Untreated Fiber Composites Research Articles

Electrochemical construction of amino-functionalized GO/carbon fiber multiscale structure to improve the interfacial properties of epoxy composites

In this paper, two kinds of amino compounds with different functionalities were used to modify the surface of graphene oxide (GO), uniform and stable aqueous dispersion was prepared by adjusting the pH value. For the first time, two kinds of modified GO multi-scale reinforced structures with different morphology were successfully constructed on the carbon fiber (CF) surface by electrophoretic deposition. The analysis showed that the morphology of ethylenediamine modified GO on the surface of CF presented a “Post-it” structure, while the morphology of melamine modified GO was a “Bark” structure. The presence of the modified GO can significantly improve the specific surface area and infiltration of the fibers. Compared with untreated carbon fiber composites, the comprehensive mechanical properties of the modified composites increased by 30.8% and 40.9% respectively. The improvement of dynamic mechanical properties also means the formation of good interface layer. This research provides a novel idea for producing multi-scale reinforced materials on the fiber surface.

Elaboration and Study of the Properties of a Polyester Composite Made of Oleaster Fibers Treated and Untreated

ABSTRACT In this study, we have harvested natural oleaster (wild olive) fibers, processed and characterized in terms of physicochemical performance as well as mechanical properties. The main constituents of oleaster fibers with their weight proportions are cellulose (38.11%), lignin (19.4%), and ash (3.1%). The specific density of the oleaster fiber is measured to (1.40256 g cm−3). The average elastic modulus, tensile strength, and elongation at the break of composites made from polymer resin and oleaster fibers (untreated and treated with 20% acetic anhydride) have undergone an improvement in mechanical properties, respectively, an elastic modulus of 8.39 MPa for a deformation of 0.48334% against for the treated composite with the deformation of 3.95%for an elastic modulus of 55.53 MPa. Their Young moduli are 41.029 GPa for the untreated fiber composite and 93.19 GPa for the acetic anhydride treated fiber composite, respectively. We have also studied the effects of acetic anhydride treatment on the mechanical properties and structure of the fibers. When treated with 20% acetic anhydride for 2 h, the tensile strength of oleaster fibers had increased significantly. A longer treatment time did not show any appreciable improvement. However, the tensile strength remained higher than the tensile strength for untreated fibers.

The Effect of Alkali Treatment to Mechanical Properties of Resin Composite Reinforced with Coir Coconut Fiber

Previous research related to the effect of alkali treatment on mechanical properties of composite materials which generate the regression model is still rare. From the previous research, alkali treatment does not always improve the mechanical properties of composite materials. Therefore, it is necessary to research to make sure the effect of alkali treatment on coconut fiber composite. This study aims to examine the effect of alkali treatment of fiber combined with fiber weight content on the mechanical and physical properties of epoxy resin matrix composite. Mechanical properties testing is done by impact test and torsion test. The fracture surface was observed using optical microscopy. Data from the test results were analyzed to see the effect of alkali treatment on the mechanical properties of the resulting composite material by generating the regression model of impact strength and shear strength for treated and untreated fiber composites. The coefficient of determination (R2) of all models was 1. This study obtained that the untreated fibers have better impact strength and shear strength than the treated ones. The highest impact strength, 7.07 kJ.m2, and the highest shear strength, 1.81 MPa were obtained from the samples containing 4% untreated fibers.

The Effect of Fumigation and Alkalization on Dimensional Changes of Cantula Fiber Reinforced Unsaturated Polyester Composites Under Immersion

This study aims to investigate effect of fumigation and alkaline treatment on dimensional change in cantula fibers reinforced UPRs composite under immersion test in aqueous environment. Composites were fabricated using compression moulding method with cantula fiber content of 30% vt with the addition of 5% microcrystalline cellulose. Composite specimens were immersed under aquades for 2 months at room temperature. The dimensional changes of cantula fiber reinforced UPRs in different solutions were found to follow a Fickian behavior. Fumigation treated fibers and alkali treated fiber composites after immersion has lower results both in dimensional changes and its slope than untreated fiber composites.

