Search

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]

Natural fibre-reinforced composites have been developed by researchers and industries as a solution to reduce the use of synthetic fibres. Kenaf fibre is one of the most abundant natural fibres in Indonesia. This study aimed to obtain the mechanical and thermal properties of kenaf fibre-reinforced epoxy laminated composites fabricated using a vacuum-assisted resin infusion method. The alkaline-treated fibres were arranged in the orientations 0°/0°/0°/0° and 0°/90°/0°/90°. Density measurements, mechanical tests, and thermogravimetric analysis were carried out on the epoxy and the composites. The results of the mechanical testing showed that the tensile, flexural, and compression strengths of the kenaf fibre-reinforced epoxy composites with a 0°/0°/0°/0° fibre orientation were higher than those of the composites with a 0°/90°/0°/90° fibre orientation, with values of (96.61 ± 10.18) MPa, (131.01 ± 6.60) MPa, and (71.96 ± 5.50) MPa, respectively. Scanning electron microscope observations showed that the composites had good fibre-matrix adhesion. The thermal stability of the epoxy was enhanced from 557 °C to 571 °C by incorporating kenaf fibre with 0°/0°/0°/0° orientation. With reference to the Indonesian National Standard 01-4449–2006, the two composites could be classified as T2 45 High Density Fibreboard. [ABSTRACT FROM AUTHOR]

Natural fiber reinforced polymeric composites perform poor in mechanical and thermal properties at elevated temperatures due to the cellulose and hemicellulose contents of natural fiber start degrading at elevated temperature. In this research work, flame retardancy and thermal stability of treated and untreated kenaf fiber reinforced epoxy composites have been experimentally investigated and reported. Two composite laminates, one with 6 % NaOH Alkali treated and another with untreated woven kenaf mats, were fabricated by hand lay-up technique followed by compression molding with 40 % fiber weight fractions. Flame retardancy test and various thermal characteristics studies such as thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), heat deflection temperature (HDT), and morphological analysis via scanning electron microscopy (SEM) tests were carried out. The results showed that alkali treated kenaf fiber composite achieved V0 fire retardancy grade. The major weight losses, 86 % and 75.5 % for untreated and treated composites respectively were recorded between 300 °C and 450 °C. 13.6 % increase in HDT was noted for treated composite with 0.25 mm deflection at 0.45 MPa pressure condition. Thus the composite laminate with 6 % NaOH alkali-treated kenaf fiber achieved the best thermal stability with less degradation which is more suitable for automobile and aerospace applications. [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]

The application of natural fibers is increasing rapidly in the polymer-based composites. This study investigates manufacturing and characterization of polypropylene (PP) based composites reinforced with three different natural fibers: jute, kenaf, and pineapple leaf fiber (PALF). In each case, the fiber weight percentages were varied by 30 wt.%, 35 wt.%, and 40 wt.%. Mechanical properties such as tensile, flexural, and impact strengths were determined by following the relevant standards. Fourier transform infrared (FTIR) spectroscopy was employed to identify the chemical interactions between the fiber and the PP matrix material. Tensile strength and Izod impact strength of the composites significantly increased for all the composites with different fiber contents when compared to the pure PP matrix. The tensile moduli of the composites were compared to the values obtained from two theoretical models based on the modified "rule of mixtures" method. Results from the modelling agreed well with the experimental results. Tensile strength (ranging from 43 to 58 MPa), flexural strength (ranging from 53 to 67 MPa), and impact strength (ranging from 25 to 46 kJ/m2) of the composites significantly increased for all the composites with different fiber contents when compared to the pure PP matrix having tensile strength of 36 MPa, flexural strength of 53 Mpa, and impact strength of 22 kJ/m2. Furthermore, an improvement in flexural strength but not highly significant was found for majority of the composites. Overall, PALF-PP displayed better mechanical properties among the composites due to the high tensile strength of PALF. In most of the cases, T98 (degradation temperature at 98% weight loss) of the composite samples was higher (532–544 °C) than that of 100% PP (500 °C) matrix. Fractured surfaces of the composites were observed in a scanning electron microscope (SEM) and analyses were made in terms of fiber matrix interaction. This comparison will help the researcher to select any of the natural fiber for fiber-based reinforced composites according to the requirement of the final product. [ABSTRACT FROM AUTHOR]

