Kenaf Fiber Reinforced Polymer Composites Research Articles

Tensile properties and dynamic mechanical analysis of kenaf/epoxy composites

Kenaf fibre-reinforced polymer composites could offer low-cost, biodegradable, recyclable, and renewable materials. The hydrophilic kenaf fibres exhibit poor compatibility with the hydrophobic epoxy matrix as compared to their synthetic counterparts and ultimately, this may severely constrain their potential as a green composite material. This work aims to evaluate the tensile properties and dynamic mechanical analysis (DMA) of kenaf fibre composites reinforced with two epoxy systems as matrices, B and M resins. Neat epoxy samples and kenaf-reinforced composites with varying fibre loading, 15% and 45% were fabricated in the study. It was found that the tensile properties of kenaf composites are dependent on the epoxy resin systems and higher with reinforcement content. The tensile strength of M-15% and M-45% are 16.3% and 12.0% stronger than their counterparts. Determination of interfacial shear strength using a modified micromechanical model was employed showing that M-45 has a higher value than B-45%, 107.09 kPa and 90.28 kPa respectively. By DMA, in general, an increase in the storage modulus and peak height in the loss modulus was always higher with kenaf composites that were manufactured with the M resin system. The adhesion factor, A calculated from tan delta curves and cole-cole plot has shown the state of fibre/matrix adhesion level in each epoxy resin system. The SEM analysis indicates the presence of void spaces around fibres and matrix may attributed to the lower compatibility of the B resins system used in kenaf composites fabrication.

Effect of silane treatments on mechanical performance of kenaf fibre reinforced polymer composites: a review

Natural cellulosic fibres, such as kenaf, can be used in polymeric composites in place of synthetic fibres. The rapid depletion of synthetic resources such as petroleum and growing awareness of global environmental problems associated with synthetic products contribute to the acceptance of natural fibres as reinforcing material in polymer composite structures. In Africa and Asia, kenaf is considered a major crop used for various cordage products such as rope, twine, and burlap and in construction, it is used for thermal insulation of walls, floors, and roofs and soundproofing solutions. In the furniture and automotive industry, it is used to manufacture medium-density fibreboard and other composite materials for structural applications. Kenaf is primarily composed of cellulose (approximately 40%–80%), which accounts for its superior mechanical performance. Kenaf fibres are chemically treated before mixing with the polymer matrix to improve their fibre interaction and composite performance. The alkaline treatment with sodium hydroxide (NaOH) solution is the most frequently used chemical treatment, followed by a silane treatment. Numerous chemical concentrations of NaOH and silane solutions are investigated and several combined treatments such as alkaline-silane. The present review discusses the effect of silane treatments on the surface of kenaf fibre on the fabrication of polymer composites and their mechanical properties.

Experimental investigation of impact strength of kenaf fiber reinforced polyester composite

The use of natural fibers as reinforcement in polymer composites has become a very popular research area of scientists, researchers and engineers throughout the last decade. Natural fibers have significant properties like low density, high specific strength, low cost, relatively good mechanical properties, eco-friendly and bio-degradability. Due to this, they are used as substitute for the conventional fibers such as glass, aramid and carbon. Recently, it was noticed that kenaf fiber had enormous possibilities for replacing synthetic fiber in composites due to the rising environmental and ecological issues. This consciousness has inspired the efforts for the development of new innovative bio-based composites. In this research work, an experimental investigation has been carried out to make use of kenaf fiber, a natural fiber abundantly available in India. The present work describes the development and characterization of a new set of kenaf fiber reinforced polymer composites. The composites are fabricated using hand lay-up technique and their impact strength is evaluated. The experiments are carried out to study the effect of fiber length and fiber orientation on the impact strength of these composites. The fabricated composites were tested as per ASTM standards to evaluate its impact strength. The experimental results show the notable effect on impact strength of prepared composites. However it is found that the reinforcement of kenaf fiber with preferred orientation can improve the impact strength significantly.

Tensile and Flexural Properties of Silica Nanoparticles Modified Unidirectional Kenaf and Hybrid Glass/Kenaf Epoxy Composites.