Influence of Chemical Modification on Structural, Morphological, Thermal, and Weathering Behavior of Eulaliopsis Binata Fiber and Its Composites

ABSTRACT In the present investigation, the influence of chemical treatment on the structural, morphological, thermal, and weathering behavior Eulaliopsis Binata (EB) fiber was studied. Composites were fabricated containing both untreated and chemically treated (with acetone, alkali, and benzoyl chloride) EB fibers. The mechanical characterization of the developed composites was carried out for both treated and untreated EB fiber composites to assess the effect of chemical modification on the mechanical properties. The maximum tensile and flexural strength were observed for benzoylated fiber composites. The percentage increase in the tensile and flexural strength of 30 weight fraction EB fiber composites was found to be 43.2% and 47.05% with respect to untreated fiber composites. The fractured surfaces of the specimens were studied using a Scanning Electron Microscope (SEM) to explore the fracture mechanisms of the developed composites.

Investigation of Mechanical Properties of Sansevieria cylindrica Fiber/Polyester Composites

Natural fiber-reinforced composites are the most cost-effective and environmentally friendly alternative to industrial applications. Composite materials reinforced with Sansevieria cylindrica (SC) fibers were developed in this research work. These fibers were chosen for their outstanding mechanical qualities. Compression moulding was used to create composite materials. Each leaf on a Sansevieria cylindrica plant is 20 to 30 mm thick, with a height of 1000 to 2000 mm. The Sansevieria cylindrica (SC) fibers were used as chemically treated fibers and untreated fibers to produce the composites. The tensile strength, hardness, and impact strength of various fiber weight% of composites (20%, 30%, 40%, and 50%) were calculated. From the tested results, the maximum tensile strength achieved in 40 wt% of treated SC fiber composites is 85.7 MPa. The maximum hardness is found in 40 wt% of composites in both treated and untreated fiber composites. The 40 wt% of composites gives a better impact energy of 9.4 J/cm2.The SC fiber polyester composites have superior interfacial bonding and give maximal strength in treated SC fiber composites. The fiber treatment delivers greater strength than the untreated fiber, according to this study. The treated SC fibers have better strength and good bonding between the fiber and matrix to produce the composite materials.

Facile and eco-friendly functionalization of basalt fiber with polyelectrolyte complex toward excellent interfacial adhesion of epoxy composites

In an attempt to increase the interfacial adhesion of basalt fiber/epoxy composites, a surface modification strategy by constructing ternary polyelectrolyte complex consisted of silane coupling agent-phytic acid-polyethyleneimine via dip-coating is proposed for the first time in the present work. The as-prepared functionalized basalt fiber composite exhibits markedly improved interfacial shear strength, with an average value of 81.9 ± 4.5 MPa, 75% augmentation over that of untreated basalt fiber composite. The reinforcing mechanisms are attributed to the multiple interactions of ionic cross-linked network, covalent and hydrogen bonding at interphase, also including the improved wettability and relatively rough fiber surface. Together with facile preparation approach, nature and low-cost material, the ternary polyelectrolyte complex system developed in this paper offers great potential in practical functionalization of basalt fiber, which could be hopefully extended to other high-performance fibers.

A Review on the Effect of Various Chemical Treatments on the Mechanical Properties of Renewable Fiber-Reinforced Composites

Increased environmental concerns and global warming have diverted effort all over the world to focus on renewable and sustainable resources for the next generation of composite products due to their recyclability, renewability, cost effectiveness, and satisfactory mechanical performance. Bio/natural fibers which are environment friendly materials employed as reinforcement have led to developing a biocomposite for reduction in greenhouse emission and carbon footprints. However, biofibers are also having some limitations that need to be addressed including poor compatibility between the reinforcing fiber matrices, high moisture absorption, swelling, poor chemical and fire resistance, and high dispersion of mechanical properties. A lot of research has been performed on physical and mechanical properties of natural fiber composite. Properties of such novel composite mainly depend on adhesion between fiber and matrices. Consequently, poor adhesion, high moisture absorption, and swelling lead to formation of crack in both the matrix and fiber. Therefore, numerous techniques have been tried till date to modify both fiber surfaces to enhance their adhesion and reduce their water absorption. This review article provides comprehensive information about effect of various surface modification techniques that include alkaline, silane, acetylation, permanganate, peroxide, benzoylation, acrylonitrile grafting, maleic anhydride grafted, acrylation, and isocyanate. In addition, the effects of cellulose, hemicellulose, lignin, and pectin of biofibers are also reported. This review concluded that chemical treatment of biofibers with 5% NaOH concentration improves the physical, mechanical, and thermal properties of the resulting composites compared to untreated fiber composites.