The use of composite materials with natural fiber reinforcement (CMNFR) has experienced rapid development in the automotive industry to apply synthetic materials that are expensive and not environmentally friendly. Biocomposite is a composite consisting of a polymer matrix and natural fiber reinforcement. Natural fiber materials are used as a substitute for conventional non-renewable reinforcing materials. This study uses the vacuum-assisted resin infusion (VARI) process to fabricate composites using woven kenaf and jute from natural fiber. The Taguchi experimental design method with L273 as an orthogonal array matrix was used in this research to obtain the optimum CMNFR fabrication parameters. Response Surface Methodology is used to obtain the optimal response value based on microstructural analysis. The factors used were NaOH treatment (4, 6, 8 wt%), water absorption test (6, 12, 24 hours), and fiber type (KF, JF, KF-JF). The study's results found a combination of optimization of CMNFR manufacturing parameters using RSM, namely, A1B1C2 with a mean material strength of 0.241 J/mm2 (impact strength) and a combination of A1B3C1 parameters with a mean material strength of 94.8650 MPa (flexural strength). It was also found that the presence of contaminants and voids harmed the mechanical properties. [ABSTRACT FROM AUTHOR]

Natural fiber reinforced hybrid polymer composites have attracted many researchers’ attention compared to synthetic fiber composites due to their better mechanical properties. Besides being inexpensive, natural fibers are eco-friendly. In the literature, kenaf fiber has shown an enormous future for its suitability in technical applications. The present studies explore the mechanical properties of kenaf and kapok fiber reinforced hybrid polyester composites. The composites are prepared by simple hand lay-up technique. The test specimens were prepared according to ASTM standards and the tensile, bending, and impact strength was evaluated experimentally. The result shows that composite with equal contribution of kenaf and kapok fiber reinforcement has tensile and impact strength of 25.25 ± 4.29 MPa and 46.65 ± 0.01 KJ/m² respectively. As the kapok fiber content increases the bending strength and bending modulus of composites decrease. The results show that the tensile and impact strength of hybrid composites has improved considerably compared to neat kapok composites. Scanning electron microscopy (SEM) was carried out to examine the fractured surfaces of tested specimens. [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]

Ramie fiber reinforced thermoplastic and thermoset polymer composites Ramie is the toughest bast fiber that yielded its fiber from the bark of the canes, which supplies exceptional raw material for blending with natural and synthetic fibers with higher luster, tenacity, brightness, and resistance to light, heat, alkali, and acid (Kiruthika [40]; Rehman et al. [74]). Hemp fiber reinforced thermoplastic and thermoset polymer composites Hemp fiber is another branch of bast fibers that are extremely used in the development of bio-based composites to prevail over the use of synthetic-based composite materials in the diversified application areas (Aisyah et al. [1]; Dixit et al. [18]). Kenaf fiber reinforced thermoplastic and thermoset polymer composites Kenaf fibers can widely be used in the fabrication of composite materials due to their higher mechanical properties. Digital images of different bast fibers: (a-a1) flax fibers, (b-b1) hemp fibers, (c-c1) jute fibers, (d-d1) ramie fibers, and (e-e1) kenaf fibers. Keywords: Natural bast fibers; thermoplastic and thermosetting polymers; classification; biodegradability; eco-friendly and sustainable composites; properties and applications EN Natural bast fibers thermoplastic and thermosetting polymers classification biodegradability eco-friendly and sustainable composites properties and applications 8006 8021 16 11/21/22 20221220 NES 221220 Introduction Composites are generally known as materials having multifunctional physical and chemical properties, which are manufactured by using two or more individual materials of different characteristics (Mastura et al. [49]; Sahu and Gupta [78]). [Extracted from the article]

