Coir Composites Research Articles

The amount of coir composition effect on the flexural and tensile strength of coir composites

This article is the result of research on the effect of soaking coir in sodium hydroxide solution. The objective of this study is to determine the effect of the composition of coir on the flexural and tensile strength of the coir composite as an effect of immersion in a sodium hydroxide (NaOH) solution. The stages of conducting the research are: (1) preparation of materials and tools; (2) treatment of coir and manufacture of composites; (3) tensile and flexural testing. Before being used as a composite reinforcement, coir was soaked in sodium hydroxide solution with a concentration (percent by weight) of 5% and 10% for 3 hours at room temperature 25oC. After that, the coir was washed with distilled water and then dried at room temperature for 18 hours. Next, we dried the coir in an oven at 90oC for 5 hours. After soaking, coir was used as a composite reinforcement with a composition of 10%, 15%, and 20% by weight of coir. The composite was made using the hand lay-up method, while the flexural test specimens were made based on ASTM-D790, and the tensile test was based on ASTM D 638-03. Then the flexural strength test of the coir composite was carried out using the Shimadzu Flexure Tester with a capacity of 5 kN and a compressive speed of 2 mm/minute. It was concluded that the highest flexural and tensile strengths were obtained by immersing coir in a 5% NaOH solution with 20% coir composition, respectively 41.114 MPa and 20.265 MPa.

Assessing the electromagnetic shielding effectiveness of coconut coir composites with varying iron particle concentrations

This study investigates the electromagnetic shielding effectiveness of Coconut Coir-based Porous Carbon (CCPC) composites with varying iron (Fe) particle concentrations, specifically focusing on four different weight ratios of CCPC/Fe-80, CCPC/Fe-60, CCPC/Fe-40, and CCPC/Fe-20. The novelty of this work lies in the use of sustainable coconut coir as a base material, emphasizing its eco-friendly and cost-effective attributes for Electromagnetic interference (EMI) shielding applications. The significance of varying iron particle concentrations is highlighted to optimize electromagnetic shielding effectiveness. Comprehensive analyses were conducted on these composites. X-Ray Diffraction (XRD) analysis confirmed the presence of crystalline Fe particles and amorphous carbon, with crystalline sizes determined via Williamson-Hall (W-H) plot, Scherrer Equation, and Strain Size Plot (SSP) ranging from 17.33 nm to 18.01 nm for the former. Raman spectroscopy revealed distinctive D and G bands, with intensity ratios indicating a slight increase in structural disorder with higher Fe content. UV-Visualization spectroscopy demonstrated distinct absorption peaks, with higher Fe content resulting in more pronounced absorbance and lower band gap energies. Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) analyses provided detailed insights into the material's microstructure and elemental composition, confirming the successful integration of Fe particles within the porous carbon matrix. Vector Network Analyzer (VNA) testing measured the reflection loss (RL), showing values in the range of −26.4 dB to −20.2 dB, for 2 mm thick samples, corresponding to electromagnetic wave attenuation of over 99%. These results underscore the potential of CCPC/Fe composites, particularly in applications requiring effective Electromagnetic (EM) wave attenuation. This research offers a sustainable and cost-effective solution, contributing significantly to the field of materials science by enhancing electromagnetic compatibility in various technological applications.

Mechanical, wear and thermal properties of natural fiber-reinforced epoxy composite: cotton, sisal, coir and wool fibers

Natural fiber-reinforced epoxy composites (NFRCs) have gained significant attention in recent years due to their potential as environmentally friendly and sustainable materials. These composites combine natural fibers, derived from plants, with epoxy resins to create a material with enhanced properties. The objective of this study is to investigate the mechanical, wear and thermal properties of NFRCs incorporating cotton, sisal, coir and wool fibers. The vacuum-assisted resin transfer molding (VARTM) technique was employed to produce composite plates, followed by conducting tests on tensile, wear and thermal properties. The cotton composite showcased the highest tensile strength, reaching 52.81 MPa, while the coir composite exhibited the lowest, measuring 15.34 MPa. Sisal composite exhibited a moderate wear rate (1.423 mm3/Nm) and a lower coefficient of friction (0.233), implying smoother relative motion. Coir composite presented the highest wear rate (4.615 mm3/Nm), attributed to its coarse fiber nature. Thermal conductivity is highest at cotton composite (1.017 W/mK) and is lowest at coir composite (0.187 W/mK). Additionally, the highest specific heat was observed in the coir composite (26.313 MJ/m3K). Cotton demonstrated potential for efficient heat transfer, while wool outperformed in insulation. Sisal displayed versatility for structural applications. Coir emerged as an effective insulator with energy-saving applications.