Investigation of Weight Fraction and Alkaline Treatment on Catechu Linnaeus/Hibiscus cannabinus/Sansevieria Ehrenbergii Plant Fibers-Reinforced Epoxy Hybrid Composites

The aim of the present work is to develop novel hybrid composites using areca, kenaf, and snake grass fibers as reinforcement and epoxy as the matrix. The areca, kenaf, and snake grass fibers were extracted from Catechu Linnaeus, Hibiscus cannabinus, and Sansevieria Ehrenbergii plants, respectively, and treated with 5% NaOH to improve the interfacial adhesion between the hydrophilic fiber and the hydrophobic matrix. Hybrid composites were developed by the compression molding technique and formulated based on the weight fraction of fibers. Tensile, flexural, and impact strength and hardness samples were prepared as per ASTM D 3039, ASTM D 790, ASTM D 256, and ASTM D 2240, respectively. The effects of alkaline treatment on developed hybrid composites were investigated. The developed hybrid composites with 20% wt. snake grass and 10% wt. areca fiber present interesting mechanical properties with a tensile strength of 58 MPa, flexural strength of 124 MPa, impact strength of 5.24 kJ/m2, and hardness of 88. The results indicate that maximum mechanical properties were obtained for alkaline-treated fiber composites with 20% wt. snake grass fiber compared to untreated fiber composites owing to better adhesion between the treated fiber and the matrix. The effect of alkaline treatment was analyzed by Fourier transform infrared. The fractured surfaces of tested samples were analyzed by scanning electron microscopy.

Mechanical, Morphological, Thermal and Dynamic Study of Composites of Unsaturated Polyesters-Date Palm Leaf Fiber DPLF

In order to improve the properties of unsaturated polyesters, this study discusses the possibilities of developing a natural waste, date palm leaf fiber DPLF, produced in the northern Algerian Sahara, associated with the polymer matrix of a thermosetting polyester resin UP. For this purpose, composite plates containing virgin fiber at rates of 6 and 10% were treated with an alkaline solution of 6% NaOH on the one hand, and a silane compound on the other. In this research, a mechanical study of strength and elongation at break was carried out. In addition, morphological behavior was followed by SEM scanning electron microscopy. ATG thermogravimetric analysis and energy flow were monitored by DSC differential scanning calorimetry. Also, a study of the water absorption capacity has been conducted. In addition, a dynamic mechanical analysis DMA was carried out. The findings of this study show that there is a favorable mechanical behavior for the composites containing the 6% and 10% DPLF fiber, with alkaline NaOH and Silane treatment. They also show that the chemical treatment with alkaline solution and silane gives composites certain thermal stability compared to those with untreated fiber. Findings also explore that the absorption of water by the various composites shows that the chemical treatment promotes some intermolecular associations with water. Findings also show that the storage modulus (E') increases when the composite contains 10% DPLF, treated and untreated, and the maximum value of the tangent moves towards the high temperature for the treated and untreated fiber composite.

