Treatment Of Natural Fibers Research Articles

Polyurethane derived from castor oil reinforced with long cotton fibers: Static and dynamic testing of a novel eco-friendly composite material

A novel eco-friendly composite material made of polyurethane derived from castor oil reinforced with long cotton fibers was developed. A set of comparative analyses comprising static and dynamic tests was established using specimens made of castor oil-based polyurethane reinforced by glass fibers, and epoxy reinforced by glass and cotton fibers. The manufacturing method and estimation of fiber volume fraction of the specimens were described in detail. Tensile and flexural tests were performed to evaluate the mechanical performance of the novel laminate. Fractographic post-mortem examinations assessed the quality of the fiber–matrix interaction and allowed direct observation of the failure modes. Surface treatment of natural fibers appears necessary to improve the adhesion of the natural fibers to the matrix. Dynamic responses are discussed, considering natural frequencies and modal damping coefficients. In this context, the potentialities and the limitations of using the novel eco-friendly composite material as structural parts are discussed.

Extraction and Characterization of Natural Fibres from Plantain (Musa paradisiaca) Stalk Wastes

Plantain stalks obtained from solid waste stream of Ganmo market in Ilorin was used in this study. Natural fibres extraction from waste plantain stalk was achieved using biological retting methods. The natural fibre was rented from the waste stalk after 24 days of soaking in water. The extracted fibres were exposed to 2, 4 and 6% alkali solution (NaOH) treatment for two hours, washed and dried in the oven for 7 hours. Elemental analysis of raw plantain fibres showed the presence of elements like Indium, Potassium, Silicon and Calcium among others. Tensile strength analysis of the fibres, for single fibre strands showed that the 2% treated fibre showed distinctly promising potential with the highest tensile characteristics of young modulus, stress at break and force at peak of 52864.366N/mm2, 5398.536N/mm2 and 2.650N, respectively. Evaluation of the chemical composition of plantain by FTIR spectroscopy indicated that treatment of natural fibres using NaOH beyond 2% have a negative impact on the plantain fibre properties. Through alkali exposure, the fibre configuration presents small variations in composition. It is consequently apparent that alkali treatment with concentration of less than 2% NaOH is sufficient to remove hemicelluloses and to obtain the optimum tensile effect.

Imapact of Chemical Treatment and Bonding Agents on Mechanical Behavior of Polymer-Coir/Banana Natural Cellulose Fiber Hybrid Composite

Currently day by day most of the mechanical and supporting structures being replaced with the composite materials due to their dominating mechanical strength to weight ratio. The properties of the composite material depends on the type of the fiber i.e., natural or synthetic, size of the fiber (short or long), type of the resin etc and so on. The specialized properties are in demand by most of the industries can be achieved by using the hybrid polymer composites. The chemical or alkali treatment of natural fibers affects the properties of the composite material. The bonding agents between different compounds in the composite material also play the vital role in changing the properties of the composite material. In the present work, the effect of the chemical treatment and coupling agents on the properties of the hybrid composite material were studied. Sodium hydroxide is used as chemical treatment agent and maleic anhydride polypropylene (MAPP) used as coupling agent. Coir/banana short fiber hybrid composite with polypropylene matrix is used as composite material. The effects of these agents on the tensile strength, Young’s modulus, flexural strength, flexural modulus and impact strength have been studied.

Effect of Ultraviolet Exposure to the Cylindrica (L.) Beauv. Fiber Characteristics

This article explains usage of the ultraviolet irradiation method on Beauv cylindrical (L) imperata fibers as a new way of natural fiber treatment, based on the absorption of ultraviolet rays containing other elements that lead to lignin degradation, which enhances natural fiber strength. Using the ultraviolet exposed fiber method with intervals of 10, 20, 50, and 100 hours, each treatment was tested with scanning electron microscope-energy dispersive spectroscope. The authors found that the treatment resulted in an increase in the fiber’s tensile strength. The results of fiber treatment with 50-hour irradiation produced a fiber with a tensile strength of 130.2 MPa. Our method allows an increase in the AL2O3 element, which indicates an increase in fiber tensile strength of 130.2 Pa. An evaluation of the effectiveness of the new method can be seen in the scanning electron microscope-energy dispersive spectroscope test results. The Imperata Cylindrica (L) Beauv fiber surface roughness test results showed an increase in surface roughness to 1.47 μm resulting from the 50-hour ultraviolet treatment. With this roughness, the adhesion between the fiber and epoxy resin increases. This increased fiber tensile strength and surface roughness, as a result of ultraviolet light treatment, offers the potential for its use as a composite reinforcement.