Water aging effects on the flexural properties of fully biobased coir fiber composites

AbstractThis work describes the flexural behavior of biocomposites composed of a polyurethane matrix derived from castor oil plants and coir fibers. A statistical design is performed to identify the effects of fiber alkaline treatment and aging on the flexural modulus and strength of the composites. Physical tests and failure analyses are carried out to better assess their mechanical performance. A second experiment at 100% relative humidity is performed on treated fiber composites to compare with those obtained by immersion in water. The flexural modulus of the composites is not significantly affected by the fiber alkali treatment, while the strength is reduced by 35.17% when treated fibers are considered. Increasing the exposure time of composites under both aging conditions progressively reduces their flexural properties. The aging process of biocomposites in an environment with 100% relative humidity takes twice as long to reduce to the same flexural properties as those aged in water.Highlights Composites made with treated fibers showed higher apparent density and lower porosity. Water aging reduces flexural modulus and strength of biobased coir composites. The bending properties are strongly dominated by the properties of biobased polymer. 100% relative humidity takes twice as long to reduce to the flexural properties as those aged in water. Untreated coir fibers achieve superior bending properties under moisture aging.

Investigating the lap shear adhesion of coir and glass-fibre reinforced epoxy bonding to mild steel with varying volume fractions

Bonding synthetic fibres to metals to improve strength, durability, and corrosion resistance is a prevalent practise in the automotive, marine, and aerospace industries. Lap shear adhesion, a measurement of the bonding strength between composites and metallic substrates, is essential for structural integrity. The emergence of natural fibre composites as sustainable alternatives to synthetic composites makes it essential to investigate their lap shear behaviour and the effect of fibre volume fraction on composite properties. This research investigates the adhesion behaviour of coir and glass fibre epoxy composites to mild steel. Coir fibres, which are known for their resilience and tenacity, were treated with an alkaline solution to improve their adhesion to the resin. Samples of lap shear adhesion were prepared in accordance with ASTM specifications, and tests were conducted using a tensile machine. Increasing the volume fraction of coir or glass fibres decreased the bond strength, as demonstrated by the results. Due to the fibres’ greater tensile strength and rigidity, glass fibre composites exhibited superior strength. However, under tensile loading conditions, coir fibres exhibited superior adhesion to mild steel surfaces. SEM micrographs confirmed that coir composites exhibit shear failure while glass composites exhibit fibre pull-out behaviour. This study concludes by highlighting the engineering potential of coir fibres, considering their natural properties and cost-effectiveness. It is necessary to further optimise the fiber-matrix interface and comprehend the mechanical behaviour of coir composites in order to maximise their effectiveness. To assure the long-term durability of composite-metal joints, surface preparation, adhesive type, application procedure, and environmental conditions must also be considered. At a content percentage of 10%, glass fibres exhibited 100% higher shear strength compared to coir fibres in epoxy composites. Conversely, coir fibres at 10% content demonstrated approximately 75% greater shear strength than the values obtained with 40% glass fibres. The failure mechanisms observed are delamination or fibre fracture in the bonding area under tensile and shear loading. Increasing the fibre volume fraction reduces bond strength. Factors such as limited space for the matrix, tension concentrations, and the mechanical properties of the fibres contribute to weakened bonds. Glass fibres have better strength and rigidity than coir fibres, affecting load transfer and adhesion. Interfacial bonding is crucial, and maintaining it becomes more difficult with higher fibre volume fractions, resulting in weakened bonds.

