture uptake of kenaf/pineapple leaf fiber‐reinforced polypropylene hybrid composites with several relative fiber ratios. A comparison was also made between nonhybrid and hybrid kenaf/pineapple leaf fiber‐reinforced composites to investigate the hybridization effect. In this work, the composite materials were fabricated via the hot compression technique. Mechanical tests were performed to obtain the tensile, flexural, and Charpy impact properties of nonhybrid and hybrid kenaf/pineapple leaf fiber‐based composites. The water absorption characteristics were then obtained by immersing the composite materials in the water until the saturation point was reached. The findings concluded that the mechanical properties and moisture uptake behaviors of the composites were improved through the hybridization. The hybrid composites with a relative fiber ratio of 25:75 were particularly promising with the improvement of 10.90% in tensile strength; 16.13% in flexural strength; and 6.80% in impact strength in both flatwise and edgewise orientations compared to nonhybrid kenaf‐based composites. Meanwhile, the diffusion coefficient of hybrid composites (25:75) was 56.12% lower than nonhybrid pineapple leaf fiber‐based composites. Thus, the results indeed demonstrated that the balance between mechanical properties and moisture sensitivity can be obtained through the hybridization of kenaf and pineapple leaf fiber in the composite materials. [ABSTRACT FROM AUTHOR]

The type of reinforcement used in polymer composite is one of the main governing parameters to ascertain the performance of a polymer composite. Green composites using fiber mat as reinforcement have shown promising results. In the present study, three different types of kenaf fiber mat (ie, bidirectional, unidirectional, and randomly oriented) have been incorporated with polylactic acid (PLA) for fabrication of green composite laminates through compression molding. Static mechanical characterization (tensile, flexural, and impact) of the developed composites has shown that type of fiber mat affects the mechanical performance of laminated composites markedly. Unidirectional fiber reinforced PLA composite has shown the highest tensile strength in comparison to bidirectional fiber reinforced PLA composite (BDFRPC) and randomly oriented fiber reinforced PLA composite (ROFRPC). BDFRPC has shown better flexural properties whereas ROFRPC achieved higher impact strength. Dynamic mechanical analysis of different kenaf/PLA laminates was performed to investigate the visco‐elastic nature with respect to temperature. Results show that ROFRPC has observed the best results under dynamic loading condition. The morphological study of the fractured surfaces during various testing was performed using scanning electron microscope to investigate mechanisms and reasons of failure of composites. [ABSTRACT FROM AUTHOR]

