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Coir fibre, derived from the husk of coconuts, is a natural resource and they are biodegradable and renewable. By incorporating them, any product can become more lightweight and durable, meeting the global desire for eco-friendly and efficient designs. This study has the potential to significantly alter the design of components such as switches and enclosures and it has an international research impact on engineering applications. Coir fibres and Hexagonal-Boron Nitride (h-BN) possess superior mechanical, thermal and physical qualities when reinforced with polymers. Hence novel study is carried out to examinecoir fibre/h-BN reinforcement in epoxy polymer composites. Response Surface Methodology via Box-Behnken Design (BBD) is utilized to investigate the mechanical properties such as Tensile Strength, Impact Strength and Young’s Modulus of coir fibre/h-BN reinforced epoxy polymer composite. The effect of input parameters onresponse is evaluated through regression equation and analysis of variance by using statistical Minitab software. The response optimization represents the maximum Young’s modulus (1597 MPa) by combining coir fibre (5 wt%), Coir fibre powder size (75 μ m) and h-BN (1 wt%). The response optimization portrays the maximum Ultimate Tensile strength(36.83 MPa) by combining coir fibre (1 wt%), coir fibre powder size (220 μ m) and h-BN (3.78 wt%). The response optimization reveals the maximum Impact strength (98.35 J m ^−2 ) by combining coir fibre (5 wt%), coir fibre powder size (225 μ m) and h-BN(1 wt%). This work emphasises the use of composite materials that are environmental friendly in a variety of industries such as automotive, electrical, etc.

The study investigates the potential of coconut husks in purifying biogas, a common issue in the use of biogas due to the high costs and environmental impact of expensive purification technologies. The study used an experimental setup generating biogas from kitchen waste and analysed its composition using an industry-standard biogas analyser. Coconut husks could remove hydrogen sulphide (H2S), with a high percentage removal efficiency of 54% at a column length of 0.5 m from the inlet. Based on the results, 2 kg of coconut husk could purify 837 L of biogas, with a removal efficiency of approximately 62%, before exhaustion. This suggests that coconut husks can be used in biogas purification to remove H2S, which is the most challenging component as it can corrode metal parts when used at high concentrations above 750 ppm. Further research is needed on large-scale purification using coconut husks at high pressure to allow more gas adsorption by the purification media.

The study investigates the potential of coconut husks in purifying biogas, a common issue in the use of biogas due to the high costs and environmental impact of expensive purification technologies. The study used an experimental setup generating biogas from kitchen waste and analysed its composition using an industry-standard biogas analyser. Coconut husks could remove hydrogen sulphide (H2S), with a high percentage removal efficiency of 54% at a column length of 0.5 m from the inlet. Based on the results, 2 kg of coconut husk could purify 837 L of biogas, with a removal efficiency of approximately 62%, before exhaustion. This suggests that coconut husks can be used in biogas purification to remove H2S, which is the most challenging component as it can corrode metal parts when used at high concentrations above 750 ppm. Further research is needed on large-scale purification using coconut husks at high pressure to allow more gas adsorption by the purification media. [ABSTRACT FROM AUTHOR]

Sandwich panels (modular panels) promote optimal solutions to some major issues prevailing in the construction industry such as increased energy consumption by building elements, excessive disposal of constructional waste and unproductive time spent during construction. Hence, the inclination towards sandwich elements has been increased vastly deviating from conventional building construction materials and methods. However, the potentiality of using locally available natural materials for the development of sandwich panels is a salient sustainable approach that needs to be addressed. This study evaluates the current and potential materials used in modular panels and key properties of sandwich panels including mechanical, thermal insulation, and sound insulation properties. Moreover, various test methods followed, and standards specified to investigate the mechanical, thermal and acoustic insulation properties are also discussed. The possibility of using coconut fibre as a locally available natural alternative core material to polyurethane core of sandwich panels has been evaluated using simulations based on the material properties obtained from literature. The study identifies coconut fibre as a potential alternative core material for sandwich roof panels as it reflects nearly similar thermal behaviour to polyurethane.

