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In view of no reports on natural fiber reinforced functionalized styrene acrylonitrile composites, this study develops kenaf fiber (KNF) reinforced chemically functionalized styrene acrylonitrile (CF-SAN) composites (KNF/CF-SAN) by extrusion and injection molding. The selected CF-SAN matrix is a chemically functionalized random ter-polymer, with high (10 ± 2%) maleic anhydride functionality and requires higher processing temperature. With respect to CF-SAN, the 10/90, 20/80 and 30/70 KNF/CF-SAN composites show 25%, 46% and 75% higher tensile modulus, 23%, 55% and 78% higher tensile strength, 34%, 66% and 104% higher flexural modulus and 48%, 87% and 125% higher flexural strength. Relative to the dry matrix, the water absorbed composites show higher properties, but relative to the respective dry composites, the water absorbed composites have at least 7% lower tensile strength and at least 20% lower tensile modulus, flexural modulus and flexural strength. SEM and FTIR (ATR-IR) establish that hydrogen bonding and esterification by Palsule process impart CF-SAN/KNF adhesion and bonding in the composites. The composites show thermal stability between KNF reinforcement and CF-SAN matrix upto 295°C. [ABSTRACT FROM AUTHOR]

Implementation of natural fibers like kenaf in composite laminates has been the focus of many researchers. The considerable price of Low-Velocity Impact (LVI) testing, as well as the time constraints imposed by the short duration of this experiment, and prior reports of the obedience of Quasi-Static Indentation (QSI) test findings to LVI test results, have encouraged researchers to employ QSI instead of LVI. This work compares the mechanical characteristics of composite laminates consisting of chopped glass and kenaf fibers as a core and investigates the effect of hybridizing the mentioned chopped fibers as the core of a laminate. Three types of laminates with different core materials were fabricated to do this research. The results showed that among the laminates with the same weight, kenaf core laminate has the highest resistance against indentation and has the best performance in terms of absorbed energy, peak load, and damaged region. Using chopped kenaf fiber instead of chopped glass fiber can increase the absorbed energy and the peak load by 36% and 17%, respectively. Also, hybridizing the mentioned chopped fibers has not fully maximized the properties of the composite laminate during the QSI test. Finally, finite element modelling of the laminates was performed, and the numerical and experimental results were pretty aligned. [ABSTRACT FROM AUTHOR]

In recent years, concerns about environmental pollution have led to the development of natural fiber sandwich structures as alternatives to petroleum-based ones. This paper reviews various studies on sandwich structures composed of non-wood cellulose-nature fibers. These fibers mainly include flax, hemp, jute, kenaf, sisal, coir, and bamboo. The studies are classified based on the type of fibers, the components in which they are used, and experimental tests/numerical investigations. Furthermore, a few suggestions for future research in the field of eco-friendly sandwich structures are made. [ABSTRACT FROM AUTHOR]

The present work deals with the microwave-assisted compression moulding of high-density polyethylene (HDPE)-based composites. In the present work, 20 wt% of reinforcement in the form of kenaf and multi-walled carbon nanotube (MWCNT) was used to fabricate HDPE/kenaf and HDPE/MWCNT polymer composites. The mechanical characterizations of the microwave-processed composites were carried out in terms of uniaxial tensile test with different strain rate, multistep stress relaxation, flexural and impact test. The uniaxial tensile test revealed that the tensile modulus of microwave-processed four-layered HDPE/kenaf polymer composite was 35.2% higher than that of HDPE/MWCNT polymer composite. The HDPE/MWCNT polymer composite showed a minimum of 1.25 GPa and a maximum of 4.7 GPa of elastic modulus when tested at different strain rate. The impact energy absorbed by the HDPE/kenaf polymer composite (1.055 J) was 81.12% higher than the HDPE/MWCNT polymer composite (0.582 J). [ABSTRACT FROM AUTHOR]

Kenaf (Hibiscus cannabinus L.) fiber is being extensively used as a reinforcement material in composites due to its excellent mechanical properties. To use this fiber more efficiently, it is necessary to understand its mechanical properties at micro/nano meter scale. Despite the evidence of some past studies to determine the elastic modulus of kenaf fiber, most of them were performed on fiber bundles. Bundle-based method to find the elastic moduli has some obvious issues of foreign materials being present, incorrect gauge length, and sample diameter due to void spaces. These issues pose as obvious hurdles to determine the elastic modulus accurately. In this study, individual kenaf micro fiber was used to find elastic modulus in the radial direction. The radial elastic modulus of the fiber was characterized by atomic force microscopy-based nanoindentation. To determine the radial elastic modulus from the force versus sample deformation data, the extended Johnson–Kendall–Roberts model was used which considered adhesion force from the fiber surface. The radial elastic modulus of the kenaf fiber was found to be 2.3 GPa. [ABSTRACT FROM AUTHOR]