Hybrid composite materials containing natural fibers are replacing conventional materials for automobile, aerospace and sports goods structural applications. Fiber extracted from plants and man-made fibers reinforced with polymer matrix find many applications because of improved characteristics, such as light weight and high strength. In this work, fabricated hybrid composites using chemically treated abaca, kenaf and carbon fiber reinforced with epoxy and teta hardener are studied. Hybrid composites have four stacking sequences and five layer composites made up of hand laid up then compression molding. Produced hybrid composites are subjected to various loads to determine the mechanical strength. Moisture absorption measured in the distilled water was used as the medium during water absorption test. Experimental results showed that the treated fiber hybrid composite provided higher mechanical strength and absorbed less moisture. The morphology of fractured surfaces was analyzed by electron microscopy. [ABSTRACT FROM AUTHOR]

The application of a sandwich structure made with composite facesheet and honeycomb core has increased rapidly due to high stiffness to weight ratio characteristics. There is a growing interest in using natural/synthetic hybrid composite to enhance the mechanical performance of natural fiber and reduce the environmental impact compared to synthetic materials. This study investigates the mechanical properties (tensile, edgewise compression, flexural) of the honeycomb sandwich structure with the hybrid composite facesheet, reinforced with different kenaf and glass fiber ratios. Non-hybrid kenaf and glass fiber composites were fabricated for comparison. The result showed that increasing the glass fiber ratio in a hybrid facesheet significantly improved the mechanical performance of the sandwich structure. Compared to the non-hybrid kenaf composite, the hybrid composite showed improved tensile and compression strength by up to 233% and 79%, respectively. The hybrid composite (glass/kenaf/glass) achieved 76% tensile modulus and 87% compression strength of glass fiber composite when the results were normalized. The specific flexural stiffness of the hybrid facesheet using glass fiber in the outer layer exhibited comparable performance by obtaining 89% flexural stiffness of non-hybrid glass composite sandwich structure. [ABSTRACT FROM AUTHOR]

This study sustainably developed natural fiber composites from extracted nano-cellulose (ENC) from waste paper egg trays and incorporated them into vinyl ester/kenaf fiber (ENCVK) composites using a vacuum-assisted resin transfer molding (VARTM) process. Overhead stirring, three-roll milling, and ultrasonication were used to uniformly mix the ENC into the resin. The surface morphology exhibited a homogeneous distribution of ENC in the composites, and change in the % of transmittance of spectral peaks refers to the chemical interaction of ENC with the VK composites. ENC significantly improved tensile (32 MPa), flexural (77 MPa) and impact (0.0197 J/mm2) properties of the VK composites (18 MPa, 61 MPa and 0.009 J/mm2) by approximately 73%, 25% and 110%, respectively. Further, ENC inclusion enhanced the storage modulus of VK composites owing to the addition of rigid ENC particles, which enhances the bearing capacity of the composite and is reflected in its high performance. The loss modulus indicates that the interfacial interaction of ENCVK is more vital than VK. The tan Δ value indicates that the filler has strong adhesion, and the polymer cohesion damping is reduced, thus reflecting its high performance. [ABSTRACT FROM AUTHOR]

Alkali treatment of natural fibers will improve the mechanical, chemical, and thermal characteristics of natural fiber reinforced epoxy composites. The influence of alkali treatment on the improvement of mechanical strength of natural fiber reinforced epoxy composites depends on the selection of process parameters of the treatment. In this work, the optimization of four key process parameters for alkali treatment of kenaf fiber has been studied using orthogonal array-oriented fractional factorial experimental design. The concentration of sodium hydroxide solution, process temperature, time, and fiber to solution weight ratio were the four chosen parameters and the tensile strength of the composite sample fabricated with treated kenaf fiber and epoxy resin was taken as output response. The hand layup method was used to fabricate the composite materials, and specimens were prepared for the tensile test. All samples were fabricated by ensuring the fiber weight ratio of 40%. Five samples were prepared at each experiment category, and mean values were taken for analysis. The results revealed that 6% NaOH solution, 30°C process temperature, 8 hours process time, and 1:15 fiber to solution weight ratio are identified as optimum process parameters for a tensile strength of 58.16 MPa. [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]