Calcined seashell (CSS) powder and treated coir fibre (CF) are well-established additives for reinforcing poor soils. However, the absence of specific mix designs to optimize the mix additives makes it difficult to predict their combined effect on improving the mechanical behaviour of poor soils. This research explores the use of response surface methods to find the optimal proportions of CSS and CF for enhancing the mechanical properties of a tropical residual soil. This study uses a combination of Analysis of Variance (ANOVA) and regression models to examine how the independent variables of the CSS content, CF content, and curing duration influence the responses of the Unconfined Compressive Strength (UCS), Flexural Strength (FS), and Indirect Tensile Strength (ITS). The findings show that the optimal mix of 9.06% CSS, 0.30% CF, and 12 days of curing significantly improved the UCS, FS, and ITS by roughly six, four, and three times, respectively. Microstructural analysis revealed that the formation of calcium-aluminate-hydrate and calcium-silicate-hydrate are the primary components responsible for the enhanced mechanical properties of the treated soil. [ABSTRACT FROM AUTHOR]

In this study, the microstructure, chemical composition, linear density, tensile modulus of elasticity, tensile strength and strain at break of coir fibres exposed to saturated Ca(OH) 2 solution (i.e., pH = 12.5) up to 24 weeks were investigated. Different fibre surface modification methods were applied on coir fibres to investigate their effectiveness on the long-term tensile performance of coir fibres. The surface modification methods included treating fibres in: (1) boiling water, (2) 0.01 g/ml NaOH solution, or (3) 5% H 2 O 2 solutions for 2 h, respectively. Coir fibres after modifications were then immersed in Ca(OH) 2 solution up to 12 weeks and tested in tension at time intervals of 0, 4 and 12 weeks, respectively. Coir fibres without surface treatment were also immersed in both Ca(OH) 2 solution and distilled water up to 24 weeks and tested in tension at intervals of 0, 2, 4, 12 and 24 weeks, respectively. Statistical significance test was used to discuss the change in the fibre linear density and tensile properties. The results showed that all the surface modifications selected had no significant influence on the linear density of coir fibres. Thermogravimetric analysis and Fourier-transform infrared spectroscopy confirmed the decomposition of hemicellulose of coir fibres and the generation of CaCO 3 on the fibre surface after exposure to Ca(OH) 2 solution. The average tensile strength of the coir fibre reduced to 74% and 66% respectively after 12 and 24 weeks exposure in the Ca(OH) 2 solution in comparison with that of fibre exposed in distilled water. The corresponding average ultimate strain also reduced to 53% and 27% at 12 and 24 weeks. No obvious tendency could be identified in the average tensile E-modulus of coir fibre after long-term exposure. Through scanning electron microscopy, it was found that failure along the microfibrils and tensile failure of the microfibrils were the two main failure modes of coir fibre under tension. Surface modification with NaOH changed the permeability of coir fibre surface. Tylosis decomposition occurred due to H 2 O 2 solution modification. Neither H 2 O 2 solutions nor boiling water modification had significant influence on the tensile behaviour of coir fibre. [ABSTRACT FROM AUTHOR]

Abstract Natural fibre reinforced polymer composites are often a better substitute to man-made fibre reinforced polymer composites because of their wide availability, economical, recyclability and biodegradability. In this paper, natural fibre reinforced polymer composites are made using coir/ fly ash as reinforcements. Influences of polymer types, natural fibre (coir) length and wt. % of fly ash on tensile and flexural behaviors are investigated. General purpose resin, Vinyl ester and Isophthalic resin are the different polymers used in making samples. The samples are prepared according to Taguchi Design of Experiments using L9 orthogonal array. To explore the significance of participating factors such as polymer type, natural fibre (coir) length and wt. % of fly ash on the tensile and flexural behaviors, ANOVA is implemented. Regression equations reveal that the type of polymer influences tensile and flexural behaviors more than that of natural fibre (coir) length and wt. % of fly ash.