Evaluation of properties of hybrid laminated composites with different fiber layers based on Coir/Al2O3 reinforced composites for structural application

Hybrid composites produced using natural and synthetic fibers are sustainable alternative materials for different structural applications. Therefore, this study aimed to incorporate coir fiber, E-glass, synthetic fabric, and rubber sheet into epoxy matrix by adding alumina filler to the coir composite. The hand layup method was used to manufacture a hybrid laminates composite of coir/E-glass/synthetic fabric/rubber sheet with different stacking sequences. The tensile, flexural, impact, hardness properties, water absorption, and thickness swelling of the products were evaluated. Scanning electron microscopy was used to study the morphology of the fractured surfaces. The results showed that the hybridization fiber and filler can enhance the tensile properties of the products up to 280% as well as improve the water absorption performance and thickness swelling to 78%. The flexural properties decreased after the incorporation of the fiber layer to the coir/alumina composite. An increase was also observed in the flexural and impact properties after the synthetic fabric was replaced with a rubber sheet. This study revealed that the incorporation of fibers layers into a coir composite led to higher hardness resistance. Furthermore, SEM image and macroscopic fractography showed fiber breakage on the matrix, a brittle fracture of composites, and delamination failure between the rubber sheet and matrix during the bending test. Based on the results, coir/E-glass/synthetic fabric/rubber sheet hybrid composites with different layering sequences were appropriate for various structures applications.

Eco-friendly fabrication of coco coir composites for hydroponic cultivation: a green chemistry approach

A pectin-based one-pot aqueous approach was reported to valorize coco coir into multifunctional biocomposites. These biocomposites were demonstrated to be effective hydroponic growth media.

Valorization of coco coir into biocomposite materials through water-based chemistry

In this paper, an eco-friendly approach was reported to fabricate coco coir composites through water-based chemistry. The novelty of this approach lies in the water-based chemical methodology as well as the applicability of the fabricated coco coir biocomposites as proper growth media for hydroponics. In the fabrication process, the coco coir was first made reactive via azo coupling the aromatic structures of its lignin with bifunctional linkers. The reactive coco coir was then cross-linked with polyvinyl alcohol (PVA) to produce coco coir composites. Since the fabrication process was performed with water as the solvent at moderate reaction temperatures and the only byproducts were harmless inorganic salts, it is more sustainable than other existing chemical processes that employ organic solvents and produce volatile organic harmful compounds (VOCs). Additionally, a two-factor study was conducted to determine the main and interaction effects of different mass ratios of bifunctional linkers and PVA to coco coir on the bulk density and mechanical compressive strength of the coco coir composites. To highlight the applicability of our work, the carbon-to-nitrogen ratio (C/N), water holding capacity, electrical conductivity, and substrate acidity of the composites were measured to verify their suitability for hydroponic applications. The coco coir composites were shown to be durable for use as growth media to support the growth of kale (Brassica oleracea) and cherry tomato (Solanum lycopersicum) plants in a recirculating hydroponic system.

Experimental investigation on the coconut fiber reinforced hybrid gear composites

Increasingly important in the realm of engineering, composite materials are becoming increasingly popular. This work focused on natural fiber reinforced polymer composite gear components. The sheath extracted from the coconut tree (natural fiber) is used as reinforcement for the epoxy matrix in this study. These coconut coir sheaths have a number of additional advantages, including low cost, lightweight, and availability. Experimental Study the influence of coir fiber treatment on the mechanical characteristics of a coir fiber reinforced epoxy composite. When compared to untreated coir composites, the mechanical characteristics of treated coir hybrid composites improved. Moreover, 20%, 30%, and 40% volume of glass short fiber were added with coir fiber to increase the composites' stiffness. The bending strength and impact strength of hybrid composites were determined experimentally. Also, the bending strength of the coir gear tooth was analyzed by FEA analysis.