Fabrication and Characterization of Microcellular Polyurethane Sisal Biocomposites.

In this study, microcellular polyurethane (PU)-natural fiber (NF) biocomposites were fabricated. Polyurethanes based on castor oil and PMDI were synthesized with varying volume ratios of sisal fiber. The effect of natural fiber treatment using water and alkaline solution (1.5% NaOH) and load effect were investigated. Biocomposites were mechanically and physically investigated using tensile, viscoelasticity, and water absorption tests. The interfacial adhesion between PU and sisal fiber was studied using SEM. Short NF loads (3%) showed a significant improvement in the mechanical properties of the PU-sisal composite such as modulus of elasticity, yield and tensile strength up to 133%, 14.35 % and 36.7% respectively. Viscoelastic measurements showed that the composites exhibit an elastic trend as the real compliance (J’) values were higher than those of the imaginary compliance (J’’). Increasing NF loads resulted in a decrease of J’. Applying variable temperatures (120–80 °C) caused an increase in the stiffness at different frequencies.

A review on the properties of natural fibres and its bio-composites: Effect of alkali treatment

Due to the dominating advantages of natural fibres such as biodegradability, eco-friendliness, nominal cost, low density and high specific strength, they are being used opposite to synthetic fibres in many industrial applications. Despite many advantages, these fibres face some limitations such as higher moisture uptake, quality variations, low thermal stability, and poor compatibility with polymeric matrix. To overcome these limitations, chemical treatments of these fibres were found to be the most suitable method to improve adhesion with polymers, increase their strength and water absorption resistance, and improve their composite properties also. Among chemical treatments, alkali treatment is the most widely used and versatile surface modification method of the natural fibres. A good number of research works have been carried out on effect of alkali treatment on the properties of natural fibres and its composites, which motivated for this review. In this paper, the effect of alkali treatment on the properties of natural fibres has been reviewed. In addition, the physical and mechanical properties, thermal analysis and tribological behaviour of its biocomposites are also reviewed. It was concluded that alkali treatment of natural fibres could provide enhanced properties of various bio-composites up to a great extent.

Morphology, thermal and mechanical properties of extruded injection molded kenaf fiber reinforced polypropylene composites

The aim of this study is to explore the effect of coupling agent and surface treatment of natural fibers on the correlations among structural, thermal and mechanical behavior of injection molded composites. Polypropylene (PP)-based composites reinforced with kenaf fiber as a biodegradable filler were fabricated. Kenaf composites were prepared by adding 10, 20, 30, and 40 wt% of kenaf fibers into the matrix using melt mixing and injection molding considered as a simple, scalable, conventional, and efficient process, that is. Different concentrations of NaOH were applied to modify kenaf fibers. The scanning electron microscope (SEM), Fourier Transform Infrared (FTIR), and x-ray Diffraction (XRD) analysis were conducted in order to find the optimum concentration of NaOH for the chemical treatment and to study the morphology of the fabricated specimens. Maleic anhydride polypropylene (MAPP) was employed as the coupling agent. Moreover, the tensile, flexural and impact tests were conducted to evaluate the mechanical properties of the specimens. Results showed that by the incorporation of kenaf fibers of up to 40 wt%, the tensile and flexural strength significantly improved by 100% and 120%, respectively, with respect to those exhibited by the neat PP. It was shown however that the impact strength decreased by around 18%. Moreover, the results of thermal analysis using the differential scanning calorimetry (DSC) showed that the addition of kenaf fibers into the PP matrix increases the melting and crystallization temperature, and the degree of crystallinity. The XRD analysis of composites further confirmed the influence of fibers on the PP crystallization behavior. The results of this work can further extend the use of natural fiber-reinforced PP composites for structural applications such as automotive interior parts.