In the present work, polypropylene (PP)- and polyethylene (PE)-based composites were cured using microwave energy with 15% weight percentage of jute and kenaf fibres. The detailed mechanism of microwave curing of the composites has been discussed with suitable illustrations. The mechanical characterization of the microwave-cured composites was carried out using various tests. The scanning electron microscope (SEM) fractographs were used to study the mechanisms of failure. The ultimate tensile strength of various microwave-cured composites was in the range of 44–50 MPa. The interlaminar shear strength of the PP-based composites was 62% higher than the PE-based composites. The impact energy of the microwave-cured composites was in the range of 18–24 kJ. The mechanical performance of the microwave-cured composites was comparable to the composites obtained through traditional manufacturing routes. [ABSTRACT FROM AUTHOR]

Kenaf core contains a fairly high amount of cellulose and lignin; hence, any attempt to use both components would be beneficial. In this study, kenaf core was used as reinforcement in PP/kenaf core nanocomposites. The core was prepared in two forms: (i) as micron-size reinforcement and (ii) as nanocrystalline cellulose. The bleaching process for nanocrystalline cellulose was conducted at different intensities in order to retain different amounts of lignin in the pulp. Then, the nanocrystalline cellulose was prepared via hydrolysis reaction. Both the micron-size kenaf core pulp and the nanocrystalline cellulose of different bleaching intensity were loaded in the polypropylene matrix with the aid of maleic anhydride grafted polypropylene coupling agent. The mixtures were then hot pressed at 180°C for 8 min to form into standard testing size sample according to standard ASTM D638 (dumbbell shape for tensile test) and D790 (for flexural and impact test). The chemical, mechanical and morphological properties of the composites were evaluated. The results revealed that composites added with unbleached nanocrystalline cellulose (11.48% lignin content) had lowered the tensile and flexural strength. On the contrary, the impact strength was increased when unbleached nanocrystalline cellulose was added. [ABSTRACT FROM AUTHOR]

There has been a vast growth in manufacturing of fiber reinforced plastics by means of liquid composite molding such as resin transfer molding and vacuum-assisted resin transfer molding processes. In these processes, compression of the porous media and pressure of the injected resin result in in-mold forces that need to be determined. Limited information exists regarding the processing parameters and extent of reinforcing potential natural fibers have in polymer matrices. Current study investigates the effect of different variables such as fiber volume fraction, shive content, fiber size, wax content, and resin viscosity on permeability of five different natural fiber mats. Flax fiber with low-, medium-, and high-shive content as well as hemp and kenaf fiber mats was selected for this study and an original experimental device was setup to measure the permeability of the mentioned fiber mats based on different variables. It was found that increasing fiber volume fraction will result in reduction of permeability of all mats. The presence of shive and larger fiber size increased the permeability. Higher wax content lowered the permeability. These competing factors could be used by manufacturers to produce a mat which had optimum permeability while still maintaining acceptable strength. [ABSTRACT FROM AUTHOR]

Nowadays, fiber-reinforced composites have gained attention due to their improved potential for replacing the conventional materials in various applications. Kenaf fiber has been widely used as reinforcement in composites over the past few years which is a most attractive alternative due to its rapid growth at different climatic conditions and ensuring low cost; kenaf fiber has gained some attention to replacing the glass fiber composite and making it purely an eco-friendly composite. However, for enhancing its properties in different applications, an appropriate characterization is very important. Hence, many researches have been conducted in recent years, for the characterization of kenaf fiber and its composites. In this paper, a state-of-the-art review of these characterizations is presented. [ABSTRACT FROM AUTHOR]

Natural fiber-reinforced polymer matrix composites have been increasingly used in automotive and other fields because of their good mechanical properties, low density, excellent damping properties and biodegradability. The objective of this work is to develop and characterize a high-performance lightweight kenaf fiber composite that is processed using unconventional processing methods, wet laid process followed with compression molding process. Kenaf fiber mats produced by wet laid process are stacked with high-density polyethylene films and compression molded into plates from which testing samples are prepared. The effects of fiber length, fiber content, and area density on the tensile properties are investigated. The composite samples with the best tensile properties are also evaluated in its flexural, compression, impact, and fire resistance performance. The processing–structure–property relations of the developed kenaf fiber high-density polyethylene composite are systematically studied, which can be broadly applied to other natural fiber composites. [ABSTRACT FROM AUTHOR]

In this paper, the mechanical performance of resin transfer moulded nonwoven kenaf fibre/epoxy composites in the fibre volume fraction (Vf) range of 0–0.42 was investigated. The effect of the needle-punching direction on the tensile properties of the composites was also investigated. The highest tensile, flexural and fracture properties were attained at a Vf of 0.42. The nonwoven kenaf fibre/epoxy composites were proven to exhibit tensile isotropy. The typical load versus displacement graph and scanning electron microscopy micrographs of the epoxy and nonwoven kenaf fibre/epoxy composites revealed that the energy absorbing events caused by the fibres led to improvements in the fracture toughness. Meanwhile, the micromechanical parameters of the composites were determined by a micromechanics analysis using the Cox–Krenchel model. The analysis proved the applicability of the model for nonwoven kenaf fibre/epoxy composites as the calculated efficiency factors were comparable to the values from previous literatures. [ABSTRACT FROM AUTHOR]