FRESH STATE AND MECHANICAL PROPERTIES OF ULTRA-LIGHTWEIGHT FOAMED CONCRETE INCORPORATING ALKALI TREATED BANANA FIBRE

For a Lightweight Foamed Concrete (LFC) to efficiently function as an energy-saving building material, its self-weight (density) should be reduced. However, the problem associated with a reduced density is a decline in strength. To improve the mechanical properties of LFC, this research attempts to integrate banana fibre into LFC composite with a focus on fresh and harden state properties. An Ultra-Lightweight Foamed Concrete (ULFC) with a density of 600 kg/m3 was produced with the inclusion of treated and untreated banana fibres. The volume fractions of banana fibre added into LFC were 0.00% (control specimen), 0.25%, 0.35%, 0.45% and 0.55%. In addition, an optimised batch mix of ULFC reinforced with 0.35% untreated banana fibre was produced. The batches were tested for rheological, physical, and mechanical properties. Findings reveal that the workability of ULFC composites decrease with increase in fibre addition. The compressive, flexural, and tensile strengths of the alkali-treated composites were higher than the untreated banana fibre composite. SEM micrograph reveals that defibrillation of bundle fibrils due to cleaning the surface amorphous hemicellulose, lignin and pectin of the alkali-treated fibre, leads to rough surfaces and increase surface area resulting in better interfacial adhesion of the fibre with cement matrix.

Influence of sodium bicarbonate treatment on the free vibration characteristics of Phoenix sp. fiber loaded polyester composites

Natural fiber-based polymeric composites have become increasingly popular in machine tool and automobile applications in recent years. While, using the composite in such applications, it may fail due to excessive vibrations caused by dynamic loads. Therefore, it is necessary to understand the free vibration behavior of composites before employing it to such applications. The purpose of this work is to compare the free vibration characteristics of untreated and sodium bicarbonate treated Phoenix sp. fiber reinforced polyester composites fabricated through compression molding technique with different fiber content (0, 10, 20, 30 and 40 wt.%) and constant fiber length (20 mm). The chemical treatment was carried out for different time periods (24, 120 and 240 h) with 10 wt.% concentration of sodium bicarbonate solution. The results revealed that the natural frequency of treated fiber composites was greater than the untreated fiber composites which maybe ascribed to the increased stiffness of the fibers and interfacial bonding after the treatment. In addition to this single fiber pull-out test was also performed to assess the interfacial strength among the composite constituents. Especially, the composites loaded with 120 h treated fiber showed better results and it can be suggested for various engineering applications.

Effect of surface treatment on tensile and buckling characteristics of natural fibre based hybrid composites

Natural fiber reinforced polymer composites have raised their potential in different fields due to their high strength to weight ratio, abundantly available in nature and bio-degradable characteristics. The aim of present study is to familiarize the mechanical characteristics such as tensile properties and buckling strength of treated and untreated bamboo/nettle fiber reinforced epoxy hybrid composites. Also volume fraction of fiber and matrix was kept at 70%-30% in which 40% of nettle and 30% of bamboo fibers were used in this investigation. Bamboo and nettle fabrics were cut and immersed in 10% NaOH (sodium hydroxide) solution for 6 hrs to improve their surface morphology. Samples of several bamboo-nettle based natural hybrids were fabricated using vacuum bag technique where the layers of fabrics are placed alternately. Specimens are cut from the fabricated hybrid laminates for tensile test and buckling test as per ASTM standards. For tensile and buckling test samples were cut in the form of dog-bone shape and rectangular panels respectively. The tensile and buckling tests were performed using computerized UTM. The tensile and buckling values are computed for treated and untreated fiber composite to perceive the change in length. Result shows that alkali treated fiber composite has better tensile and buckling properties as compared to untreated fiber composites. This is due better interfacial bonding between fiber and matrix leads to increase of composite properties.

Development and characterization of epoxy resin composite reinforced with bamboo fiber and bagasse as filler

PurposeRecently, composites have concerned considerable importance as a potential operational material. Lots of work have been carried out to enhance the mechanical properties of composites. The main aim of this paper is to develop bamboo mat as reinforcing material with bagasse fiber as filler using epoxy resin matrix composite.Design/methodology/approachIn this research, the effect of fiber surface treatments on mechanical properties of epoxy resin composite with bagasse as filler has been developed and investigated. The extracted bamboo fibers were treated with NaOH to improve the surface roughness fiber. Using treated and untreated bamboo fiber handwoven mat has been produced to be used as reinforcement and bagasse fiber has been converted into powder to be filled as filler. Composite material is fabricated using bamboo fiber and bagasse fiber as filler with epoxy resin as a matrix using hand layup technique.FindingsThen, tensile, flexural and compressive strength and water absorption tests were conducted on sodium hydroxide treated and untreated fiber composites. The test results comparing with and without alkali treated composites show that there was significant change in their strength and water absorption properties on alkali treated fiber.Originality/valueThis study is an original research paper.