Natural fibers are very versatile materials; their properties vary with chemical composition to physical structure. The present study deals with the incorporation of different ratios pineapple leaf fiber and kenaf fiber into a phenolic resin to develop hybrid composites. Incorporation of pineapple fibers in kenaf composites are supposed to improve the thermal properties due to higher cellulosic content of pineapple fibers and thermal characterization are studied by thermo‐gravimetric analysis, dynamic mechanical analysis and thermo‐mechanical analysis. Thermo‐gravimetric of 7P3K displayed lowest percentage of weight decomposition and highest residue indicated thermal stability among all the composites. The storage modulus showed decreasing trend with increasing temperature for all the hybrid composites due to constituents of natural fibers. Among all hybrid composites 3P7K hybrid composite showed highest storage modulus and loss modulus at 55.13°C and 101.68°C, respectively. The recorded peak heights of tan δ were minimum for 1P1K (128°C) and maximum for 7P3K hybrid composites (137°C). The Cole–Cole graph determines the heterogeneity of the hybrid composites. Thermo‐mechanical analysis was used to investigate the coefficient of thermal expansion and the mechanical stability of the composites against increasing temperature. Overall results showed that the hybridization of pineapple fibers and kenaf revealed various thermal properties on various fiber ratios. However, 7P3K improves the thermal stability of the obtained material, whereas the 3P7K hybrid composite showed the highest dynamic mechanical properties among all the hybrid composites. 7P3K improved the thermal properties due to presence of cellulosic content whereas 3P7K improved the dynamic mechanical analysis due to better interfacial bonding. POLYM. COMPOS., 40:3814–3822, 2019. © 2019 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Cytoplasmic male sterility (CMS) is widely used in plant breeding and represents a perfect model to understand cyto‐nuclear interactions and pollen development research. Lysine acetylation in proteins is a dynamic and reversible posttranslational modification (PTM) that plays an important roles in diverse cell processes and signaling. However, studies addressing acetylation PTM regarding to anther and pollen development in CMS background are largely lacking. To reveal the possible mechanism of kenaf (Hibiscus cannabinus L.) CMS and pollen development, we performed a label‐free‐based comparative acetylome analysis in kenaf anther of a CMS line and wild‐type (Wt). Using whole transcriptome unigenes of kenaf as the reference genome, we identified a total of 1204 Kac (lysin acetylation) sites on 1110 peptides corresponding to 672 unique proteins. Futher analysis showed 56 out of 672 proteins were differentially acetylated between CMS and Wt line, with 13 and 43 of those characterized up‐ and downregulated, respectively. Thirty‐eight and 82 proteins were detected distinctively acetylated in CMS and Wt lines, respectively. And evaluation of the acetylomic and proteomic results indicated that the most significantly acetylated proteins were not associated with abundant changes at the protein level. Bioinformatics analysis demonstrated that many of these proteins were involved in various biological processes which may play key roles in pollen development, inculding tricarboxylic acid (TCA) cycle and energy metabolism, protein folding, protein metabolism, cell signaling, gene expression regulation. Taken together, our results provide insight into the CMS molecular mechanism and pollen development in kenaf from a protein acetylation perspective. [ABSTRACT FROM AUTHOR]

In this work, three laminated Epoxy composites reinforced with five woven layers of E‐glass fabrics, jute fabrics and kenaf fabrics were characterized by broadband dielectric spectroscopy. The dielectric analysis was performed in temperature range from 20 to 180°C and frequency range from 0.1 Hz to 1 MHz. The Epoxy matrix shows the presence of four relaxation processes, which are attributed to the β relaxation process, α relaxation process, the quasi‐continuous conduction and the dc conduction. In the laminated composite reinforced with the E‐glass fabric, only one additional relaxation process was detected, which was attributed to the interfacial polarization effect known as Maxwell–Wagner–Sillar polarization. However, for the laminated composites reinforced with jute and kenaf fabrics, two additional relaxation processes were observed. While the first one was associated with the water dipoles polarization imputed to the presence of polar water molecules in jute and kenaf fabrics, the second was linked to the interfacial polarization effect. The latter phenomenon was investigated by an analytical study using the Havriliak‐Negami model. The best adhesion between reinforcement and Epoxy matrix was obtained with E‐glass fabrics. This study was supported by the thermal properties using a differential scanning calorimetry. POLYM. COMPOS., 40:2142–2153, 2019. © 2018 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Kenaf (Hibiscus cannabinus L.) is a promising biorenewable resource for producing natural fibers but few studies have investigated the crop when grown in cooler climates, such as the American Midwest. The objectives of this study were to: (i) determine the agricultural practices (row spacing, seed, and N rates) leading to optimal kenaf dry matter (DM) stem and fiber yield in cultivars Tainung 2 and Whitten; (ii) evaluate stem height, basal diameter, and leaf area index (LAI) over the growing season; and (iii) assess the influence of management practices on fiber (bast and core lignocellulose) composition, and-2C, N, and total ash concentration. Kenaf cultivars Tainung 2 and Whitten were planted in Boone County, Iowa,-2in 2014 and 2015 at 247,000 or 371,000 seed ha-1, in 38-cm or 76-cm rows that received 0, 56, 112, 168, or 224 kg N ha-1. Stand density, core:bast fiber ratio, and basal stem diameter were influenced by three-way interactions. Stem height at harvest was influenced by the main effects of row spacing, seeding rate, and N fertilization rate. Nitrogen fertilization did not influence stem DM yield, regardless of application rate. Kenaf is a promising multi-purpose crop that could contribute to the natural fiber marker, as well as diversifying the landscape. Kenaf is well adapted to Iowa and can be produced with a range of management practices. [ABSTRACT FROM AUTHOR]