In this work, nonwoven kenaf fibre/epoxy composites were produced by using resin transfer moulding. The effect of kenaf fibre volume fraction on the composites’ tensile properties and Poisson’s ratio was investigated. Experimental results show that highest tensile properties and Poisson’s ratio were attained at volume fraction = 0.42. A simple method has been developed to predict the fibre transverse modulus and has allowed the characterisation of kenaf fibre’s elastic anisotropy. The performance of the Tsai–Pagano model in predicting the composites’ tensile modulus and Poisson’s ratio was compared with the Manera and Cox-Krenchel model. Results showed that the consideration of fibre’s elastic anisotropy in the Tsai–Pagano model yielded a good prediction of both composites’ modulus and Poisson’s ratio. Meanwhile, the Bowyer–Bader model produced a better tensile strength prediction owing to the inclusion of fibre length and orientation factors in the model. [ABSTRACT FROM AUTHOR]

In the present study, six different combinations of pultruded hybrid kenaf/glass composites were fabricated. The number of kenaf and glass rovings was specifically selected to ensure constant local fiber volume fractions in the composites. The volumetric composition of the composites was determined by using a gravimetrically based method. Optical microscopy was used to determine the location of voids. The short-beam test method was used to determine the interlaminar shear strength of the composites, and the failure mode was observed. It was found that the void volume fraction of the composites was increased as a function of the kenaf fiber volume fraction. A linear relationship with high correlation (R2 = 0.95) was established between the two volume fractions. Three types of voids were observed in the core region of the composites (lumen voids, interface voids and impregnation voids). The failure of the samples started with horizontal shear cracks that propagated into the core region, and ultimately the samples failed by a vertical crack. The interlaminar shear strength was found to decrease as a function of the hybrid fiber mixing ratio. [ABSTRACT FROM AUTHOR]

Kenaf fibres of different aspect ratios (L/D = 30 and 160) were melt compounded in an internal mixer with two types of starch-grafted-polypropylene matrices (G906PF and G906PJ) at various loadings, i.e. 10, 20 and 30 wt%. The compound was then compression-moulded into plaques of 1-mm thickness. Thermal, rheological and dynamic mechanical properties of the composite samples were investigated by several techniques involving differential scanning calorimetry, thermogravimetric analysis, melt flow index, Vicat softening point and dynamic mechanical thermal analysis. The results indicated that both thermal and mechanical properties of the composites were remarkably improved by kenaf fibres. Loss modulus and loss factor showed a shift of peak transitions to higher temperatures. Finally, the properties of the investigated composite materials were not affected by the fibre aspect ratio. [ABSTRACT FROM AUTHOR]

The hybridisation of natural fibre with glass fibre provides a method to improve the mechanical properties instead of using the natural fibres alone. This research is focused on the hybridisation of glass/kenaf fibre with the addition of liquid epoxidised natural rubber to enhance the desired mechanical properties of the composite by reducing the synthetic fibre usage and encourage the natural fibre consumption. Liquid epoxidised natural rubber was added to the epoxy matrix in order to improve its mechanical properties whilst E-glass fibre and kenaf bast fibre were used as the reinforcement in the composite. Liquid epoxidised natural rubber (3%) was added as a toughening agent. Two types of kenaf fibre were prepared – untreated and treated with 6% NaOH – whilst the glass fibre was treated using a silane coupling agent. The flexural test, Izod impact test, environmental stress cracking resistance analysis and scanning electron microscopy analysis were performed to determine the effect of fibre treatment and liquid epoxidised natural rubber addition on the mechanical properties of the hybrid fibre-reinforced composite. It was found that the treatment and the addition of liquid epoxidised natural rubber contribute to the increment of the impact strength by 40% whilst the flexural properties recorded a 13% and 15% increment for both flexural strength and flexural modulus, respectively. The environmental stress cracking resistance analysis showed that the composites are more affected in acid medium followed by base medium and then with the control medium (air). The addition of liquid epoxidised natural rubber seems to improve the stability of the samples in the medium initially but tends to decrease rapidly over time due to debonding of the rubber particles. [ABSTRACT FROM AUTHOR]

The disposal problems associated with the conventional plastic have imposed a long-standing quest of developing the degradable material. Indeed, blending of conventional plastic with renewable resources as the base materials is an attempt of imparting some level of biodegradability on the resulting composites. Thus, for this study, the effect of plasticized sago starch (plasticized) incorporation on the properties of low-density polyethylene (LDPE)-reinforced with kenaf core fiber (KCF) was evaluated. The ratio of LDPE/KCF was fixed at 80/20 and blended with the thermoplastic sago starch (TPSS) content ranging from 10 to 40 wt%. The blended samples were characterized by means of mechanical performance, Fourier transform infrared analysis, thermogravimetric and differential scanning calorimetry behavior, water uptake, and morphological properties. The experimental result shows that there is a gradual decrease in tensile strength, modulus, and elongation at break with an increase in TPSS loading. The degree of dispersion and adhesion of TPSS in LDPE/KCF composites revealed by scanning electron micrograph supports the findings of tensile properties. The thermal stability of the composite was clearly improved with the addition of TPSS. However, water uptake and hydrophilic character of the composite system tended to augment as the TPSS imparted to the composites. [ABSTRACT FROM PUBLISHER]