Vacuum oven heat treatments were done to enhance the properties of coir fibre for improved performance in composites. Their effects on the mechanical properties of coir fibres were investigated. As received (AR) coir fibres were subjected to heat treatment temperatures of 80 oC and 160 oC for 6 hours at each temperature in a vacuum oven. The effects of the heat treatment temperature on AR coir fibres were statistically analyzed using ANOVA, F-tests, Fisher Pairwise grouping and Fisher Individual Tests for Difference of Means (FITDM) with Minitab-18 Software. This was done to determine the significance of these heat treatments on the tensile properties of AR coir fibres. Fisher Pairwise grouping and FITDM show that strength and elongation of AR coir fibres differed significantly from coir fibres heat-treated at 80 oC. The tensile strength of AR coir fibres was found to be, respectively, 49% and 24% lower than coir fibres treated at 80 oC and 160 oC. The stiffness of coir fibres (AR) was found to significantly increase after heat-treating at 160 °C, while the elongation at break of AR was 44% higher. The strength distributions obtained from the tensile test data were subjected to two-parameter Weibull statistics. AR coir fibres displayed Weibull moduli that were 16% and 56% higher than coir fibres treated at 80 oC and 160 oC, respectively. SEM was conducted on the samples to delineate the morphological changes affecting the properties of coir fibres. [ABSTRACT FROM AUTHOR]

Vacuum oven heat treatments were done to enhance the properties of coir fibre for improved performance in composites. Their effects on the mechanical properties of coir fibres were investigated. As received (AR) coir fibres were subjected to heat treatment temperatures of 80 oC and 160 oC for 6 hours at each temperature in a vacuum oven. The effects of the heat treatment temperature on AR coir fibres were statistically analyzed using ANOVA, F-tests, Fisher Pairwise grouping and Fisher Individual Tests for Difference of Means (FITDM) with Minitab-18 Software. This was done to determine the significance of these heat treatments on the tensile properties of AR coir fibres. Fisher Pairwise grouping and FITDM show that strength and elongation of AR coir fibres differed significantly from coir fibres heat-treated at 80 oC. The tensile strength of AR coir fibres was found to be, respectively, 49% and 24% lower than coir fibres treated at 80 oC and 160 oC. The stiffness of coir fibres (AR) was found to significantly increase after heat-treating at 160 °C, while the elongation at break of AR was 44% higher. The strength distributions obtained from the tensile test data were subjected to two-parameter Weibull statistics. AR coir fibres displayed Weibull moduli that were 16% and 56% higher than coir fibres treated at 80 oC and 160 oC, respectively. SEM was conducted on the samples to delineate the morphological changes affecting the properties of coir fibres.

Filtration of Particulate Matter (PM) 2.5 and PM 10 particles are focused by the filters used in Heating, Ventilation and Air Conditioning (HVAC) systems. Synthetic fibres/filaments are widely used to construct the filters for air conditioning filters and cleanroom filters which is not biodegradable. Natural fibres are easily biodegradable, exhibit better filtration characteristics as like synthetic fibres. In this research, alkali-treated coir fibres are used to construct the filter for filtering the particle range of 1.0 µm to 10 µm. Box- Behnken experimental design was used for the experimental plan and the experiments were conducted to construct the filters. The change in fibre properties by alkali-treatment was observed and the treatment with 5% and 10% alkali increases the crystallinity index of fibres. The influence of independent variables on the performance of developed filters was analyzed in detail. 5% NaOH treated fibre sample with 20% resin proportion and 60 g fibre content in the unit area was identified by a quality factor as the best combination of independent variables for constructing filter. [ABSTRACT FROM AUTHOR]