The effects of diammonium phosphate concentration on mechanical properties of coir reinforced polymer composites

Abstract The flexural strength and the impact strength of coir fibers reinforced polymer composites were studied using the universal testing machine and the impact meter. The composites sheets were prepared by melt compounding followed by the compression moulding technique. Two different concentrations i.e. 10 and 20% of diammonium phosphate (DAP) were taken for the coir fibers treatment. Both the untreated and the DAP treated coir fibers were reinforced at 10, 20 and 30 wt% for composites fabrication. The impact strength increased towards the DAP treatment to 20%. It was clearly observed from the experiment that the composites showed highest impact strength of 4.72 J/cm at the reinforcement of 30 wt% of 20% DAP treated coir fibers. The flexural strength of DAP treated coir composites were decreased for 10 and 20 wt% reinforcements than the untreated coir composites whereas at 30 wt% reinforcement the flexural strength increased. The flexural modulus value increased with the increase in DAP treatment as well as the fiber reinforcement.

Statistical analysis and investigation of tensile test data of coir composites reinforced with graphene, epoxy and carbon fibre

A successful attempt has been made to develop coir fibre composites reinforced with graphene, epoxy and carbon fibre. The carbon fibres were arranged in an intercalated manner, which is similar to the coir fibres. The percentage composition of graphene was varied as 1, 2, 4 and 6% by weight of the holding matrix. Suitable surface modifications were done by treating natural fibres by 5% NaOH and 0.3% KMnO4 for better adhesion of fibre and epoxy resin. Sonication and cetyl trimethyl ammonium bromide treatments were also done to achieve the fine scattering of graphene in the epoxy matrix in order to achieve better mechanical behaviour. Moulds were made as per D638 American Society for Testing and Materials (ASTM) standards. The treated fibres were then arranged in the mould by the conventional hand layup technique. Tensile testing was carried out to determine the mechanical properties of the composites. Two-way analysis of variance was used as a statistical tool to find the effect of parameters such as ‘Percentage composition of graphene’ and ‘Type of mould’ on the modulus of the composites. Fourier transform infrared spectroscopy was conducted to determine the interferential adhesion and homogeneous distribution of fibres in the composite matrix. At last, field emission scanning electron microscopy analyses were also done to the specimens before and after tensile testing to determine the morphology of different entities present in the composites.

Improving the Compatibility and Mechanical Properties of Natural Fibers/Green Polyethylene Biocomposites Produced by Rotational Molding

In this work, sustainable rotomolded composites based on green polyethylene (Green-PE) and natural fibers (coir and agave) were studied. Fibers’ surface was treated with maleated polyethylene to improve the fiber-matrix compatibility. Samples were characterized by morphology, mechanical properties (impact, tension, and flexion) and water absorption. Results showed a more homogeneous morphology with better fiber dispersion and wetting in the treated fibers composites which lead to substantial improvements of tensile modulus from 258 MPa for the neat matrix up to 345 MPa for both, treated agave and coir composites (at 30% wt), and tensile strength from 13.7 MPa for Green-PE to 15.3 MPa for 30% treated coir composites. The positive effect of the surface treatment was also observed in flexural strength with increases up to 100% and 34% in flexural modulus. Also, impact strength was increased up to 46% and water absorption reduced up to 55% for treated fiber composites compared to untreated fiber composites. As an important observation, it was possible to obtain similar or even higher mechanical properties with the Green-PE natural fiber composites than for a petroleum-based rotomolded polyethylene, which is interesting in terms of sustainability and performances for specific applications like automotive and packaging.

Sustainable composites: Processing of coir fibres and application in hybrid-fibre composites

Coir fibres, a byproduct of the coconut industry, have high performance qualities but are difficult to process by conventional textile methods. The purpose of the research is to combine the processibility of hemp and flax with the high-performance properties of coir to create a composite product worthy of industrial applications. The evaluation of coir fibre-reinforced composites focuses on the processibility of the coir fibre into a nonwoven, how well it interfaces with polylactic acid and an analysis of how the mechanical properties of the final product change when mixing coir with hemp and flax. The results show that the hybrid samples outperformed most of the researched values for coir composites, despite the reduced properties of control samples as in comparable research. Adding just 10% of either flax or hemp dramatically increased the mechanical properties compared to the pure coir–polylactic acid composite.