The effect of different concentrations of epoxy surface coating treatment on the thermal and mechanical properties of kenaf fiber reinforced recycled poly (ethylene terephthalate) (RPET) composites was studied. Silane-treated kenaf fibers (SKF) were epoxy-coated with optimized coating concentrations (in the ratios of 1:4, 1:5, and 1:6 epoxy to acetone solutions) to improve the thermal degradation/decomposition resistance and interfacial bonding with RPET matrix. The different epoxy coated-silane treated kenaf fibers 1:4 ESKF, 1:5 ESKF, and 1:6 ESKF were compounded with RPET at an optimized temperature of 240°C, and their constituents' composites KF/RPET, 1:4 ESKF/RPET, 1:5 ESKF/RPET, and 1:6 ESKF/RPET were subjected to thermal, mechanical and microstructural investigation. The obtained results showed some remarkable effects of epoxy concentrations on the chemical and surface structures of the treated fibers. Thermal properties of both ESKF and ESKF/RPET composites were more stable and improved with different concentrations of epoxy treatment compared to the untreated counterparts. 1:4 ESKF and 1:5 ESKF were the most thermally stable with onset degradation and DTG decomposition temperatures of 331.6°C and 381.7°C, and 324.0°C and 388.7°C respectively. Mechanical properties of the epoxy-coated composites were higher and further improved with epoxy concentrations and fiber loadings compared to uncoated composites. Hence, the epoxy concentration of 1:4 gave the maximum tensile and impact properties, and at 10 wt. % fiber loading within the lower loading regions, followed by 1:5 with outstanding flexural properties. The coated-treated composites showed strong fiber/matrix bonding with no evidence of fiber decomposition compared to the untreated composites with poor fiber/matrix interaction. The current research findings are original and valid for improving the thermal degradation resistance and stability of natural fibers, and the mechanical properties of natural fiber reinforced engineering thermoplastic composites. The epoxy coated – silane-treated textile kenaf fibers reinforced with recycled PET composites have the potentials to be utilized in high-temperature industrial and engineering applications. Graphical Abstract [ABSTRACT FROM AUTHOR]

Several industry sectors have sought to develop materials that combine lightness, strength and cost-effectiveness. Natural lignocellulosic natural fibers have demonstrated to be efficient in replacing synthetic fibers, owing to several advantages such as costs 50% lower than that of synthetic fibers and promising mechanical specific properties. Polymeric matrix composites that use kenaf fibers as reinforcement have shown strength increases of over 600%. This work aims to evaluate the performance of epoxy matrix composites reinforced with kenaf fibers, by means of dynamic-mechanical analysis (DMA) and ballistic test. Through DMA, it was possible to obtain the curves of storage modulus (E′), loss modulus (E″) and damping factor, Tan δ , of the composites. The variation of E′ displayed an increase from 1540 MPa for the plain epoxy to 6550 MPa for the 30 vol.% kenaf fiber composites, which evidences the increase in viscoelastic stiffness of the composite. The increase in kenaf fiber content induced greater internal friction, resulting in superior E″. The Tan δ was considerably reduced with increasing reinforcement fraction, indicating better interfacial adhesion between the fiber and the matrix. Ballistic tests against 0.22 caliber ammunition revealed similar performance in terms of both residual and limit velocities for plain epoxy and 30 vol.% kenaf fiber composites. These results confirm the use of kenaf fiber as a promising reinforcement of polymer composites for automotive parts and encourage its possible application as a ballistic armor component. [ABSTRACT FROM AUTHOR]