Natural fibres find their application as a reinforcing agent for polymer composites to obtain parts with improved mechanical properties. Manufacturing of non-metallic products is incorporated with natural fibres for better strength and to reduce cost. Rotational moulding is a process used for the manufacturing of hollow plastic products, especially water tanks, plastic fuel tanks, barrels, kayaks, refrigerated panels, etc. Incorporation of natural fibres to reinforce polymers in rotational moulding process is a tedious task; since there is no control over fibre and polymer powder mixture, which is rotating bi-axially, it may lead to fibre agglomeration. The present work investigates the mouldability of linear low density polyethylene composites with tampico and coir fibre as the reinforcement agents using a bi-axial rotomoulding machine. NaOH-treated fibres with 5, 10 and 15% by weight have been added to the linear low density polyethylene matrix, and the composites were prepared by rotational moulding process. Mechanical properties such as tensile strength, flexural strength, impact strength and hardness have been investigated. Dynamic mechanical behaviour such as storage modulus, loss modulus and tan δ of the different composites has been investigated with dynamic mechanical analyser. Fractured surfaces were examined qualitatively with the help of a scanning electron microscope for determining the interfacial properties and fibre adhesion between the fibres and the linear low density polyethylene matrix. [ABSTRACT FROM AUTHOR]

Coir fibre and pith are eco-friendly material used in the preparation of composites. Coir fibre and coir pith were treated with sodium hydroxide to study the effect of alkali for prolonged exposure on its properties. Fibre and pith were treated with different concentrations of NaOH from 5% to 30% for 24 hours at room temperature. Alkali treatment removes the impurities and the expose the crystalline cellulose and to enhance the surface properties. The alkali-treated coir fibre and pith were characterized by Scanning electron microscopy for morphology, X-ray diffraction for crystallinity index, thermogravimetry for thermal stability, Fourier-transform infrared spectroscopy for structural changes. The chemical composition was analysed for both fibre and pith. Physical properties such as bulk density, particle density and porosity were determined for pith. After alkali treatment, the properties (physical and chemical) of the treated fibre (5% to 20%) has been enhanced. For coir pith the properties has been diminished. Untreated/treated coir fibre/pith filter (CFP) were developed to study the removal of heavy metal ions from the waste water, where untreated (CFP) as a control. The removal efficiency of the developed CFP filter for heavy metal ions were determined by Inductively coupled plasma - optical emission spectrometry (ICP-OES). 5% CFP filter exhibited higher efficiency for removal of heavy metal ions. [ABSTRACT FROM AUTHOR]

This paper provides a comprehensive review on the research of coir fibre and coir fibre reinforced cementitious composite (CFRC) in the past 20 years. In the first part, the extraction process, morphology, density, chemical composition, and tensile performance of coir fibres are discussed. Then, the pull-out performance, physical properties (i.e., density, thermal and acoustic insulation), short- and long-term properties (i.e., compressive, flexural, impact, and dynamic performance) of CFRC are reviewed. Existing modification methods (i.e., cementitious matrix and fibre surface modifications) to improve the bond and mechanical behaviour of CFRC and the practical application of CFRC in construction are presented. Future perspectives of CFRC studies are highlighted, including the validation of existing models (i.e., for the prediction of coir tensile strength as well as bond strength and total energy of CFRC), further investigations on long-term, seismic, fire performance of CFRC, and the use of coir fibre in geopolymer and coconut shell aggregate concrete towards practical application. [ABSTRACT FROM AUTHOR]

This paper addresses the potential alternative green construction technology utilising agricultural waste. Research on precast self-compacting concrete beam (PSCC-B) incorporating banana skin power (BSP) as cement replacement, and coir fibre (CF) as filler, was conducted. In this research, the materials and mechanical properties of the self-compacting concrete (SCC) with added BSP and CF were investigated. The study encompasses two trial mix comprising different percentages of BSP and CF. Two (2) control beams and six (6) beams containing various percentages of BSP and CF were cast and tested under a four-point loading test with a shear span-to-depth ratio of 1.7. From the results obtained, it was observed that an innovative mix ratio of SCC with 0.4% BSP and 0.5% CF enhances its compression strength and tensile strength by up to 7% and 59%, respectively. Likewise, modulus of elasticity for SCC with various ratios of BSP and CF recorded values in the range of 31–43 GPa, which is similar to or higher than most normal concrete. The flexural test results showed that PSCC-B with 0.4% BSP and 0.5% CF attained the highest ultimate flexural load, slightly lower deflection, and less crack width compared to the other beams. [ABSTRACT FROM AUTHOR]