The aim of this work is to develop a Finite Element Model based on continuum damage mechanics to predict the structural response of Kenaf composite when subjected to high‐velocity impact. The stress–strain response of the Kenaf composite through the fiber direction was simulated to examine prediction accuracy of this simulation approach. A combined elastic‐damage material model, incorporating the 3D Hashin's failure criteria, was implemented into the ABAQUS/Explicit finite element code by user‐defined VUMAT material subroutines. The results from the model predictions were compared with experimental data obtained by SHPB compression testing. The developed Finite Element Model of the full‐scale test presented an accurate prediction of the strain waves in the bars and successfully replicated the structural impact response of Kenaf composite over the range of impact loadings studied. The model also provides a reasonably good agreement between numerical and experimental results on the effect of strain rate on the failure stress and failure strain. POLYM. COMPOS., 40:909–915, 2019. © 2018 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

A novel hybrid composition of sisal fibrils and kenaf fibers has been introduced first time as reinforcement in composite preparation for the environmental friendly high strength electrical insulation applications. Hybrid reinforcement was increased from 10 to 40 wt% in unsaturated polyester resin. The sisal fibril used in this study was extracted from sisal fiber. Alkali treatment was employed and FTIR analysis was done to study its effect on sisal fibrils and kenaf fibers. A positive hybridization effect was observed for the composites. Hybrid composite showed 24 and 18% increase in tensile strength, 30 and 36.4% increase in flexural strength, and 196.3 and 196% increase in impact strength as compared to the composites having same loading of 40 wt% with sisal fibrils and kenaf fibers, respectively. Scanning electron microscopy of the fractured mechanical testing samples was carried out to understand the nature of fibril/fiber/matrix interface. Electrical characterization showed high electrical insulation capability of the hybrid composites. Thermal stability of hybrid composites was also found higher than sisal fibrils and kenaf fibers reinforced composites. A comparative study of properties of sisal fibril/kenaf fiber reinforced hybrid polyester composites with various single and hybrid fiber composites is done. It has been concluded that the developed novel hybrid composite has the potential to replace various existing natural and synthetic fiber composites. POLYM. COMPOS., 40:664–676, 2019. © 2017 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

The hybridization of natural and synthetic fibers in composite materials has gained the attention in the research field due to environmental awareness. Therefore, this study focuses on the effects of fiber stacking configuration on the tensile and quasi‐static penetration of kenaf/glass hybrid fiber metal laminates (FMLs). Kenaf/glass reinforced polypropylene FMLs with two different hybrid stacking configurations were prepared using hot compression process. Non‐hybrid kenaf and glass fiber reinforced metal laminates were also prepared for comparison. The tensile test was conducted according to ASTM E8, while the quasi‐static penetration test was carried out in accordance with ASTM D 6264 using 12.7 and 20 mm hemispherical indenters. The fractured surface of FMLs due to tensile loading was examined using scanning electron microscope, while optical micrograph was used to investigate the failure mechanism of quasi‐statically penetrated laminates. From the results, FMLs with the glass plies at the outer layers of composite (H1) showed a positive hybrid effect as they displayed better tensile and penetration resistance, compared to the non‐hybrid kenaf and glass reinforced FMLs. Furthermore, it could be seen that the overall performance of FMLs decreased as the kenaf content in the laminates further increases for hybrid FML. POLYM. COMPOS., 40:568–577, 2019. © 2017 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