Hybrid composites offer a combination of advantages of constituent components to produce a material with determined properties. In the present work, woven hybrid composite was prepared by hand lay-up method in laminate configuration. Kevlar/kenaf hybrid composites were fabricated with total fibre content of 30% and the ratio of Kevlar/kenaf varies in weight fraction of 78/22, 60/40, 50/50, 26/74, and 32/68, respectively. The Kevlar/epoxy and kenaf/epoxy were also prepared for comparison. The mechanical properties of hybrid, kenaf/epoxy, and Kevlar/epoxy composites were tested. Morphological properties of tensile fracture surface of hybrid composites were studied by scanning electron microscopy. Results have established that the mechanical properties of kenaf-Kevlar hybrid composites are a function of fibre content. The hybrid composites with Kevlar/kenaf (78/22) ratio exhibited better mechanical properties compared to other hybrid composites. This result indicates the potential of Kevlar-kenaf hybrid composite for impact applications. [ABSTRACT FROM AUTHOR]

The effects of kenaf (KNF) loading and 3-aminopropyltriethoxysilane (APTES) on processing torque, tensile properties and morphological properties of KNF-filled polypropylene (PP)/waste tire dust (WTD) composites were investigated. In this research, PP/WTD served as a matrix and KNF as a filler and the composites were prepared using a Thermo Haake Polydrive internal mixer, where different KNF loadings (0, 5, 10, 15 and 20 parts per hundred parts of resin) were used. The results revealed that the stabilization torque and tensile modulus increased with increasing KNF loading but tensile strength and elongation at break were found to decrease. The composites with APTES exhibited higher stabilization torque, tensile strength and tensile modulus but lower elongation at break than composites without APTES. The presence of APTES had enhanced the interfacial adhesion between PP/WTD matrix and KNF, which had resulted in higher tensile strength and modulus of the composites. These findings were supported by the morphological study on the tensile fractured surfaces of the composites. [ABSTRACT FROM PUBLISHER]

In this study, composites were produced using alkali-treated kenaf fibre and recycled polypropylene to improve the interfacial bonding between them. Maleic anhydride grafted polypropylene was used at a ratio of 1:10 to the fibre as a coupling agent. Blends are mixed together by means of a twin screw extruder and test specimens for mechanical testing were prepared through injection moulding machine. Fibre density, tensile property, elemental analysis, structural and morphological changes due to treatment was observed and their effects on the properties of the formulated composites were analyzed. Characterization of the composites was done by the tensile, flexural, impact and melt flow index tests. Thermogravimetric analysis and differential scanning calorimetry analysis were carried out to evaluate the thermal properties of the composites. Experiment showed that best tensile strength (TS) was found at 40% loading of fibre and alkali treatment of fibre enhanced the TS by 57%. Activation energies were calculated through Broido’s equation. It was also found that recycled polypropylene degrades at one stage, while composites degrade at two stages. Incorporating fibres decrease the activation energies of the composites but both coupling agent and treatment of fibres in that case enhance activation energies by 11 kJ mol−1 and 29 kJ mol−1, respectively, in the second stage. Field emission scanning electron microscope of the fractured surface showed that treatment of fibre improves the interfacial bonding between fibres and matrix. Density and water uptake of the composites were also studied in this study. [ABSTRACT FROM AUTHOR]

This article reports the preparation and characterization of newly developed hybrid composites consisting of epoxy resin (EP) matrix, acetylated kenaf bast fiber (AKF) and conducting polyaniline (PANI) nanowires. Initially, the EP/AKF composites were prepared by varying the AKF loading (5–30 wt%). The EP/AKF displayed an optimum tensile strength at 20 wt% AKF loading which was higher than that of untreated kenaf fiber EP composites (EP/UKF). The hybrid composites of EP/AKF/PANI were then prepared by using 20 wt% AKF loading with PANI inclusions from 2 to 14 wt%. The addition of PANI into EP/AKF induced positive electrical properties without considerably sacrificing its mechanical integrity. It was found that the electrical percolation threshold of these hybrid composites was at 11 wt% of PANI loading. PANI inclusions at above the percolation loading resulted in reduction of tensile and flexural strength. Meanwhile, no significant mechanical loss was observed below the threshold. The fracture morphological analysis revealed the occurrences of PANI nanowires pull out from the matrix. The Fourier transform infrared spectroscopy showed that the PANI component still maintained its doped condition inside the EP/20AKF. Water absorption and thermal analysis indicate that the PANI incorporation induced lower water uptakes and greater thermal stability to the EP/20AKF, respectively. [ABSTRACT FROM PUBLISHER]