Improvement of Mechanical and Thermal Properties of Polyethylene Terephthalate (PET) Composite Reinforced with Chemically Treated Ladies Finger Natural Fiber

ABSTRACT In the present work, ladies finger (LF) fiber has been utilized as reinforcement in thermoplastic polymer, polyethylene terephthalate (PET). The extracted fibers were chemically treated, and the effect of chemical treatment of fibers on mechanical and thermal properties of composites was investigated and discussed. For this purpose, the fibers were treated with chemicals like sodium hydroxide at various concentrations (2%, 3%, 4%, and 5%). Then, the chemically treated fibers with varying weight percentage (0, 10, 20, 30, and 40 wt%) were reinforced in PET to develop new composites, and its various properties like mechanical properties, thermogravimetric analysis, Fourier transform infrared spectroscopy, and X-ray diffraction were thoroughly investigated and compared with untreated fiber composites and neat PET. It has been observed that the composites fabricated with treated LF fibers reveal improved properties as compared to composites containing untreated fibers. Moreover, a better fiber–matrix bonding is also observed in scanning electron microscopy images. Twentywt% of fiber loading reveals highest mechanical properties as compared to other fabricated composites and can be suitable for packaging applications.

Studies on physico-mechanical behaviour of kenaf/glass fiber reinforced epoxy hybrid composites

In this study, various treated, untreated, and treated kenaf/glass fiber composites were fabricated using epoxy resin. A portion of kenaf fibers were subjected to treatment with alkali, sub-portion was taken for benzoyl peroxide and potassium permanganate prior to composite fabrication. This treatment on the composite material was undertaken to achieve improved modification of the interface between the matrix and fiber bond. A portion of the glass fiber was used for enhancing the mechanical properties of the hybrid composite. The tensile strength, flexural, density, water absorption and chemical resistance of the composites were analyzed using standard methods. FTIR was conducted on the fiber to ascertain the chemical treatment on the fibers, FESEM was used for the morphological study. The results obtained showed that the tensile and flexural strength improved from 46.45-298.3 kgf, and 10.5-54.7 kgf, respectively, in the composite samples. Chemical resistance of the kenaf fiber treated potassium permanganate composite improved compared to the untreated fiber composite in both cases. The density and water absorption properties of the composites were found to decrease in the treated fibers compared to untreated fiber composites, this treated composites showed less water absorption and density. The FTIR result revealed that reaction has taken place between the fiber and the treatment reagent. Hence, fiber modification has improved the properties of the composites due to increase in fiber-matrix interaction.
 
 KEY WORDS: Chemical properties, Epoxy resin, Hybrid, Kenaf, Mechanical strength, Natural fiber
 
 Bull. Chem. Soc. Ethiop. 2021, 35(1), 171-184.
 DOI: https://dx.doi.org/10.4314/bcse.v35i1.15

Study of Mechanical Properties of Alkali Treated SZF/SF/VE Hybrid Composites under Wet Condition