Over the last few years, natural fiber-based hybrid polymers have been widely used to increase the biodegradability and cost-effectiveness of the products in many industrial applications, such as automobile construction industries. Adding filler materials provides enhanced wear properties and thermal behaviors of composites. Kenaf fiber has better strength and stiffness, and it has been used as reinforcement in polymer composites. Silicon carbide as filler material in composites modifies the mechanical properties and thermal behaviors. The present research analyzes the thermal characteristics of silicon carbide/kenaf fiber-reinforced epoxy composites with various weight percentages. Six different composite specimens were fabricated at varying weight percentages of silicon carbide. The specimens were subjected to various thermal tests, such as heat deflection temperature (HDT), coefficient of thermal expansion (CTE), thermal conductivity (TC), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The findings could serve to expand the range of application for SiC/kenaf fiber-reinforced composite, which may have better thermal stability, better performance, and lower thermal expansion than the other regularly used natural fiber-reinforced composites. [ABSTRACT FROM AUTHOR]

In this paper, the effect of integration of natural fibers in UD carbon fiber is studied. The integration of natural fibers in carbon fiber is made via intra fiber hybridization. Natural fiber hybrid composite samples were prepared for Mode I and Mode II fracture tests. XRD analysis was done for the chosen natural fibers to know the crystallinity index and then compared with Carbon and Glass fibers. The fracture test experimental results, revealed that the effect of Jute fiber integration in UD Carbon epoxy composite was found significant in getting relatively good Mode I and II fracture toughness at the crack initiation without losing its stiffness. In addition to this Kenaf Carbon epoxy composite indicated better crack suppression with 30% higher propagation toughness values as compared to other hybrid combinations and pristine composites. It is observed that integration of jute fibers in UD carbon epoxy composites was significant in achieving good mode I and mode II fracture toughness at the crack initiation without losing its stiffness and also kenaf carbon epoxy composites indicated better crack suppression with 30% higher propagation toughness as compared to other hybrid combinations used. [ABSTRACT FROM AUTHOR]

In recent years, natural fibers have been used more frequently for their lower weight to strength ratio, low cost, and environmental-friendly attributes. In this work, sisal/kenaf fiber reinforced with epoxy matrix hybrid composite (HC) was manufactured and their mechanical properties were compared with the sisal fiber composite (SFC) and kenaf fiber composite (KFC). Water absorption was carried out to find the moisture absorption capacity of the manufactured HC. HC provides better properties when compared with SFC and KFC. Hybrid composite is suitable for light weight automobile applications. [ABSTRACT FROM AUTHOR]

Hybrid laminates made using natural fibers have been finding applications in diverse fields such as automotive parts, building structures and sports goods. These laminates incorporate the benefits of the reinforcements used in constructions. The present work deals with the fabrication of hybrid laminate comprising of the natural fibers areca and kenaf in varying stacking sequences through the hand layup method. Epoxy resin (LY556) and hardener (HY951) are mixed in the ratio of 10:1 to prepare the matrix material. Six different hybrid laminates having five layers of areca and kenaf in different stacking sequences are produced. Two more laminates having either kenaf or areca in all the five layers and are produced to act as reference laminate. The prepared laminates are cut as per ASTM standards and subjected to tensile, compressive, flexural, impact and hardness tests in order to identify the properties of the fabricated laminates. The result shows that composite made with kenaf fiber as skin material and areca as core materials exhibit better tensile, flexural and hardness properties. Likewise, composites with outer layers of areca and core layers of kenaf fibers have high compressive and impact strength. The fractured surfaces after the mechanical tests are investigated through the Scanning Electron Microscope (SEM). [ABSTRACT FROM AUTHOR]

Fiber obtained naturally which is bio-degradable and extracted from plant species. Hibiscus Vitifolius Stalk Fiber (HVSF) when used in concrete increases the ductility for both new and old structures under specific treatment to avoid degradable. The application of fiber in the concrete structure is increased due to behavioural property of high tensile, high straining, high modulus, thermal resistance, low density, impact load resistance, non-toxic and good resistance to chemical attack. The flexural behaviour of the concrete is investigated and evaluated the optimum thickness of fiber in the soffit of the beam by eliminating delamination. The effectiveness of optimum thickness of fiber improved the ultimate load, ultimate deflection and improved in crack resistance. [ABSTRACT FROM AUTHOR]