This study was aimed to produce a stable kenaf seed oil‐nanostructured lipid carrier (KSO‐NLC) sunscreen, which can help in the photoprotective effect. The nanostructured lipid carrier (NLC) formulation was optimized and selected based on the results of mean particle size, polydispersity index (PDI), and storage stability of formulas at both chilled (4 ± 2 °C) and room (25 ± 2 °C) temperatures. Uvinul A plus B was added to KSO‐NLC with the optimized formula (80% w/w aqueous phase, 20% w/w lipid phase, and 7% w/w of surfactants with a ratio of 70:15:15 of Tween 20: poloxamer 188: lecithin). The mean particle size distribution (224.73 ± 1.56 nm) and PDI (0.41 ± 0.01) of KSO‐NLC were determined and were found to be stable against storage without creaming or phase separation. The 2,2‐Diphenyl‐1‐picrylhydrazyl (DPPH) radical‐scavenging and 2,2′‐Azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid) diammonium salt (ABTS) radical‐scavenging activities of KSO‐NLC were 5.43 ± 1.00 mg Trolox equiv. g−1 of NLC and 6.70 ± 0.31 mg Trolox equiv. g−1 of NLC, respectively. The Sun Protection Factor (SPF) of KSO‐NLC, 41.38 ± 6.03 with a UVA/UVB ratio 0.64 ± 0.01, suggested a good photoprotective effect. The sustained release of Univul A plus B from KSO‐NLC accompanied by its entrapment efficiency up to 64.09 ± 0.98% and drug loading (DL) of 32.05 ± 0.49% (maximum 50% DL capacity) proved that the degradation of the ultraviolet (UV) filter could be reduced. Therefore, the KSO‐NLC sunscreen was a feasible solution for the photoprotective approach by using unconventional plant seed oil with a significant enhancement (P < 0.05) in many aspects compared to the formula without KSO incorporation. [ABSTRACT FROM AUTHOR]

The interfacial and mechanical properties of nonwoven kenaf fibre (KF) reinforced acrylic based polyester composites fabricated by resin impregnation process were studied. Different types of treatments were applied to KF, i.e. alkali treatment with NaOH at concentration of 6% (at room and elevated temperature of 60°C) and heat treatment at 140°C for 10h. FT‐IR spectral data showed the chemical changes in KF that induced the modification of physical and interfacial characteristics of KF. Alkali treated KF was found to have smaller diameter but higher density. Significant increase in the crystallinity index of treated KF contributed to the improved fibre strength. AFM analysis revealed the exposure of cellulose micro‐fibril network and the increase in the area peak density value of treated KF. Surface energy of KF and surface tension of acrylic resin were obtained through Owens–Wendt–Rabel–Kaelble (OWRK) equation and Du Noüy ring approach, respectively, for the interfacial properties determination. The improved wettability of alkali treated KF was confirmed as higher surface energy of the fibre was recorded exceeding the surface tension of acrylic resin, thereby imparting better flexural properties and dynamic mechanical behavior, but conversely deteriorating the fracture toughness of the reinforced composites. POLYM. COMPOS., 40:E214–E226, 2019. © 2017 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

The molecular mechanisms that underlie drought stress responses in kenaf, an important crop for the production of natural fibers, are poorly understood. To address this issue, we describe here the first iTRAQ‐based comparative proteomic analysis of kenaf seedlings. Plants were divided into the following three treatment groups: Group A, watered normally (control); Group B, not watered for 6 days (drought treatment); and Group C, not watered for 5 days and then rewatered for 1 day (recovery treatment). A total of 5014 proteins were detected, including 4932 (i.e., 98.36%) that were matched to known proteins in a BLAST search. We detected 218, 107, and 348 proteins that were upregulated in Group B compared with Group A, Group C compared with Group A, and Group B compared with Group C, respectively. Additionally, 306, 145, and 231 downregulated proteins were detected during the same comparisons. Seventy differentially expressed proteins were analyzed and classified into 10 categories: photosynthesis, sulfur metabolism, amino sugar and nucleotide sugar metabolism, oxidative phosphorylation, ribosome, fatty acid elongation, thiamine metabolism, tryptophan metabolism, plant–pathogen interaction, and propanoate. Kenaf adapted to stress mainly by improving the metabolism of ATP, regulating photosynthesis according to light intensity, promoting the synthesis of osmoregulators, strengthening ion transport signal transmission, and promoting metabolism and cell stability. This is the first study to examine changes in protein expression in kenaf plants exposed to drought stress. Our results identified key drought‐responsive genes and proteins and may provide useful genetic information for improving kenaf stress resistance. [ABSTRACT FROM AUTHOR]