Mechanical properties of vinyl ester hybrid composites reinforced with alkali treated Smilax zeylanica and sisal fibers were studied at wet condition in the present communication. Hybrid composites were fabricated by using a simple hand lay up technique based on three different fiber loading of 25, 35, and 45 wt.% with alkali treated fibers. Hybrid composite specimens were then subjected to the water absorption test to observe the behaviours of composite specimens at wet condition under mechanical loads such as tensile, flexural and impact. Water absorption test was carried out in two ways at distilled water environment at room temperature. First way test was conducted for 10 days to observe the percentage of water particle absorption of hybrid composites. Second way test was performed for 5 days to determine the mechanical properties of hybrid composites at wet condition to observe its durability when they are used in outdoor applications. Mechanical properties of hybrid composite specimens at wet conditions were compared with the dry composite specimens. Experimental results showed that the percentage of the water particle absorption in the alkali treated hybrid fiber composites is lower as compared to the untreated hybrid fiber composites. Mechanical properties of alkali treated hybrid fiber composites at wet condition are slightly reduced as compared to the treated hybrid fiber composite at dry condition. As a result, it is observed that the resistance for the penetration of the water particles is higher for the alkali treated smilax zeylanica and sisal fibers reinforced vinyl ester hybrid composites. The fracture surfaces of the hybrid composite specimens were examined by scanning electron microscope to understand the effects of water absorption on the mechanical properties.

Study on morphological and mechanical properties on treated and untreated veldt grape/PLA composites

Composite materials made up of natural fiber have gained more importance in automobile industries due to their lightweight, non-abrasive properties, fair cost, and environmental friendliness. The chemical treatment on the fiber surface enhances the individual fiber mechanical property which leads to the same benefits in the composite preparation too. In this study, an attempt was carried out to analyze the chemical treated composite over untreated composite. The reinforcement fiber veldt grape and matrix resin polylactic acid was chosen for composite preparation. By the two roll mill followed by compression molding technique the untreated and chemical treated composites were prepared. The mechanical properties tensile, flexural, impact, water absorption tests were performed on untreated and chemical-treated composites. The morphological analysis was performed on both untreated and chemical-treated fiber composites by scanning electron microscope. The chemical-treated composite is observed to have considerably increased favorable mechanical properties than the untreated fiber composite. The morphology of the chemical-treated fiber composite is seen to have superior interaction with the fiber matrix.

Optimization of mechanical properties of cellular lightweight concrete with alkali treated banana fiber

Recent advancements in construction materials development have involved the utilization of plant-based natural fibers such as kenaf, sisal, coir and banana to replace conventional fibers such as carbon, steel, polypropylene and aramid. However, the main issue with using these fibers is the alkaline cement matrix's durability and compatibility due to high water absorption. Hence, this research focuses on the use of alkali treatment of banana fibers to enhance the mechanical properties of cellular lightweight concrete (CLC). Banana fibers were subjected to 2%, 4%, 6%, 8%, and 10% NaOH treatment before being included in 1200 kg/m3 density CLC. Plain CLC and untreated fiber composites (0% NaOH treatment) were used as the control. Results from the study indicate that compared to the untreated fibre composites and plain control CLC at 28 days, compressive, flexural and splitting tensile strengths increased simultaneously with 6% NaOH fibre treatment to peaks of 40.6% and 59.8%, 63.8% and 117.4%, and 77.4% and 157.8% respectively. The 6% NaOH treatment of BF tremendously improved the mechanical characteristics of single fibers and BFRCLC composites. It is therefore concluded that 6% NaOH treatment of banana fibre was the optimum percentage alkali treatment for use in CLC.

Low Density Linear Polyethylene Reinforced with Alkali and MAPE Treated Fibers from Coffee Pulp

In this work fibers derived from coffee, hulls have been incorporated into Linear Low Density Polyethylene (LLDPE). The influence of the filler content on the thermal and physicomechanical properties of the composites obtained was assessed. The results showed that the incorporation of fibers was able to improve the thermostability of LLDPE/Coffee hulls fibers; comparing the treated fiber composite with untreated fiber composites, the chemical treatment reduces by 58.3% the water absorption, while increasing the elongation and tensile strength by about 48% and 17% respectively. Moreover, due to better interfacial interaction induced by MAPE, the corresponding composite exhibited better properties compared to the untreated fiber composite. Results are indicative of the fact that both mercerization and MAPE (coupling agent) have significant positive effects on the fiber-matrix interaction in terms of adhesion, wetting and dispersion, this treatment produced a better fiber distribution and consequently a more uniform composite morphology without voids and gaps between the fibers and the matrix, allowing the possibility to use higher fiber contents (up to 30% wt.) with acceptable mechanical properties.