Kenaf and sisal fibres were selected for the development of natural fibre-reinforced thermoplastic composites because they are in abundance in South Africa. These materials can be used in the building industry, where good mechanical and fire resistance properties are required for structural and non-structural applications. High load bearing, moisture and fire can negatively affect the properties of these composites and decrease their performance. The effect of water glass, maleic anhydride-grafted-polypropylene (MAPP) treatment and fibre loadings on mechanical and thermal properties as well as fire resistance of kenaf and sisal fibre-reinforced polypropylene composites were investigated. The fibre-reinforced polypropylene composites were produced by injection and compression moulding processes. A significant improvement of the tensile strength and modulus of kenaf fibre composites was more pronounced when compared to sisal fibre composites. However, the water glass has a slight negative influence on mechanical properties of fibre/polypropylene matrix composites but showed better fire resistance and thermal properties when compared to the untreated fibre/polypropylene composites. Generally, the impact strength of fibre/polypropylene composites decreased with the addition of MAPP. The low impact strength could be the results of weak interfacial bond strength between the fibre and the matrix. The total heat release was reduced by water glass treatment due to the non-flammable polysilicate coating, while the average mass loss rate was slightly reduced by MAPP. [ABSTRACT FROM AUTHOR]

Kenaf fibre reinforced polyester biocomposites fabricated by hand lay-up technique by using propionic and succinic anhydride-modified kenaf fibres. Chemical structure, mechanical, thermal and morphological properties of kenaf fibres reinforced polyester biocomposites evaluated. The Fourier transform infrared study of modified kenaf fibres carried out to look at changes in functional groups after modification. It confirmed from Fourier transform infrared spectroscopy the variation in positions of functional groups. The mechanical (tensile, flexural and impact) property results revealed that biocomposites with modified kenaf fibres exhibited better properties as compared to untreated kenaf fibres-reinforced polyester biocomposites. Morphological studies show that treated kenaf biocomposites show better fibre/matrix interaction. Thermal analysis results of modified biocomposites exhibited higher initial and final decomposition temperatures. Modified biocomposites display less char residue as compared with unmodified kenaf fibres reinforced polyester composites. [ABSTRACT FROM AUTHOR]

This paper describes how to generate nanofibers from four kinds of polymers, such as polylacticacid, polyamide 6, polyethersulfone, and triacetylcellulose by using an electro spinning method. They are used as surface treatments in the green composites composed of kenaf fibers as the reinforcement and biomass-UP as the matrix, respectively. In order to confirm the effects of the nanofibers, the comparisons of tensile tests are performed. The tensile strengths of specimens with the four kinds of nanofibers were from 23% to 36% higher than those of specimens without the nanofibers. Furthermore, the failure strains of two specimens with the PES and TAC nanofibers increased by 5% and 10% compared with the values without the nanofibers. [ABSTRACT FROM AUTHOR]

Experimental investigations were conducted on kenaf–polypropylene composites manufactured from preformed mats consisting of kenaf and polypropylene fibers in a ratio of 1 : 1 in weight to explore the prospects of annual natural plant fibers as reinforcements for polymer–matrix composites. Surface treatments to the comingled kenaf–polypropylene fiber mats were first carried out using different coupling agents to increase the compatibility of the natural fiber and the polypropylene matrix. Kenaf–polypropylene composite laminates were fabricated from the mats via compression molding. Experimental results indicated that, among the coupling agents chosen, maleated polypropylene was the most effective coupling agent to significantly improve the mechanical performance of the composites. Analyses using Fourier transform infrared spectrometer and scanning electron microscopy revealed that maleated polypropylene was able to promote strong adhesion between the kenaf fibers and the polypropylene matrix at their interfaces. The outcomes of the study indicate that the use of the preformed fiber mats in combination with fiber surface modifications makes it possible to efficiently produce natural fiber reinforced composites with excellent mechanical properties. [ABSTRACT FROM PUBLISHER]

The main objective of this study was to produce ultraviolet curable unsaturated polyester which was then reinforced by variable percentage of kenaf fibre. Unsaturated polyester resin based on palm oil was prepared by the interaction of monoglyceride monomer with maleic anhydride. Gel fraction of the composites increased as the percentage of kenaf fibre was increased up to 10% then decreased with higher kenaf percentage. The effect of kenaf loading on the dimensional stability of unsaturated polyester-reinforced composite showed a significant trend. Morphological study of the composites showed the evidence of the enhancement of compatibility between fibre and polymer. [ABSTRACT FROM AUTHOR]

This work provides variation in mechanical properties such as tensile, flexural and impact strength of hybridized kenaf and pineapple leaf fibre-reinforced high-density polyethylene composite. Two or more natural fibres are hybridized to provide an effective means of designing materials for various service requirements. The composite of kenaf/pineapple leaf fibre high-density polyethylene-based hybrid composite with different weight proportion of fibres were prepared. Total overall fibre loading in the composite was kept at 40%. The hybrid composites prepared were subjected to water immersion for 14 days to see how this concept can affect water uptake. At equal percentage ratio of the fibres, hybridization effect was optimized for tensile and flexural test; however, K6P4 gave the optimum impact strength while K3P7 resulted in the least overall water uptake. Strength and modulus values increased with increase in percentage of pineapple leaf fibre in the composite and the higher aspect ratio of kenaf helped in the dispersion of matrix in the composite. Favorable balance between the inherent advantages and disadvantages of these two fibres complemented each other. While pineapple leaf fibre helped the composite in tensile and flexural properties, kenaf provided impact strength and in reduction of water uptake. Dependence of modulus on the percentage of cellulose in natural fibres was clear. Kenaf and pineapple leaf fibre offered tremendous potential for hybridization. SEM was used to describe this interesting phenomenon. [ABSTRACT FROM PUBLISHER]

