Studies on Mechanical and Morphological Characterization of Developed Jute/Hemp/Flax Reinforced Hybrid Composites for Structural Applications

In the present study, an attempt has been made to develop and characterize natural fiber-based composites (jute/epoxy, hemp/epoxy, flax/epoxy) and their hybrid composites (jute/hemp/epoxy, hemp/flax/epoxy, and jute/hemp/flax/epoxy) using hand-lay-up technique. Mechanical characterization (tensile, flexural, impact, and hardness test) of the developed composites was performed. The interface between fiber and matrix was examined using scan electron microscopy (SEM). Among (jute/epoxy, hemp/epoxy, flax/epoxy), flax/epoxy composite has shown higher hardness (98 Shore-D) and tensile strength (46.2 MPa) whereas better flexural and impact strength have been shown by hemp/epoxy (85.59 MPa) and jute/epoxy (7.68 kJ/m²) composites respectively. Results showed that hybrid composites observed better mechanical properties. Jute/hemp/flax/epoxy hybrid composite showed the highest tensile strength, modulus and impact strength of 58.59 MPa, 1.88 GPa, and 10.19, kJ/m², respectively. Jute/hemp/epoxy hybrid composite achieved the maximum flexural strength of 86.6 MPa.     

An Experimental and Numerical Investigation on the Mechanical Properties of Addition of Wood Flour Fillers in Red Banana Peduncle Fiber Reinforced Polyester Composites

ABSTRACT

In this work, eco-friendly red banana peduncle fiber reinforced polymer composites (RBPF) and wood flour are added as a filler (RBWF) were prepared using compression molding process. These composites were analyzed by testing of properties such as tensile strength, flexural strength, impact strength, and water absorption. Tensile and flexural properties of the composites are verified using ANSYS. The chemical functional group of the composites was analyzed by Fourier transform-infrared spectroscopy (FT-IR). Microscopic examinations were conducted using the scanning electron microscopy (SEM) analysis. Crystallinity index (CI) and Crystalline Size (CS) of the composites were found by conducting X-ray diffraction (XRD) analysis. Results indicated their appropriateness in lightweight applications in automobile, construction and aviation industries.     

Analysis of flexural strength of preoxidized fiber-reinforced composites made by a nonwoven process and hot-pressing

Preoxidized fiber was used here as a reinforcement for the first time. Polypropylene fiber was used as resin matrix, and the preform with the two types of fiber was prepared by a nonwoven process. Then, hot-pressing was applied to make a treatment for the preform, and the thermoplastic composites reinforced with preoxidized fiber were prepared. The effects of the hot-pressing temperature, hot-pressing pressure, weight percentage of preoxidized fiber, and nonwoven process on bending failure strength along the machine direction (MD) and transverse direction (CD) were studied under a three-point bending load. It was concluded that the flexural strength of the composites along MD and CD decreases with increasing hot-pressing temperature and hot-pressing pressure, while an initial increase and then decrease was observed with the increase in the weight percentage of preoxidized fiber. However in both directions, flexural strength of the composites is influenced significantly by the nonwoven process. Finally, the bending failure mode of the composites generated micro-flaws, which can be observed on the center surface of the composites. The micro-flaws extend to the ends along the thickness direction of the composites, and plastic bending failure is observed due to partial delamination.     

Effect of silica nanoparticles on mechanical properties of Kevlar/epoxy hybrid composites

The addition of nanofillers in high-performance reinforcement results in the formation of hybrid composites. The objective of this research is to determine the effect of silica nanofillers loading on the mechanical properties of Kevlar/epoxy composites for ballistic use. Produced hybrid composite laminates were tested for flexural properties, tensile Properties and impact energy absorption. DMA analyses were performed to investigate composite properties at elevated temperatures. It was observed that introduction of silica nanofillers enhanced flexural properties, tensile strength, and storage modulus of composites. Impact energy absorption was increased up to a specific extent of nanofiller addition. The findings of this study indicate that introduction of silica nanofillers on Kevlar fabrics is a promising method for enhancing mechanical properties of hybrid composite laminates.     

Effect of Chemical Treatment on Thermal,Mechanical and Degradation Behavior of Banana Fiber Reinforced Polymer Composites

ABSTRACT

The current research endeavor, explores the thermal, mechanical, and degradation behavior of alkaline treated banana fibers reinforced polypropylene composites. Composites incorporating BF (20% w: w) treated with NaOH (5% w: v) aqueous solution were developed using extrusion-injection molding processes. After chemical treatment, the tensile, flexural and impact strength of the composite increases by 3.8%, 5.17%, and 11.50%, respectively. Scanning electron microscope (SEM) observations of tested specimens confirm the fiber pull out and fiber fracture as the main reasons for failure of developed composites under tensile and impact loading. The specimens were exposed to two different environments, water immersion and soil burial for 5 weeks for the degradation studies. The degradation behavior of composites was measured in terms of variation in weight and mechanical properties (tensile, flexural, and impact). The maximum degradation in mechanical properties was observed for the composites buried under soil. The composite lost 7.69%, 12.06%, and 3.27% of tensile, flexural, and impact strength, respectively.     