Mechanical Properties of Epoxy Resin Matrix Composites Reinforced with Jute Fiber, Coconut Coir and Human Hair

Presently scientist and engineers are looking for the new generation of materials that are easily biodegradable as well as maintain sustainability to protect our environment. Concept of smart materials and recycling of the waste materials are the key considerations at the face of material scientist. Nowadays natural fiber composites are preferred over conventional synthetic fiber composites in many industrial applications. In this study jute fiber, human hair and coconut coir reinforced composites bonded with epoxy resin were prepared using hand lay-up technique to compare their mechanical properties. For this purpose, an open type wooden mould was used. This study reveal that the jute fiber reinforced composite exhibit better toughness, tensile and shear strength than human hair and coconut coir composites. Also it shows that human hair composite has better hardness property than jute fiber and coconut coir composites. Overall jute fiber and human hair composites show far better mechanical properties than coconut coir composite.

PP-coir Composites (PPCC): Fabrication and Study of Flexural Properties

Today we are more concern about the environment. Synthetic polymers are the most responsible pollutant for environmental pollution. Good replacing agents for the synthetic polymers are the natural polymer. That is why the uses of natural fiber reinforced composites are increasing day-by-day. In this research natural polymer coir fiber was used as the reinforcing agent with the synthetic polymer polypropylene. PP-coir composites were fabricated using a simple hot press molding method. The prepared composites were characterized by the density, tensile, and flexural properties. The effect of fiber addition on some physical and mechanical properties was evaluated. The density increases with the increase of fiber addition. The tensile strength of fabricated product increases with the increase of fiber addition up to 10% (wt.) and then decreases continuously. The elongation of fabricated product decreases with the increase of fiber addition continuously. The changes in the mechanical properties were broadly related to the accompanying interfacial bonding of PP- coir composites (PPCC). It revealed that the introduction of short coir fiber led to a slightly improved thermo oxidative stability of PP- Coir composites. The flexural strain of fabricated product decreases continuously with the increase of fiber addition. But here untreated fiber reinforced composites show higher strain than that of treated fiber reinforced composites.

Synthesis and mechanical behavior studies of bio-waste derived low-cost composite materials

Abstract Composite materials are the tailor- made multifunctional materials consisting of suitable physical and mechanical properties for the applications in various fields such as aerospace, sensitive electronic equipment, marine, civil construction, etc. In this work, a bio-waste derived composite material was synthesized using compression molding of cashew nut shell liquid (CNSL) (bio-waste resin) along with 3% paraformaldehyde, coconut coir, and sugarcane bagasse. Fibers separated from coconut husk and sugarcane bagasse were collected locally (at Tenali) and used for the synthesis after post-treatment. Those samples were separately treated with 0.1 N NaOH solution for the activation and dried at room temperature before preparation of composite material. Coconut coir, sugarcane fibers, and Cashew nut shell based hybrid composite specimens were tested for tensile strength using Electronic Tensometer. Sugarcane fibers, Coconut coir, and Cashew nut shell resin based hybrid composite exhibited a tensile strength of 11.5 Mpa, 2.6 MPa, and 5.9 MPa, respectively and tensile modulus of the sugarcane fibers, coconut coir and hybrid composite are 4.8 GPa, 0.4 GPa, and 0.5 GPa, respectively. The surface morphology was studied using scanning electron microscopy. The topography of the composite material showed a smooth surface devoid of any morphological features. Further, the composite material will be tested for the suitability of the application.

HDPE- Coir composites–fabrication, process parameters and properties

The composites of biodegradable high density polypropylene (HDPE) reinforced with short coir fiber were prepared by melt mixing followed by hot press molding. The effect of fiber addition on some physical and mechanical properties was evaluated. Different process parameters (e.g. mixing time, heating temperature and time, cooling time etc.) were established for good sample preparation The effects of fiber addition on some physical and mechanical properties were evaluated. The mechanical properties were studied via Universal Testing Machine (UTM). The density was increased with the increase of fiber addition. The tensile strength (TS) of fabricated product increased with the increase of fiber addition up to 10% (by wt.) and then decreased continuously. The elongation of fabricated composites was decreased with the increase of fiber addition continuously. The changes in the mechanical properties were broadly related to the accompanying interfacial bonding of HDPE coir composites (HDPECC). To observe the hydrophilicity of the prepared composites was evaluated by the water uptake properties. The interfacial bonding of the fiber and matrix of the coir fiber reinforced composites was studied via scanning electron microscope. It revealed that the introduction of short coir fiber led to a slightly improved mechanical stability of PP- Coir composites.