In this article, the effect of water glass on the mechanical and thermooxidative properties of kenaf and sisal fibres has been investigated. Single fibres were manually separated from the bundles and immersed in liquid water glass that produced a thick polysilicate coating. The water glass treatment significantly improved the tensile strength and the Young’s modulus of the kenaf and sisal fibres, in relation to the untreated fibres. The improved failure strain of sisal fibre could have occurred because the axial splitting is promoted and the transverse cracking is delayed by the water glass treatment. The reduced thermal resistance of the water glass treated sisal is even more interesting when considering that NaOH treatment (major constituent of water glass) of sisal caused an opposite effect. The thermogravimetric analysis results showed that the water glass treatment strongly affected the chemical composition of the kenaf and sisal fibres. The water glass based thick polysilicate coating was about 40 wt%, which was unusually high. [ABSTRACT FROM PUBLISHER]

The motive of this study is to lessen the dependence on non-degradable plastic packaging by developing alternative material; reinforced poly(lactic acid) (PLA) with kenaf fiber (KF) biocomposite using available plastic processing machineries. For that reason, this study focuses on fabrication of PLA–KF biocomposite using intermeshing co-rotating twin-screw extruder and then injection molded for mechanical characterization. The effect of KF loading from 0 to 20 wt% was studied. No coupling agent was added due to high affinity of PLA and KF and both components are hydrophilic in nature. The average of KF aspect ratio is 30. Tensile properties and flexural properties show similar trend where significant improvement was attained at 20 wt% KF content. Scanning electron micrograph of tensile fracture specimen has revealed the hypothesis of interaction between fiber and matrix which subsequently amplified the tensile properties. It is an interesting finding where the experimental value of tensile modulus was 15% higher than theoretical tensile modulus at 20 wt% KF. Additionally, PLA–KF bicomposite produced, has high specific strength and specific modulus. This could suggest that KF may be incorporated into PLA to reduce mass of the end product and substantially reduce the cost of raw materials. As expected, impact strength however decreases with KF content. [ABSTRACT FROM PUBLISHER]

Hybridized kenaf/PALF-reinforced HDPE composite was produced and characterized. Prepared hybrids were irradiated at various doses of EBI and subsequently with 1%, 2%, and 3% concentrations of vinyltri(2-methoxy ethoxy) silane and TMPTMA as cross-linking agents. The effects of EBI on the mechanical properties of treated and untreated composites were compared. Specimens without cross-linking agents were irradiated using a 2.0 MeV EB accelerator at dose range of 10, 20, 30, 40, 60, 80, and 100 kGy. Thereafter, 10 kGy was selected to irradiate specimens that were prepared with cross-linking agents. Hybrid without the addition of any cross-linking agent showed increase in tensile strength and modulus with increase in radiation dose. Flexural strength, however, showed decline at 80 and 100 kGy. Optimum impact strength was obtained in hybrid prepared without cross-linking agents and at only 10 kGy, while 20 kGy gave superior flexural modulus. Unlike in tensile strength, silane performed better as a cross-linking agent in flexural properties than TMPTMA. Additions of cross-linking agents had less significantly improved the tensile and flexural properties of the hybrid. It was clear that HDPE self-cross-linked by radiation, making silane and TMPTMA less effective. Fractured surfaces of the composites, examined by a scanning electron microscope showed good adhesion between fiber and matrix. [ABSTRACT FROM AUTHOR]

Hybridization, especially where only variant natural lignocelluloses are combined, is fast receiving encouraging attention because it offers a range of properties that may be difficult to obtain with a single kind of reinforcement. In this study, tensile, flexural, and impact properties of hybridized kenaf/PALF-reinforced HDPE composite were studied. Sheets from which tensile, flexural, and impact specimens were cut out were produced from the compression molding of composite pellets and subsequently conditioned in an oven for 21 h at 103°C. The tensile and flexural specimens were tested according to ASTM D638 and ASTM D790 using a 5-kN INSTRON bluehill universal testing machine accordingly. While a notched Izoid impact test was conducted using a 1-J universal pendulum according to ASTM D256. All specimens were prepared at a fiber ratio of 1:1 kenaf:PALF and fiber lengths of 0.25, 0.5, 0.75, and 2 mm; fiber loadings of between 10% and 70% were utilized for the study. About 0.25 mm fiber showed the best tensile and flexural properties with a linear increase in properties up to 60% fiber loading while impact strength showed better property with 0.75 and 2 mm fiber lengths. At 0.25 mm fiber length, tensile strength of 32.24 MPa, flexural strength and modulus of 34.01 MPa and 4114.11 MPa, respectively, were observed at 60% fiber loading. Moduli results of all the composites formulated generally obeyed the ROM. SEM was used to examine the surface of composites produced. Tensile and impact strengths result showed inverse proportionality while flexural strength of the composite generally adhered to the ROM. However, a positive effect was observed in the case of composite’s impact strength in respect of increasing fiber length. Thus, reduction in some mechanical properties of the composite with respect to increasing fiber length is attributed more to fiber entanglement rather than attrition. [ABSTRACT FROM AUTHOR]

