Kenaf Fibre Reinforced Cementitious Composites

Increased environmental awareness and the demand for sustainable materials have promoted the use of more renewable and eco-friendly resources like natural fibre as reinforcement in the building industry. Among various types of natural fibres, kenaf has been widely planted in the past few years, however, it hasn’t been extensively used as a construction material. Kenaf bast fibre is a high tensile strength fibre, lightweight and cost-effective, offering a potential alternative for reinforcement in construction applications. To encourage its use, it’s essential to understand how kenaf fibre’s properties affect the performance of cement-based composites. Hence, the effects of KF on the properties of cementitious composites in the fresh and hardened states have been discussed. The current state-of-art of Kenaf Fibre Reinforced Cement Composite (KFRCC) and its different applications are presented for the reader to explore. This review confirmed the improvement of tensile and flexural strengths of cementitious composites with the inclusion of the appropriate content and length of kenaf fibres. However, more studies are necessary to understand the overall impact of kenaf fibres on the compressive strength and durability properties of cementitious composites.

Functional Properties of Kenaf Bast Fibre Anhydride Modification Enhancement with Bionanocarbon in Polymer Nanobiocomposites

The miscibility between hydrophilic biofibre and hydrophobic matrix has been a challenge in developing polymer biocomposite. This study investigated the anhydride modification effect of propionic and succinic anhydrides on Kenaf fibre’s functional properties in vinyl ester bionanocomposites. Bionanocarbon from oil palm shell agricultural wastes enhanced nanofiller properties in the fibre-matrix interface via the resin transfer moulding technique. The succinylated fibre with the addition of the nanofiller in vinyl ester provided great improvement of the tensile, flexural, and impact strengths of 92.47 ± 1.19 MPa, 108.34 ± 1.40 MPa, and 8.94 ± 0.12 kJ m−2, respectively than the propionylated fibre. The physical, morphological, chemical structural, and thermal properties of bionanocomposites containing 3% bionanocarbon loading showed better enhancement properties. This enhancement was associated with the effect of the anhydride modification and the nanofiller’s homogeneity in bionanocarbon-Kenaf fibre-vinyl ester bonding. It appears that Kenaf fibre modified with propionic and succinic anhydrides incorporated with bionanocarbon can be successfully utilised as reinforcing materials in vinyl ester matrix.

Comparison of the Thermal and Electrical Conductivities of Pretreated Kenaf–Polyester Composites

Conductivity of a material is an important physical property that determines its suitability or otherwise in all engineering designs and construction. The aim of this study is to determine the effects of two pretreatment methods viz acetylation and permanganate on the thermal and electrical conductivities of pretreated kenaf bast fibres applied in polyester resin. Fully grown kenaf (hibiscus cannabalis) were manually retted from the stalk, washed, and cut into short fibre lengths of about 10 cm. One portion of the fibres was pretreated with 5%pbw NaOH solution before immersing it in glacial acetic acid and then in acetic anhydride. The second was also pretreated with5%pbw of NaOH before being pretreated with 0.125%of KMnO4. The third portion of fibres was untreated to serve as control. The ground fibre was incorporated into ortho unsaturated polyester rand cast with moulds of dumb-belland square shapes. The electrical conductivity of the composites was deduced by measuring the resistance of the composites using the high voltage insulation tester model 3122 and calculating from equations. The thermal conductivities were determined by analytical method. The results show that chemical pretreatments of fibres by acetylation and permanganate methods have no appreciable effect on the thermal conductivities of composites. Further findings show that the acetylated fibre composites have no effect on the electrical conductivities of the composites. The permanganate pretreated fibre composites however increased the electrical conductivities of the composites significantly.

Isolation of Alkalophilic Pectinolytic Bacteria and their Bio Retting Effect on Kenaf Fiber Compositions

Retting is the most limiting process of high-quality cellulosic kenaf bast fiber production which facilitating the separation of useable fiber from the plants' cell wall matrix. Existing traditional water retting approach confronts ineptitude and eutrophication related complications. Aiming to enhance the kenaf bio-retting process, sixty-seven alkalophilic bacterial colonies were isolated from paddy land soil sediments and kenaf retting water. These isolates were subsequently screened, of that two isolates were selected based on hyper qualitative and quantitative pectinolytic enzymatic measures. 16s rDNA gene sequence analysis revealed that both two strains were closely related to Bacillus pumilus species and designated as KRB56 and KRB22. These strains were applied in augmented non-sterile kenaf tank retting to investigate their kenaf retting efficiency and yielded fiber were analyzed for chemical compositions. Results revealed that, stains KRB56 and KRB22 significantly improve the retting process by degradation of 82.78% and 75.28% non-cellulosic gums, respectively comparing with uninoculated treatment niche (62.12%). Based on un retted raw kenaf fiber maximum fiber bundle weight was reported in MTW with 16.04% material losses, while the SW, and FW treatments showed 24.38%, and 21.03% material losses, respectively. These bacterial treated fiber samples showed thinner, smooth, and cleaner fibers surface morphology by SEM indicates sufficient non cellulosic gums (NCGs) removal comparing with URKF. Moreover, yielded fibers were examined for chemical composition, FTIR, XRD test. Results revealed that compare to un retted and un inoculated kenaf fiber, bacterial treated kenaf fiber increases cellulose portions, and their crystallinity index increases 35.50-41.30 % due to sufficient NCGs removal. This study's findings indicate that isolated alkalophilic bacterial strains KRB56 and KRB22 were effectively to be used as kenaf bio retting agents to produce quality kenaf fiber.