Synthesis and Characterization of Urea–Formaldehyde Eco-Friendly Composite Based On Natural Fibers

Present work explains the synthesis of urea–formaldehyde composites with Allo (Girardinia diversifolia) and cotton (Gossypium arboreum) fibers. Urea–formaldehyde resin was synthesized by condensation polymerization of urea and formaldehyde monomers. Cellulose fibers were extracted by various chemical treatments of natural fibers. Composites were prepared with neat and extracted cellulose from Allo and cotton fibers by solution casting method. Fibers and composites were characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), optical microscopy (OM), thermo-gravimetric analysis (TGA) and micro-indentation tests. Results showed that composite with treated Allo fibers had better morphological, mechanical and thermal properties than untreated Allo and cotton fibers.

Mechanical Properties of Unidirectional Flax Fabric-Reinforced Furan Composites: Effect of Alkaline Treatment and Silane Coupling Treatment

Composite materials based on bio-derived furan resin and natural fiber as reinforcing elements were studied. The purpose of this research is to improve the mechanical properties of this composite material by focusing on the natural fiber treatment methods. Unidirectional flax fabric was pretreated by alkaline treatment, silane coupling treatment, and the combination between alkaline and silane treatment before impregnating with furan resin. Three-point bending test, SEM observation, and ATR-IR analysis were carried out to evaluate the effects of treatment methods on the composite samples. Results reveal that the flexural strength of the composite was increased to 215MPa, 232MPa, 247MPa for alkaline, silane, and alkaline-silane treated composites respectively while the flexural strength of the untreated composite sample is 200MPa. SEM images show the effects of alkaline treatment on a single flax fiber at different treatment durations. The coupling of silane on the surface of flax fiber was confirmed by ATR-IR.

Effect of lye alkaline solution treatment on engineering properties of oil palm empty fruit bunches (EFB) fiber strengthen foamed concrete

Natural fibers have become attention-grabbing and interesting these days to be employed as an industrial material and structural material for rehabilitating of structures. Nevertheless, the natural fibers to matrix interface interactions with cement matrix remain a key issue in getting the desired mechanical properties. Treatment of natural fibers is crucial in improving matrix to filler adhesion, thus improving its mechanical properties. In this study, oil palm empty fruit bunches (EFB) fiber was studied for use as reinforcement materials for cementitious composites in foamed concrete. The effect of fiber treatment on mechanical properties of EFB fiber reinforced foamed concrete was investigated comprehensively. For lye-treated EFB fibers, these fibers were washed three times with tap water to eliminate unwanted debris, dusts and impurities and dried at room temperature for 48 hours. Lye chemical solution of 2%, 4%, 6%, 8% and 10% wt. concentration were prepared using distilled water and lye chemical pellets. For the 2% wt. concentration, 2 grams of lye chemical was dissolved in 100ml of distilled water which is equivalent to 100 grams. For the 4, 6, 8 and 10% wt. concentrations, 4 grams, 6 grams, 8 grams and 10 grams of lye were dissolved in 100ml of distilled water respectively. The EFB fibers were soaked in the prepared solutions for a period of 24-hours after which they were removed and thoroughly rinsed until a neutral pH of the rinsing solution was attained. A pH meter was used to determine the pH value of the solution after rinsing. Finally, the dried fibers were sealed in a plastic bag before the composite manufacturing to avoid atmospheric moisture contamination. From the results obtained through experimental works, it can be concluded that the lye treatment of the EFB fibers modifies the fibers adequately causing a variation in the axial compression and flexural properties of the foamed concrete. Above all, 6% lye concentration gave better mechanical properties and therefore is considered a better treatment concentration value in the range of 2% to 10% wt. for improving the mechanical properties of EFB reinforced foamed concrete.