Biodegradable composites were prepared by melt-blending technique using 30 wt% kenaf bast fiber (KBF) to reinforce 70 wt% plasticized poly(lactic acid) (PLA). The KBF was treated with various percentages of sodium hydroxide (NaOH), whereas 5% triacetin was used as plasticizer. The effects of the KBF surface treatments on the tensile, flexural, impact strength, and DMA of the biocomposites were investigated. Tensile, flexural, and impact testing results reveal that 4% of NaOH-treated KBF produced composites with optimum tensile strength (62 MPa), flexural strength (67 MPa), and the impact strength (42 kJ/m2). The removal of the lignin from the fiber during the surface treatment caused the increment in the modulus result. This finding is also supported by the dynamic mechanical analysis. The storage modulus of plasticized PLA/treated KBF is higher than the storage modulus of plasticized PLA/untreated KBF which is attributed to the enhancement of the fiber—matrix adhesion. The loss modulus results showed that the Tg of the plasticized composites was shifting to higher temperature, from 55°C for plasticized PLA/untreated KBF to 65°C for plasticized PLA/treated KBF. The increase in Tg shows that the plasticized PLA has low chain mobility when reinforced with treated KBF, indicating better interaction. [ABSTRACT FROM PUBLISHER]

In this study, polyester-kenaf fiber composites were prepared by adding various percentages of kenaf fiber in unsaturated polyester resin and subsequently cross-linked using methyl ethyl ketone peroxide and the accelerator cobalt octanoate. Liquid natural rubber (LNR) (3%) was added as a toughening agent. Kenaf fibers were treated with sodium hydroxide solution to improve the interfacial bonding between the fiber and the matrix. The mechanical properties of the composites were evaluated by impact and flexural testing. Environmental stress cracking resistance (ESCR) of composites in acid and base medium was also studied. Bonding mechanisms were assessed by scanning electron microscope and Fourier transform infrared analysis. It was found that the addition of LNR increased the impact strength and fracture toughness. Alkali fiber treatment was found to provide better impact and flexural strengths to the composites. Measurement of ESCR shows that the composite with acid medium has the fastest diffusion rate, followed by that with base medium, and then without medium. [ABSTRACT FROM AUTHOR]

In this study, mechanical properties such as tensile characteristics, flexural characteristics, impact strengths, and hardness of kenaf/phenol-formaldehyde (PF), fiberfrax/PF, and kenaf/fiberfrax hybrid PF composites have been investigated as a function of fiber loading. Composite samples were prepared by mixing the fibers and resin in a mixing chamber for 5 min. The composite sheets were prepared by pressing fiber-resin material in a steel mold at 120°C for 30 min at 10MPa pressure. The test samples were cut from the composite sheets. At least five specimens were tested and mean value was taken for each composite according to ASTM standards. The reinforcing effects of kenaf and fiberfrax fibers were evaluated at various fiber loadings, that is, 19, 28, 36, 43, 52, and 62 vol.%. The hybrid effect of kenaf and fiberfrax fiber on the tensile, flexural, impact strengths, and hardness was also investigated for various ratios of kenaf/fiberfrax fiber loadings ranging between 1 : 0 and 0 : 1. Total fiber loading of the hybrid composites was 43 vol.%. The tensile, flexural strength, and hardness of the composites increased with increasing fiber loading up to 43 vol.% and decreased above this value for kenaf/PF composites. Impact strength of kenaf/PF composite showed a trend of increase with increasing fiber loading. The tensile and flexural strength of fiberfrax/ PF composites increased by incorporation of fiberfrax fiber up to 36 vol.% and decreased beyond this value. However, the maximum impact strength and hardness were obtained for 52 vol.% fiberfrax fiber loading. The tensile, flexural, and impact strength values of fiberfrax/PF composites were found to be lower compared to kenaf/PF composites. With addition of fiberfrax fiber, the tensile, flexural, and impact strengths of the kenaf/fiberfrax hybrid PF composites decreased linearly and the hardness of the composite increased. The maximum hardness value was obtained for 0.25 : 0.75 kenaf/fiberfrax ratio. [ABSTRACT FROM AUTHOR]

The composite material based on whole stem kenaf fiber (WSK) and Ecoflex (biodegradable thermoplastic) were prepared by melt blending technique and characterized. The composites were prepared using different fiber loadings and the fiber was treated with various concentrations of NaOH solution by soaking for 3 h. The compounding of composite were carried out at different fiber loadings (10%, 20%, 30%, 40%, 50%) using Brabender internal mixer at 130°C for 10 min. The composites were then pressed using compression molding to produce biodegradable kenaf/Ecoflex sheets. The effects of kenaf fiber loading and NaOH treatment of WSK fiber surface on mechanical properties was examined. The results showed that 40% fiber loading improved the tensile strength properties and WSK fiber treated with 4% NaOH was found to enhance tensile and flexural properties compared with untreated fiber. The FTIR characterization showed that alkali treatment removes hemicellulose and lignin from WSK kenaf fiber surface. [ABSTRACT FROM AUTHOR]