Bacterial Strain for Bast Fiber Crops Degumming and Its Bio-Degumming Technique

The R&D of bio-degumming technology is under a slow progress due to the shortage of proper efficient bacterial strains and processes. A degumming bacterial strain—Pectobacterium wasabiae (PW)—with broad-spectrum degumming abilities was screened out in this study. After the fermentation for 12 h, the residual gum contents of kenaf bast, ramie bast, hemp bast, flax bast, and Apocynum venetum bast were all lower than 15%. This bacterial strain could realize the simultaneous extracellular secretion of pectinase, mannase, and xylanase with the maximum enzyme activity levels of 130.25, 157.58, and 115.24 IU/mL, respectively. The optimal degumming conditions of this bacterial strain were as follows: degumming time of 12 h, bath ratio of 1:10, temperature of 33 ℃, and inoculum size of 2%. After the bio-degumming through this bacterial strain, the COD in wastewater was below 4,000 mg/L, which was over 60% lower than that in boiling-off wastewater generated by chemical degumming. This technology achieves higher efficiency, higher quality, and lower pollution.

The Influence of MMA Esterification on Interfacial Adhesion and Mechanical Properties of Hybrid Kenaf Bast/Glass Fiber Reinforced Unsaturated Polyester Composites

The demand for natural fiber hybrid composites for various applications has increased, which is leading to more research being conducted on natural fiber hybrid composites due to their promising mechanical properties. However, the incompatibility of natural fiber with polymer matrix limits the performance of the natural fiber hybrid composite. In this research work, the mechanical properties and fiber-to-matrix interfacial adhesion were investigated. The efficiency of methyl methacrylate (MMA)-esterification treatments on composites’ final product performance was determined. The composite was prepared using the hand lay-up method with varying kenaf bast fiber (KBF) contents of 10, 15, 20, 25, 30, 35 (weight%) and hybridized with glass fiber (GF) at 5 and 10 (weight%). Unsaturated polyester (UPE) resin and methyl ethyl ketone peroxide (MEKP) were used as binders and catalysts, respectively. Scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR) were used to examine the effects of MMA-esterification treatment on tensile strength and morphology (tensile fracture and characterization of MMA-esterification treatment) of the composite fabricated. The tensile strength of MMA-treated reinforced UPE and hybrid composites are higher than that of untreated composites. As for MMA treatment, 90 min of treatment showed the highest weight percent gain (WPG) and tensile strength of KBF-reinforced UPE composites. It can be concluded that the esterification of MMA on the KBF can lead to better mechanical properties and adhesion between the KFB and the UPE matrix. This research provides a clear reference for developing hybrid natural fibers, thus contributing to the current field of knowledge related to GF composites, specifically in transportation diligences due to their properties of being lightweight, superior, and involving low production cost.

Improved Hydrophobicity of Macroalgae Biopolymer Film Incorporated with Kenaf Derived CNF Using Silane Coupling Agent

Hydrophilic behaviour of carrageenan macroalgae biopolymer, due to hydroxyl groups, has limited its applications, especially for packaging. In this study, macroalgae were reinforced with cellulose nanofibrils (CNFs) isolated from kenaf bast fibres. The macroalgae CNF film was after that treated with silane for hydrophobicity enhancement. The wettability and functional properties of unmodified macroalgae CNF films were compared with silane-modified macroalgae CNF films. Characterisation of the unmodified and modified biopolymers films was investigated. The atomic force microscope (AFM), SEM morphology, tensile properties, water contact angle, and thermal behaviour of the biofilms showed that the incorporation of Kenaf bast CNF remarkably increased the strength, moisture resistance, and thermal stability of the macroalgae biopolymer films. Moreover, the films’ modification using a silane coupling agent further enhanced the strength and thermal stability of the films apart from improved water-resistance of the biopolymer films compared to unmodified films. The morphology and AFM showed good interfacial interaction of the components of the biopolymer films. The modified biopolymer films exhibited significantly improved hydrophobic properties compared to the unmodified films due to the enhanced dispersion resulting from the silane treatment. The improved biopolymer films can potentially be utilised as packaging materials.