This paper investigates the influence of silica nanoparticles on the mechanical properties of a unidirectional (UD) kenaf fiber reinforced polymer (KFRP) and hybrid woven glass/UD kenaf fiber reinforced polymer (GKFRP) composites. In this study, three different nanosilica loadings, i.e., 5, 13 and 25 wt %, and untreated kenaf fiber yarns were used. The untreated long kenaf fiber yarn was wound onto metal frames to produce UD kenaf dry mat layers. The silane-surface-treated nanosilica was initially dispersed into epoxy resin using a high-vacuum mechanical stirrer before being incorporated into the UD untreated kenaf and hybrid woven glass/UD kenaf fiber layers. Eight different composite systems were made, namely KFRP, 5 wt % nanosilica in UD kenaf fiber reinforced polymer composites (5NS-KFRP), 13% nanosilica in UD kenaf fiber reinforced polymer composites (13NS-KFRP), 25 wt % nanosilica in UD kenaf fiber reinforced polymer composites (25NS-KFRP), GKFRP, 5 wt % nanosilica in hybrid woven glass/UD kenaf fiber reinforced polymer composites (5NS-GKFRP), 13 wt % nanosilica in hybrid woven glass/UD kenaf fiber reinforced polymer composites (13NS-GKFRP) and 25 wt % nanosilica in hybrid woven glass/UD kenaf fiber reinforced polymer composites (25NS-GKFRP). All composite systems were tested in tension and bending in accordance with ASTM standards D3039 and D7264, respectively. Based on the results, it was found that the incorporation of homogeneously dispersed nanosilica significantly improved the tensile and flexural properties of KFRP and hybrid GKFRP composites even at the highest loading of 25 wt % nanosilica. Based on the scanning electron microscopy (SEM) examination of the fractured surfaces, it is suggested that the silane-treated nanosilica exhibits good interactions with epoxy and the kenaf and glass fibers. Therefore, the presence of nanosilica in an epoxy polymer contributes to a stiffer matrix that, effectively, enhances the capability of transferring a load to the fibers. Thus, this supports greater loads and improves the mechanical properties of the kenaf and hybrid composites.

Effect of MWCNT Surface Functionalisation and Distribution on Compressive Properties of Kenaf and Hybrid Kenaf/Glass Fibres Reinforced Polymer Composites.

The aim of this study is to evaluate the effect of surface treated multi wall carbon nanotubes (MWCNTs) on compressive properties of the unidirectional (UD) kenaf and hybrid woven glass/UD kenaf fibre reinforced polymer composites. The MWCNTs were first treated using concentrated acid (a mix of H2SO4 and HNO3) and silane (three-aminoprophyltriethoxysilane) in order to improve the dispersion within the epoxy matrix using a high shear roll milling technique. In this study, nanomodified epoxies were prepared using 0.5, 0.75 and 1.0 wt % of pristine MWCNT (PCNT), acid treated MWCNT (ACNT) and silane treated MWCNT (SCNT). These nanomodified epoxies were then used for the fabrication of kenaf and hybrid composites using combination of filament winding and resin impregnation. The uniaxial compression test was conducted using a universal testing machine according to the ASTM D3410 standard. The morphology of fractured samples was observed and analysed using scanning electron microscopy (SEM) in order to evaluate the failure behaviour and mechanisms involved during compression. It was found that the addition of treated MWCNT (ACNT and SCNT) improved the compressive properties of kenaf and hybrid composites as compared to those of untreated-MWCNT (PCNT). The addition of 1.0 wt % of SCNT exhibited good compressive properties in both kenaf and hybrid composite systems. The compressive modulus and strength increased by 73.25% and 20.15%, respectively, for composites made of 1.0 wt % SCNT and Kenaf (1.0SCNT/K). For the hybrid composites, the compressive modulus and strength increased by 21.18% and 7.73% for composites made of 1.0 wt % SCNT filled G/K composites (1.0SCNT/G/K).

Flexural Properties of Chopped Kenaf and Carbon Fibre Reinforced Polymer Composites Embedded with Carbon Nanotubes

An experimental study was performed to investigate the flexural behaviour of chopped kenaf and carbon fibre reinforced polymer composites embedded with carbon nanotubes (CNT). The fibre content in the composites was 10 wt.% with three different CNT loadings, which were 0.5wt.%, 1.0wt.%, and 1.5wt.%. The CNT were dispersed in the epoxy resin using the mechanical stirrer and three-roll mill machine and mixed with the chopped fibres before being poured into the designated mould. Three-point bending tests were conducted with a specimen thickness and width of 4 mm and 10 mm, respectively, and a standard specimen length of 20% longer than the support span. The flexural test results showed that the chopped carbon fibre reinforced polymer (CFRP) with 0.5wt.% CNT exhibited the highest flexural strength and modulus (42 MPa and 2.9 GPa, respectively) compared to other composites with 1.0wt.% and 1.5wt.% CNT loading. The chopped kenaf fibre reinforced polymer (KFRP) composite with 0.5wt.% CNT loading showed the highest increase in the flexural strength and modulus, at 30 MPa and 2.8 GPa, respectively. Hence, it was concluded that the addition of CNT improved the flexural properties and 0.5 wt.% CNT was the ideal loading to enhance the flexural properties of chopped fibre-reinforced polymer composites.