This paper addresses the potential alternative green construction technology utilising agricultural waste. Research on precast self-compacting concrete beam (PSCC-B) incorporating banana skin power (BSP) as cement replacement, and coir fibre (CF) as filler, was conducted. In this research, the materials and mechanical properties of the self-compacting concrete (SCC) with added BSP and CF were investigated. The study encompasses two trial mix comprising different percentages of BSP and CF. Two (2) control beams and six (6) beams containing various percentages of BSP and CF were cast and tested under a four-point loading test with a shear span-to-depth ratio of 1.7. From the results obtained, it was observed that an innovative mix ratio of SCC with 0.4% BSP and 0.5% CF enhances its compression strength and tensile strength by up to 7% and 59%, respectively. Likewise, modulus of elasticity for SCC with various ratios of BSP and CF recorded values in the range of 31–43 GPa, which is similar to or higher than most normal concrete. The flexural test results showed that PSCC-B with 0.4% BSP and 0.5% CF attained the highest ultimate flexural load, slightly lower deflection, and less crack width compared to the other beams.

Many researchers have investigated alternative sources to overcome the problem of conventional building material polluting the environment by the development of green self-compacting concrete in the construction industry. The best alternative solution is to utilise non-conventional construction materials like agricultural wastes. Meanwhile, self-compacting concrete (SCC) is considered as high strength as well as high-performance concrete. The demerits, which include tensile and flexural strength, can be improved by incorporating coir fibres. The utilisation of coir fibres also modifies self-compacting concrete performance after cracking and improves the toughness. This study defines an experimental investigation of the mechanical properties of self-compacting concrete containing coir fibres (CF) with different percentages being 0%, 0.2%, 0.5%, 1%, and 1.5% at 7- and 28-days water curing. The mechanical properties include the slump flow and compressive and tensile strength were examined. The outcomes demonstrated that a required slump flow for self-compacting concrete was achieved using coir fibres up to 1%, beyond which it reduced the slump significantly. The length of fibre and proportion of fibres directly affected the workability. The compressive strength was 10% to 15% enhanced with the incorporation of coir fibres up to 0.5%; after that, the strength was slightly reduced, and tensile strength was 30% to 50% improved compared to conventional self-compacting concrete up to 1% of coir fibres incorporation in the SCC mix, after which it rapidly reduced.

Cement stabilised rammed earth (CSRE) is used in the construction of load bearing walls. CSRE elements under compressive loads experience sudden catastrophic shear failures. Such brittle failures shall be avoided in the CSRE structures. The addition of short discrete randomly oriented fibres to CSRE can help avoid such catastrophe failures, where the fibres can bridge across the crack and help inhibit the crack propagation. The paper deals with studies on the effect of coir fibre reinforcement on the behaviour of CSRE under compression. The influence of fibre volume fraction, cement content and moisture content on the strength and stress–strain characteristics of CSRE has been investigated. Five fibre volume fractions (VF), 0.0, 0.5, 1.0, 1.5 and, 2.0%, two cement contents (7 and 10%), and two moisture conditions were considered. The compressive strength of fibre reinforced CSRE increased by 10–30% for 1% VF. The strain at peak stress and the failure strains have significantly increased with the addition of fibres indicating the improved ductility and the post peak response of the material. The energy absorption capacity of CSRE increased by 2–5 times for an increase in the fibre volume fraction from 0 to 2%. The sudden catastrophic shear failures observed in the cement stabilised rammed earth under compression can be eliminated by the addition of short randomly oriented coir fibres. The fibre volume fraction of 1% is the optimum. [ABSTRACT FROM AUTHOR]