Mechanical properties of starch‐grafted‐polypropylene/kenaf fibers (KF) composites were investigated and compared to different theoretical models. In this work, the composites were prepared via melt compounding and compression molding processes at different KF loadings, that is, 10, 20, and 30 wt%. Tensile, fracture toughness and fatigue tests were performed. Generally, the mechanical properties increased with increasing kenaf fiber loadings. This is attributed to the good filler‐matrix interactions between KF and starch‐grafted‐polypropylene, as observed by scanning electron microscopy. Tensile properties were modeled using the rule of mixture, the Kelly‐Tyson and the Halpin‐Tsai models. Fatigue data were also modeled using different theoretical models to fit both S–N and normalized S–N curves with simple linear model and Boltzmann sigmoidal function. POLYM. COMPOS., 39:3289–3299, 2018. © 2017 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

The effect of hydrated chromium (III) sulfate ([Cr(H2O)6]2(SO4)3⋅6(H2O)) treated and untreated kenaf (KNF) on the processing torque, functional group, mechanical and morphological properties, water absorption, and thermal stability of KNF filled linear low‐density polyethylene/poly(vinyl alcohol) (LLDPE/PVOH) composites were investigated systematically. It was found that the presence of hydrated chromium (III) sulfate increases the equilibrium torque of treated KNF‐filled LLDPE/PVOH composites. Fourier Transform Infrared (FTIR) Spectroscopy analysis indicated that hydroxyl (–OH) and carbonyl (C = O) group could possibly be involved in the mechanism of adsorption of chromium (III) on KNF surface. The tensile strength and tensile modulus of the treated KNF‐filled LLDPE/PVOH composites were found to have improved. The enhancement in the interfacial adhesion between treated KNF and LLDPE/PVOH is confirmed by the Field Emission Scanning Electron Microscopy (FESEM) analysis. It was observed that with the presence of hydrated chromium (III) sulfate, the water absorption of KNF‐filled LLDPE/PVOH composites was declined. Thermal analysis showed that the treated KNF‐filled LLDPE/PVOH composites exhibited higher thermal stability; as observed from the higher initial and maximum degradation temperatures. J. VINYL ADDIT. TECHNOL., 24:E164–E171, 2018. © 2018 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

During the pultrusion process, there are some parameters that influence the mechanical performance of pultruded composites. The pultruded kenaf composites processing parameter such as pulling speed influenced the pressure and curing behavior of the pultruded composites. The optimal pulling speed leads to the sufficient pressure and temperature and facilitated curing the pultruded composites. Mechanical properties such as tensile strength and modulus, flexural strength and modulus, and compressive strength of kenaf pultruded composites were analyzed in this study and the optimal pulling speed of pultruded composites was determined. The tensile strength and tensile modulus showed the optimal pulling speeds at 0.3 and 0.1 m/min, respectively, while, flexural strength, flexural modulus, and compressive strength were at 0.4, 0.2, and 0.3 m/min, respectively. Scanning electron microscopy images were utilized to study the effect of pulling speed on the morphology of the tensile fracture sample. Fiber wetting, fiber matrix adhesion, the gaps within the samples, and fiber breakages were among the phenomena occurring in the composites. J. VINYL ADDIT. TECHNOL., 24:E13–E20, 2018. © 2016 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]