A Review on Applications of Kenaf Fibre Reinforced Composites

Natural fibres namely sisal, jute, kenaf, hemp, abaca and banana are mainly used in industries for developing Natural fibres composites. They find many applications such as automobiles, furniture, packing and construction due to many merits such as their low cost, good mechanical properties, non-toxic, low weight, less damage to processing equipment, improved surface finish, abundant and renewable resources. The objective of this paper is to review the applications of various kenaf fibre reinforced polymer composites which will provide a base for further research in this area.

Mechanical properties of functionalised CNT filled kenaf reinforced epoxy composites

This paper aims to study the effect of functionalised carbon nanotubes (CNT) on mechanical properties of kenaf fibre reinforced polymer composites. The CNT was functionalised using acid mixtures of H2SO4:HNO3 and 3-Aminopropyl Triethoxysilane before it was incorporated into epoxy resin. Three different types of CNT were used, i.e. pristine (PCNT), acid-treated (ACNT) and acid-silane treated (SCNT), to fabricate kenaf composite. Three different filler contents were mixed in each composite system, i.e. 0.5, 0.75 and 1.0 wt%. The functionalised CNT was characterized using x-ray Diffraction (XRD), Fourier Transform Infrared (FTIR) and Transmission Electron Microscopy (TEM). Tensile, flexural and Izod impact tests were conducted in order to evaluate the effect of CNT contents and surface treatment of mechanical properties of kenaf composites. It was observed that the inclusion of 1 wt% acid-silane treated CNT improved the tensile, flexural and impact strengths of kenaf/epoxy composite by 43.30%, 21.10%, and 130%, respectively. Silane modification had been proven to be beneficial in enhancing the dispersibility and reducing agglomeration of CNT in the epoxy matrix.

Tensile Behaviour of Kenaf Fiber Reinforced Polymer Composites

Natural fiber is usually used as reinforcement in polymeric materials, and short fibers are commonly used for non-structural applications. However, the lack of studies on long fiber reinforced polymeric materials, especially kenaf fiber, has limited its usage in Malaysia. This paper presents the experimental results of a series of tensile tests conducted on continuous kenaf fibers produced with different types of thermoset resin (epoxy, polyester, and vinyl ester) arranged longitudinally. A total of 75 kenaf fiber reinforced polymer composites containing up to 50% fiber volume fraction including 15 neat samples as control samples were produced. Then, the samples were tested using Universal Testing Machine to obtain their tensile behaviour. Results indicated that the composites’ performance increased gradually with every increment of fiber volume fraction. Factors affecting the tensile behaviour of kenaf fiber reinforced polymers are also explained and discussed. In conclusion, kenaf fiber can be used as reinforcing materials in polymeric materials.

Kenaf Fiber Reinforced Polymer Composites for Strengthening RC Beams

This paper presents the findings of an experimental study to investigate the structural behavior of reinforced concrete (RC) beams externally strengthened with various types of kenaf fiber reinforced polymer composite laminates with 50% fiber volume content. The experimental parameters including flexural strength, stress-strain relationship, deflection, tensile stress and young modulus of beams strengthened by different kenaf fiber reinforced polymer composites are dis- cussed. In order to test the flexural strength of the RC beams, a total of eight beams divided into two series were used. In each series, every two of the beams were strengthened with kenaf/epoxy, kenaf/polyester, and kenaf/vinyl ester com- posite laminates respectively. The remaining two were kept as control specimens. The experimental moment capacity of each beam was calculated using tensile strength and young modulus of the composites. Comparisons were made on the load-deflection, strain behavior and failure mode. Moreover, theoretical moment capacity of each beam was calculated using conventional formulation to verify experimental results. The research findings indicated that all strengthened beams improved structural performance where the maximum flexural strength increase by 40% and maximum deflec- tion reduced by 24%.

Review of kenaf fiber reinforced polymer composites

General characteristics of kenaf fibers and mechanical properties of its polymer composites (dependently on the environmental conditions) as well as applications directions of such materials have been presented.