Mechanical Property Evaluation of Hybrid Reinforced Epoxy Composite

Fibre reinforced polymer composites has been used in a variety of applications because of there many advantages such as relatively low cost of production, easy to fabricate, and superior strength. The use of natural fibre as reinforcement in polymer has gained importance in recent years due to the eco-friendly nature. Past studies show that only artificial fibres such as glass, carbon fibre, etc have been used in fibre reinforced plastic. Glass and other synthetic fibre reinforced plastic poses high specific strength. But their fields of application are very limited due to their inherent higher cost of production. In this study the chemical treatment of natural fibres are done with one percentage of NaOH and one percentage of sodium lauryl sulphate (SLS). The composites are developed with bamboo fibre / glass fibre /epoxy resin, caryota fibre / glass fibre/ epoxy resin , bamboo fibre + caryota fibre / glass fibre / epoxy resin, the property evaluated are tensile strength flexural strength, impact strength and water absorption. It was observed that the material treated with 1% of SLS possess high flexural strength and material treat with 1% NaOH possess high tensile strength. NaOH treated Bamboo caryota glass fibre mix offer better impact strength. The surface morphology study of the specimen has done after testing with help of scanning electron microscopy (SEM).

Mechanical, morphological, and thermogravimetric analysis of alkali-treated Cordia-Dichotoma natural fiber composites

ABSTRACTUsage of composites with natural fiber reinforcement is drastically increasing in recent times because of their low density, biodegradable nature, and low cost. However, natural fibers have certain core problems such as poor adhesion between the fiber and matrix and a relatively high degree of moisture absorption. Alkaline treatment of natural fibers is aimed at improving the adhesive strength so that effective stress transferability takes place in the composite. In the present work, Cordia-Dichotoma fibers were treated with sodium hydroxide (NaOH) and composites were prepared with different weight ratios of these fibers reinforced with epoxy. The prepared composites were tested for their tensile and flexural strengths (mechanical properties). Besides, for a comprehensive material characterization, IR spectroscopy (FT-IR), scanning electron microscope, and thermogravimetric analysis were carried out. This work investigates the influence of aforementioned NaOH treatment on thermal, mechanical, and morphological properties of the composite material.

Surface treatments of plant fibers and their effects on mechanical properties of fiber-reinforced composites: A review

The need of natural fiber-reinforced composites is increasing at very fast rate because of their ecofriendly production, decomposition, high specific strength, abundance, good physical and mechanical properties. Available literature reveals that past researchers have done a lot of work for the preparation and characterization of fiber-reinforced composites. While developing natural fiber composites, researchers encountered various problems like hydrophilic nature of natural fibers, incompatibility of natural fibers with matrix materials, thermal instability of natural fibers, and poor interfacial bonding between reinforcing phase and matrix phase. However, some of these problems can be solved to a greater extent by considering surface treatment of natural fibers before they are used in the preparation of fiber-reinforced composites. Thus, there is a need for understanding the effect of several surface treatments on the mechanical properties of fiber-reinforced composites. The aim of this paper is to put forth a comprehensive review on the effects of different surface treatments on the mechanical properties such as tensile strength, flexural strength, and impact strength and also interfacial shear strength of the fiber-reinforced composites.

Psidium guajava leaf extract-mediated synthesis of ZnO nanoparticles under different processing parameters for hydrophobic and antibacterial finishing over cotton fabrics

In recent times, treatment of natural fibres, like cotton, with antimicrobial finishing using nanoparticles has become increasingly high due to the possibility of anticipated property and their tuneable nature. In this study, using the phytoconstituents of leaf extract of Psidium guajava, Zinc acetate was reduced to obtain ZnO nanoparticles using three different synthesis routes namely sonication, wet-chemical and hydrothermal methods. To evaluate and get a broader understanding about the influence of processing parameter over the ZnO nanoparticles, physico-chemical, biological and photocatalytic property, a comparative assessment was performed. The ZnO nanoparticles were subjected to X-ray diffraction, particle size analysis and scanning electron microscope to ascertain its structure/morphology. The comparative studies reveal that hydrothermal method of ZnO synthesis yields smaller particle size (12 nm), with higher photocatalytic activity (94%), higher antibacterial activity against Escherichia coli (27.4 mm) and Staphylococcus aureus (29.3 mm) and lower structural defects comparing to ZnO synthesised via other methods of synthesis. Furthermore, the most effective ZnO nanoparticles (hydothermal method) was incorporated in chitosan and coated over the cotton fabric to functionalise cotton fabrics for better antimicrobial and water repellent property. Along with the same line, the ZnO nanocomposite coated fabrics exhibit better hydrophobic (157 ± 0.1°) (superhydrophobicity) and higher antibacterial activity (30.58 ± 0.3 mm (99%) (S. aureus) and 24 ± 0.5 mm (96%) (E. coli)), which could be attributed to ZnO particle size and favourable structural morphology. Thus, the study not only reveals the tuneable nature of the ZnO nanoparticles with respect to processing parameters and also shows the potential role in coating these nanoparticles over the cotton fabrics to impart an effective antimicrobial and hydrophobic finishing for biomedical applications.