In engineering, composites have indicated a more profound influence in the recent development of materials with high strength to weight ratio. The purpose of this work is to identify the different and specific properties which a composite possesses when various reinforcement fibres are used in different epoxy matrix material. Composite materials have a major role to play with meeting that requirement. Many natural fibre composite materials possess good mechanical properties but still lack in satisfying applications requirements and alternate for which is seen as sandwich natural fibre composites. In this investigation, an effort has been made to study the mechanical properties exhibited by sandwich epoxy composite reinforced with various commonly used natural fibres, namely Aloevera, Kenaf, Sisal, Jute and Flax. The polymer resin used as matrix is also varied using Epoxy LY556 and Epoxy GY250. The originality of this work is in the use of Epoxy GY250 to fabricate sandwich composites with five commonly available natural fibres and compare its performance to the more widely used Epoxy LY556. It has been determined through various mechanical tests, which particular epoxy resin bonds better with the natural fibres namely, jute, sisal, aloe vera, kenaf and flax thereby providing better tensile, impact and flexural properties. The investigation is hoped to provide an insight into how the environmentally friendly natural fibres interact with the varying matrix resins and how this interaction affects the mechanical properties of said composites. [ABSTRACT FROM AUTHOR]

Natural cellulosic fibres, such as kenaf, have potential for use as replacement of man-made fibres in polymeric composites. The rapid depletion of synthetic resources, such as petroleum, and the growing consciousness of global environmental problems related to synthetic products push toward the acceptance of natural fibres as biocomposite components. Kenaf (Hibiscus cannabinus L.) is a multipurpose hibiscus species used to make engineered wood, clothing, packing material, rope and twine. Kenaf is essentially made up of cellulose (about 70%), predicting its excellent mechanical performance. Kenaf fibres are chemically treated before mixing with other polymer resins to enhance their fibre properties. Based on the previous literature, the effect of chemical treatment on the dynamic mechanical performance of kenaf cellulosic biocomposites remains unexplored. The present review focuses on the recent works on the influence of major chemical treatments used on kenaf fibre, such as alkaline, silane and acetylation on fabricated biocomposites. The present review also unveils other chemical treatments (e.g. zein and amino acid) and combined treatments on the fibre to improve the biocomposites' dynamic mechanical behaviour. [ABSTRACT FROM AUTHOR]

To minimize the surface roughness and delamination problems during the end milling of natural fiber reinforced composites (NFRCs), it is essential to understand the effects of the machining parameters (spindle speed and feed rate) and the kinematics of material removal. In this study, the effects of machining parameters on the machined surface quality – surface roughness (Ra) and delamination factor (Fd), during end milling of kenaf, jute and rice husk (RH) reinforced polypropylene (PP) composites has been analyzed using a two-factor, three-level experimental plan. It has been noticed that there are significant differences in the silicon contents (kenaf: 0.57%, jute: 4.16% and RH: 22.2%) and hardness values (kenaf: 0.15, jute: 0.20 and RH:0.59 GPa) of the three natural fibers, which has influenced the resulted surface quality of the machined NFRCs. Kenaf/PP composites showed the lowest delamination damages and the best surface finish most likely due to the fiber composition and morphology of kenaf, while predictably, RH/PP composites were the most demanding to machine. With a statistical analysis on the results, it is concluded that the machined surface quality is more influenced by spindle speed with percentage contribution showing at least three times more than feed rate for machining NFRCs. [ABSTRACT FROM AUTHOR]