This study explores the possibility of using sustainable materials in the form of fly ash as a precursor in alkali activation (AA) reactions, as well as coir fibres as discrete reinforcement. For enhancing the longevity of fibres in an alkaline environment and improving the mechanical performance of the soil–fibre composite, an effort was made in this study to physically coat the natural fibre surface with linseed oil and turpentine oil. The effect of surface treatment on coir fibres was initially analysed by field emission scanning electron microscopy and energy dispersive x-ray tests. To evaluate the effects, unconfined compressive strength, indirect tensile strength, and flexural strength tests were performed at 7 and 28 days of curing on AA-treated soil reinforced with treated and untreated coir fibres. The test results demonstrated that treated fibres significantly enhanced the mechanical properties of the AA-treated soil in terms of peak stress and post-peak behaviour. [ABSTRACT FROM AUTHOR]

Purpose: In this work, coir fibre with varying fibre content was selected as reinforcements to prepare polymer-based matrices and the problem of reduced fibre-matrix interfacial bond strength has been diluted by chemical treatment of coir fibres with alkali solution. Design/methodology/approach: The effect of fibre loading, solution concentration and soaking time on the impact strength of the composites were analyzed using statistical techniques. Response Surface Methodology (RSM) approach was used to model and optimize the impact properties of coir-polyester composites. Findings: The impact strength of coir fibre reinforced polyester composite depends mainly on the fabrication parameters such as fibre-polyester content, soaking time, concentration of soaking agent and adhesive interaction between the fibre and reinforcement. Research limitations/implications: The mechanical properties of any coir polyester composite depend on the nature bonding between the fibre and reinforcement. The presence of cellulose, lignin on the periphery of any natural fibre reduces the bonding strength of the composite. This limitation is overcome by fibre treatment over sodium hydroxide to have better impact properties. Practical implications: Now days, natural fibre reinforced composites are capable of replacing automotive parts, subjected to static loads such as engine Guard, light doom, name plate, tool box and front panels etc. These materials can withstand any static load due to its higher strength to weight ratios. Originality/value: The effect of fibre loading, solution concentration and soaking time on the impact strength of the composites were analyzed using statistical techniques. Response Surface Methodology (RSM) approach was used to model and optimize the impact properties of coir-polyester composites. The impact strength of NaOH impregnated coir fibre reinforced polyester composites was evaluated. [ABSTRACT FROM AUTHOR]

Now-a-day's lot of researcher interest is directed towards the conversion of bioresources (waste) to carbon-based materials for meeting the demand of sustainable energy. In the present study, we have utilized waste coir fibres for the synthesis of graphene oxide and its derivatives. Microscopic investigation of coir fibre indicates that silica microspheres assembled in a regular pattern inside the cellulose matrix of coir fibre. Here, we have attempted to make water-soluble silica-based compound via reaction of coir with alkali metal hydroxide. Further, heating of water-soluble silicates-cellulose mixture leads to the formation of porous graphene oxide having high specific surface area (1114 m2/g). Doping of sulphur and nitrogen has been done via the chemical route, which leads to enhancement in electronic conductivity. The electrochemical study of bare and doped graphene oxide have been carried out using electrochemical work station. The electrochemical study confirms that nitrogen-doped graphene oxide has highest specific capacitance (278.6 F/g) as compared to bare graphene oxide (166.1 F/g) and sulphur doped graphene oxide (199.2 F/g) at 1 A/g discharge current because of high charge carrier density in nitrogen-doped graphene oxide (9.7 × 1014 cm−3). The galvanic charge-discharge (GCD) stability shows ∼82% capacitance retention after 2000 GCD cycle at 3 A/g of nitrogen-doped graphene. The above approach for conversion of low-value coir fibre to high-value energy storage material (graphene oxide) would certainly be interest of the researchers working in the field of energy storage, environmental pollution control, waste management, materials science, sustainable chemistry and engineering for achieving the goal of cleaner production technologies for better environmental sustainability. Image 1 • Investigation of coir fibre microstructure using an electron microscopy technique. • Design of chemical process to convert coir fibre into porous graphene oxide. • Sulphur/Nitrogen being doped for increasing the conductivity of graphene oxide. • N-doped graphene shows the highest specific capacity (278.6 F/g at 1 A/g). [ABSTRACT FROM AUTHOR]