In this article, the mechanical, morphological, and dynamic-mechanical properties of the blends of PLA and kenaf bast short fiber were investigated. The composites, with different fiber loading and triacetin content, were prepared by melt blending techniques using a Brabender internal mixer at 60 rpm and 170°C for 10 min and their properties were examined. Pure PLA was used as a reference for the biocomposite samples. Triacetin was used as a plasticizer for PLA and PLA/kenaf composites in order to study the improvement in tensile properties. The tensile strength and stiffness of unplasticized biocomposite materials decreased with the addition of kenaf bast fibers but improved with the addition of triacetin. The optimum fiber loading was 30wt% kenaf fibers in the PLA matrix with the addition of 5% triacetin. The dynamic mechanical analyses showed that triacetin improved the thermal stability of the biocomposites. The triacetin increased the storage modulus and gave a lower softening temperature for plasticized biocomposites. The micrographs of the tensile specimens and their fractured surfaces, which were examined by scanning electron microscopy, demonstrated that better adhesion between the fibers and the matrix was achieved with the addition of the plasticizer. [ABSTRACT FROM AUTHOR]

A series of tensile tests were conducted on a Lloyd LRX tensile testing machine for numerous natural fibers deemed potential candidates for development in composite applications. The tensile tests were conducted on the fibers jute, kenaf, flax, abaca, sisal, hemp, and coir for samples exposed to moisture conditions of (1) room temperature and humidity, (2) 65% moisture content, (3) 90% moisture content, and (4) soaked fiber. These seven fibers were then tested for the four conditions and the mechanical properties of tensile strength, tensile strain to failure, and Young's modulus were calculated for the results. These results were then compared and verified with those from the literature, with some of the fibers showing distinctly promising potential. Additionally, a study on the effect of alkalization using 3% NaOH solution was carried out on flax, kenaf, abaca, and sisal to observe impact that this common fiber pre-treatment process has on fiber mechanical properties. The result of the investigation indicated that over treatment of natural fibers using NaOH could have a negative effect on the base fiber properties. It is consequently apparent that a treatment time of less than 10 min is sufficient to remove hemicelluloses and to give the optimum effect. [ABSTRACT FROM AUTHOR]

Hybrid composite of thermoplastic natural rubber (TPNR) reinforced with Hibiscus cannabinus, L fiber (kenaf fiber: KF) and short glass fiber (GF) were prepared via melt blending method using internal mixer, at various temperatures, speed and time. TPNR matrix is a blend of polypropylene (PP), liquid natural rubber (LNR) and natural rubber (NR) at a ratio of 70: 10: 20. Processing parameters were determined from the tensile strength based on fiber content with 50: 50 ratios of GF and KF. Using the optimum processing parameters, tensile test was carried out for reinforced TPNR-KF-GF hybrid composites (0-20% by volume), with and without addition of silane coupling agent and maleic anhydride grafted polypropylene (MAPP). The result of tensile strength has shown that the increasing in kenaf fiber content substantially reduced the tensile strength and modulus. Scanning electron microscopy (SEM) has shown that the composite, with coupling agent or compatibilizer, promotes better fiber-matrix interaction. [ABSTRACT FROM AUTHOR]

Kenaf fiber (KF) based thermoplastic natural rubber (TPNR) composite was produced by melt blending with polypropylene (PP). Kenaf fiber (15% by volume) and TPNR were mixed in as Haake 600p internal mixer. The fracture behavior of the TPNR matrix and of TPNR--kenaf (with and without maleic anhydride grafted polypropylene, MAPP) composites was evaluated using the essential work of fracture (EWF) method and double edge notched tensile (DENT) specimens. Various ligament lengths were employed ranging from 4 to 12mm. The strain rate was fixed at 2 mm/min. The specific work of fracture (we) and plastic work (ßwp) showed the highest energy for TPNR that corresponds to its ductility and allows the application of the EWF approach. It was found that the presence of kenaf fibers and MAPP reduced the toughness of TPNR and changed the ductile fracture to brittle behavior. SEM observation revealed that energy absorption mechanisms include matrix deformation, fiber pullout, and fiber breakage. Acoustic emission (AE) was employed to analyze the failure processes further. The signals emitted by composites were substantially higher than that of the TPNR matrix, reflecting that also the failure mechanisms were affected by the fibers incorporated. [ABSTRACT FROM AUTHOR]

An instrumented Izod test was used to investigate the effects of fiber content, coupling agent, and temperature on the impact performance of kenaf fiber reinforced polypropylene (PP). Composites containing 0-60% (by weight) kenaf fiber and 0 or 2% maleated polypropylene (MAPP) and PP/wood flour composites were tested at room temperature and between -50°C and +50°C. At room temperature, kenaf greatly reduced energy to maximum load (EML) in reversed notch tests but had little effect in notched tests. MAPP improved all test values. At -25°C, PP specimens changed from ductile to brittle. Kenaf composites containing MAPP consistently yielded higher EML values than did both unfilled PP specimens and wood flour composites in notched impact tests, over the temperature range investigated. The EML values for kenaf composites were about half those for unfilled PP specimens in reversed notch tests at room temperature, but performance was similar at low temperatures. [ABSTRACT FROM AUTHOR]