The increasing demand for high performance and lightweight materials has stimulated the development of alternative materials, namely fiber metal laminates (FMLs). FML is a sandwich structure which is formed by bonding the metallic layers with composite as core constituent using an adhesive agent. In this study, the mechanical behavior of FMLs with the core constituents of environmental friendly kenaf bast fiber reinforced polypropylene composites bonded with aluminum skin layers was investigated. The effects of fiber compositions (50, 60, and 70 wt.%), fiber lengths (30, 60, 90 mm), and alkali treatment on the mechanical responses of FML were investigated. The overall results revealed that the increase of fiber composition and fiber length reduces the mechanical strength of FML owing to the agglomeration of natural fibers when the fiber length exceeds the critical limit. However, the chemical treated kenaf bast fiber reinforced FML showed a significant enhancement of the mechanical properties in comparison to the non-treated fiber reinforced FML owing to the improved fiber-matrix adhesion level. [ABSTRACT FROM AUTHOR]

The identification of the percolation threshold (Φ c) in short fiber composites is a challenging problem in Composite Science. Above Φ c the fibers form a continuous network that causes substantial changes in mechanical and transport properties. Besides, percolation of natural fibers in biodegradable polymer matrices allows water and other pro-degradative species to access the inner parts of the material from the external environment, accelerating biodegradation. Whether such a speeding up is desired or not, assessing Φ c in composites is of utmost importance. Unfortunately, natural fibers are not conductive and exhibit highly variable shape and physical properties. This prevents the use of many experimental and theoretical approaches for the estimate of Φ c. Here we propose an original rheological approach borrowed from the viscoelastic modelling of polymer nanocomposites. The method was applied to two systems made of poly(lactic acid) filled with hemp or kenaf fibers (average length <500 μm, average length-to-diameter ratio <5). The estimate of Φ c (∼10.1 and 19.5 vol% for the hemp- and kenaf-based composite, respectively) required a single set of simple linear viscoelastic measurements, and the computed values were in good agreement with those obtained through time-consuming (measurement times >3 weeks) dielectric spectroscopy analyses (∼10.1 and 18.5 vol%). [Display omitted] [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]

This paper presented the mechanical and fatigue behavior of woven kenaf fiber reinforced epoxy composites with the composition of 16.67% kenaf and 83.33% of epoxy (1:5 weight ratio) alongside the addition of 1% of silica aerogel into the composite. There are a number of studies concentrating on natural fibers nowadays, yet their low mechanical properties when compared to other synthetic fibers had urged the addition of filler into the composite to increase the mechanical strength. Hand layup technique was used to prepare Kenaf/Epoxy (KE) and Kenaf/Epoxy/Silica Aerogel (KES) composite alongside pure epoxy (E), 100% epoxy composite. All fatigue tests were conducted at constant stress amplitude, frequency of 5 Hz, stress ratio of 0.5 and the maximum stress applied was from 90 % to 70 % of ultimate tensile strength with decrement of 5%. The results showed that the tensile properties improved as silica aerogel is added into the composite. These results showed that the tensile strength is increased by 27.3% while stiffness decreased by 78.2% when silica aerogel is added into the composite as filler. The reduction of the stiffness is associated with the brittle nature of the filler. Similar to tensile properties, the addition of silica aerogel also had resulted better fatigue life. KES composite showed more than 100% increment in number of cycles endured when compared to KE composite. [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]

Investigation on the fatigue life of hybrid composites is critical to extend their applications and acceptance among industries; however, there is a lack of research focus on fatigue performance of the hybrid composite. In this study, the fatigue life of glass/kenaf woven-ply hybrid composite with thermoplastic and thermoset polymer matrix was investigated. Hybrid composites consist of two different fibre configurations: kenaf/glass/kenaf and glass/kenaf/glass. Thermoplastic hybrid composites were manufactured through the hot press moulding compression method, while thermoset hybrid composites were fabricated through the vacuum-assisted resin infusion method. The tensile strength and fatigue strengths of the kenaf/glass/kenaf composite have been identified to be significantly lower than those of the glass/kenaf/glass composite regardless of the types of matrix used. However, thermoplastic-based kenaf/glass/kenaf composites are less fatigue sensitive compared to glass/kenaf/glass composites; however, this phenomenon is vice versa for thermoset composites due to the epoxy matrix, which limits the stiffening effect in natural fibres. [ABSTRACT FROM AUTHOR]