Thermal Characterization of Alkali Treated Kenaf Fibers and Kenaf-Epoxy Composites

Chemical treatment of natural fibers is a well-defined means of mechanical property improvement in natural fiberreinforced composites. An understanding of mechanical and thermal properties in these media is essential for evaluating heat transfer, thermal degradation, and overall performance of these composites over their product lifetime. However, very little information is available illustrating the effect of such treatment on the thermal properties of kenaf composites. Also, no study to date has reported the thermal conductivity of individual kenaf fibers. This study reports the effects of fiber treatment (in 6 % NaOH) on thermal transport in unidirectionally oriented kenaf-epoxy composites and individual kenaf fibers. The effective thermal conductivities and thermal diffusivities of chemically treated fiber composites show a general increase over untreated fiber composites (0.210 to 0.232 W/m/K at 28 °C, 0.206 to 0.234 W/m/K at 200 °C). This improvement may be attributed to improved interfacial contact between the fibers and epoxy matrix shown in microstructural images after chemical treatment. The thermal conductivity of individual fibers was evaluated at room temperature using two techniques. Results from both techniques showed slight increases after chemical treatment (0.58±0.53 to 1.0±0.13 W/m/K and 1.2±0.54 to 1.6±0.28 W/m/K) but lacked statistical significance. Any improvement in surface crystallinity after chemical treatment does not appear to affect overall fiber thermal conductivity. A better understanding of thermal transport in kenaf fibers and composites enables better estimation of the performance of these composites in different applications. Moreover, the thermal conductivities of individual fibers are useful in understanding the fiber’s contribution to conduction in different fiber reinforcement configurations.

Effect of Maleic Anhydride-Modified Poly(lactic acid) on the Properties of Its Hybrid Fiber Biocomposites.

This work investigated the effect of maleic anhydride (MA)-modified poly(lactic acid) (PLA), which is melt-blended with different untreated and aqueous borax (BR)-treated hybrid oil palm empty fruit bunch fibers (EFBF)/Kenaf core fibers (KCF), and compression-molded into corresponding hybrid biocomposites. These hybrid systems includes BR-treated EFBF/BR-treated KCF reinforced MA-modified PLA i.e., BR(EFBF-KCF)-MAPLA, BR-treated EFBF/BR-treated KCF reinforced unmodified PLA i.e., BR(EFBF-KCF)-PLA, untreated EFBF/untreated KCF reinforced MA-modified PLA i.e., EFBF-KCF-MAPLA, and untreated EFBF/untreated KCF reinforced unmodified PLA i.e., EFBF-KCF-PLA respectively. Characterizations of the hybrid systems revealed that optimal mechanical, physical, morphological, thermal and dynamic mechanical properties were provided by the BR(EFBF-KCF)-MAPLA, resulting from improved interface adhesion, consequent of the synergistic influence of BR treatment of natural fibers, and the compatibilization effect provided by the MA-modified PLA. The grafting degree and efficiency of MA onto the PLA backbone was appreciable, as indicated by direct titration, and through monitoring using Fourier Transform Infrared Spectroscopy (FTIR); thus the MA-modified PLA facilitated the formation of strong interface adhesion with the BR-treated hybrid fibers. The BR(EFBF-KCF)-MAPLA showed promising properties for usage as a bio-inspired, and sustainable alternative fiberboard article.