Critical length and interfacial strength of PALF and coir fiber incorporated in epoxy resin matrix

The several advantages of natural lignocellulosic fibers (NLFs), such as, economical, technical, environmental and social, make these fibers an alternative to replace synthetic fibers in composite materials. The application of NLF as reinforcements in polymeric composites has increased in many industrial sectors from civil construction to automobiles. This demands the characterization of promising fibers, such as those extracted from leaves of pineapple (PALF) and the mesocarp of coconut fruit (coir fiber), for possible application in composites. In the present work, pullout tests were performed to compare the interfacial adhesion with epoxy resin of these two fibers that have greatly different characteristics. Results showed a critical length 70% higher for the coir fiber in comparison to PALF and a interfacial strength 3.5 times smaller, which indicates stronger adhesion of PALF with epoxy resin. This may be justified by the distinct morphological aspects, particularly the rougher surface of PALF. Mechanical tests were also performed in both coir fiber and PALF composites. In these tests, it was observed the superiority of mechanical properties for the composite reinforced with 30vol% of PALF. Additionally, ballistic tests were carried out. In this evaluation, composites were used in a MAS type III against the 7.62mm ammunition. The results revealed a relatively low depth of penetration (18.2mm) for the MAS with PALF composite as well as a depth of penetration (31.6mm) for MAS with coir composite, both considered efficient according to the personal body armor standard. Therefore, all these results highlight the potential of these fibers as polymer composites reinforcement in ballistic armors.

Preparation and Testing of Composites using Waste Groundnut Shells and Coir Fibres

Composite materials are now-a-days replacing the traditional materials because of its superior properties such as high tensile strength, low thermal expansion and high strength-to-weight ratio. Natural fibre composites such as groundnut shell polymer composites and coir composites have become more attractive due to their high specific strength, light weight and biodegradability. This work attempts to study particulate natural fiber based epoxy composites. It is concerned with the preparation and testing of composite materials from groundnut shell fibres and coir fibres along with binder and epoxy resins. The groundnut shells are chemically washed, cleaned and then dried in sunlight. The dried shells are then grinded to particle sizes of 1 mm, 1.5 mm, 2 mm and the epoxy resins are added in 70:30 ratio by weight to the fibres in a 12 mm thick mould and different flat square-shaped composites are obtained. Specimens of different particle sizes are cut into standard dimensions as per ASTM for different mechanical and moisture absorption tests. The results thus obtained are relatively compared between groundnut shell and coir fiber composites so as to suggest suitable applications. In general, the coir fibre composites are found to be comparatively better than groundnut fibre composites particularly considering the mechanical properties.

Effect of maleated natural rubber on tensile strength and compatibility of natural rubber/coconut coir composite

Natural rubber (NR)/coconut coir (CF) composites were fabricated using co-rotating twin screw extruder with maleated NR (MNR) used as compatibilizer. The MNR was produced at three level of maleic anhydride (MA), and analyzed qualitative and quantitatively using FTIR and titration technique. Analysis on MNR using FTIR and titration methods showed that MA was grafted on NR chain at different percentage (0.76, 2.23, 4.79%) depended on MA concentration. Tensile strength data showed the best tensile strength was produced at 7 phr of MNR with 1 phr of MA level in MNR resulting 16.4 MPa. The improvement of compatibilized samples were more than 300% compare to uncompatibilized composite attributed to better interfacial bonding. The improvement on tensile strength was significantly influenced by MNR level and amount of MA added to produce MNR, as well as their interaction. The optimum conditions for producing NR-CF composite were predicted at 6.5 phr of MNR level with 1 phr of MA concentration added in MNR production, regardless screw rotation settings. Results from verification experiments confirm that developed model was capable of describing phenomena during composite preparation. Morphology analysis using scanning electron microscopy shows smooth covered fiber in compatibilized samples than that of without MNR. The morphology also showed less voids on compatibilized samples attributed to better interfacial bonding leading to tensile strength improvement.