Effect of Natural Fibers Surface Treatment and their Reinforcement in Thermo- Plastic Polymer Composites: A Review

In previous years natural fibers are frequently used to reinforce materials. The biodegradability is the main advantage of natural fibers. The disadvantage of using natural fibers in polymer composite material is their poor adhesion ability with a polymeric matrix which affects the various physical and mechanical properties of the composite material. To overcome this disadvantage, the surface of the natural fibers needs to be modified so that a good fiber-matrix adhesion can be established. The various treatment methods such as physical treatment and chemical treatment methods for the improvement of fiber-matrix adhesion have been discussed in this paper. So the overall objective of this review paper is to highlight the previous and recent studies related to the surface treatment of natural fibers and their reinforcement in thermoplastic polymer matrix composites. The improvement in various properties specifically mechanical properties by reinforcing these fibers into thermoplastic polymer matrix composites has also been reported in this paper. Keywords: Fibers, surface modification, composites, polyethylene, polypropylene & PVC.

Hydrophobic treatment of natural fibers and their composites—A review

There is a growing interest in the development of natural fiber-reinforced composites, most likely due to their wide availability, low cost, environment friendliness, and sustainability. The market size for natural fiber-reinforced composites is projected to reach $5.83 billion by 2019, with a compound annual growth rate of 12.3%. The composite materials reinforced with wood, cotton, jute, flax or other natural fibers fall under this category. Meanwhile, some major factors limiting the large scale production of natural fiber composites include the tendency of natural fiber to absorb water, degradation by microorganisms and sunlight and ultimately low strength and service life. This paper has focused to review the different natural fiber treatments used to reduce the moisture absorption and fiber degradation. The effect of these treatments on the mechanical properties of these composites has also been summarized.

Surface Modification of Natural Fibers: A Review

In recent years there have been several attempts to replace synthetic fibers with natural fibers in fiber reinforced composites, due to increasing environmental awareness and depletion of oil resources. The fact that natural fibers are available cheaply and in abundance, being biodegradable and low density, has motivated many researchers throughout the world to explore their application potential in various industrial sectors. However, natural fibres also have some limitations such as high moisture absorption and subsequent swelling and degradation, poor chemical and fire resistance, high dispersion of mechanical properties, poor interfacial interactions with polymeric or cementitious matrices, etc. Therefore, there is a huge concern to modify the surface of natural fibers through various techniques, in order to overcome their inherent drawbacks and to successfully utilize these materials in various applications. This paper presents a review of existing research studies focused on the surface treatment of natural fibers and the use of nanocelulose, a natural nanofiber, for their application in composite materials.

A new eco-friendly chemical treatment of natural fibres: Effect of sodium bicarbonate on properties of sisal fibre and its epoxy composites

Several researchers have shown how sisal fibres possess remarkable tensile properties that yield them good candidates as reinforcement in biocomposite materials.This work aims to evaluate the effect of an eco-friendly and cost effective surface treatment method based on the use of commercial sodium bicarbonate (i.e. baking soda) on properties of sisal fibre and its epoxy composites. In particular, raw sisal fibres were treated with a 10%w/w of sodium bicarbonate solution for different periods (24, 120 and 240 h), at room temperature. Changes occurring in sisal fibres were characterized through scanning electron microscope, Fourier transform infrared spectroscopy, thermogravimetric analysis and helium pycnometer analysis.The mechanical characterization of sisal fibre was carried out through single fibre tensile tests and a reliability analysis of the experimental data was performed. A mathematical model was also applied to investigate the relation between the transverse dimension of the fibres and their tensile properties. Interfacial adhesion of sisal fibre with an epoxy matrix was investigated using single fibre pull out technique. Moreover, to deeper investigate the effect of the proposed treatment, epoxy based composites reinforced with short randomly oriented sisal fibres were manufactured and characterized by means of quasi-static flexural tests.The experimental results showed that 120 h is the optimum time for treating sisal fibre to achieve highest interfacial adhesion and mechanical properties with epoxy matrix.