Effect of chopped/continuous fiber,coupling agent and fiber ratio on the mechanical properties of injection-molded jute/polypropylene composites

This paper presents the development of jute/polypropylene (PP) composites by twin-screw extrusion and injection molding. Jute/PP was compounded using twin-screw extruder and injection molded. The effects of chopped/continuous fibers, coupling agent and fiber ratio on mechanical properties were investigated. Tensile and flexural moduli of continuous jute/PP were greater than those of chopped fiber/PP. Tensile, flexural and impact strengths were greater in chopped fiber/PP along with elongation at break. Coupling agent improved the tensile and flexural strengths, and these increased with fiber content, whereas impact strength and elongation at break decreased with fiber loading. The results were analyzed using ANOVA and regression analyses.     

Cissus Populnea Fiber - Unsaturated Polyester Composites: Mechanical Properties and Interfacial Adhesion

ABSTRACT

Mechanical (flexural, hardness, and impact) properties and interfacial adhesion of acetic anhydride (AC) and ethylene diamine tetraacetic acid (EDTA) treated Cissus populnea fiber-unsaturated polyester (UPR) composites was investigated because of poor durability of the natural fiber-UPR composite applications. UPR composites were prepared with untreated and optimally treated fiber using hand-lay-up technique. Optimization of mechanical properties and interfacial adhesion between the fiber and UPR were determined using response surface methodology and fiber pull-out method, respectively. AC and EDTA treated fibers improved the flexural and hardness properties and interfacial adhesion at reduced impact strength. This is corroborated with morphology of the composites.     

A new assessment on mechanical properties of jute fiber mat with egg shell powder/nanoclay-reinforced polyester matrix composites

ABSTRACT

Natural fiber polymer matrix composites occupy the major percentage in applications due to its ecofriendly and low-cost nature. This study investigates the mechanical properties of a polyester matrix nanocomposite reinforced by the NaOH-treated jute fabric mat (NJM) and untreated jute fabric mat (UJM). In addition, the effects of egg shell powder (ESP) and nanoclay (NC) to the above has also been studied. The matrices were prepared with different combinations of presence and absence of the ESP, NC, and both as well as different weight percentage using compression molding process. The mechanical and morphological properties of the composites were determined. The tensile strength, flexural strength, and impact strength of NJM with NC 1.5%wt and ESP 1.5%wt were found to be 29.28 MPa, 39.51 MPa and impact strength 3.03 J, respectively. This composition is superior to the other compositions. Morphological analysis of tensile fractured surface showed interfacial adhesion between UJM and NJM composites. NJM composites contained smaller amount of pullouts and the splits compared with the UJM composites, which hold up the better performance.     

Development of electrically conductive composites based on recycled resources

Abstract

The current study was focused on the development of electrically conductive composites of carbon particle filled cotton fabric/epoxy systems. The carbon particles were refined to the scale of micro/nanoparticles using ball milling and morphological properties were studied by Malvern zetasizer and SEM. The influence of different concentrations of carbon particles in green epoxy resin for electrical conductivity was studied. Additionally, the electrical conductivity and electromagnetic shielding ability of conductive composites were analyzed. Waveguide method at high frequency (i.e. at 2.45?GHz) was used to investigate the EMI shielding. Similarly, the effect of different concentrations of carbon particles in composites was also studied for mechanical strength (tensile and flexural). A comprehensive study showed the improvements in electrical and mechanical properties with increase in the concentration of carbon particles and their even distribution in resin. The composites with higher carbon filler concentration showed maximum electrical conductivity (1.0E–02), shielding effectiveness 23.13?dB and mechanical properties.     

Effect of Green Gram Husk Nanocellulose on Banana Fiber Composite

Nanocellulose is a significant bio entity in the present-day applications of nanocomposites. In this regard, the present work focuses on fabrication of green gram husk cellulose-based hybrid nanocomposites. In the process of nanocellulose extraction, residues obtained after each stage of treatment are characterized through physical and morphological tests. Later, nanocellulose is reinforced in unsaturated polyester with 1, 3, 5, and 7 wt. % to study the tensile properties. The peak tensile strength is found to be 39 MPa at 5wt% of cellulose nanocomposites. Noting the enhancement in tensile properties of nanocomposites, nanocellulose is reinforced in banana fiber composites and its influence on mechanical properties is studied. Nanocellulose/banana fiber hybrid composites showed enhanced tensile strength, flexural strength, and impact strength.     

Effect of alkali treatment on mechanical properties of woven jute composites

The effect of alkali treatment on the jute fabrics and its influence on jute composites properties has been studied. The plain woven jute fabrics were manufactured using handloom. The alkali treatment was optimized using Box and Benkhen experimental design using time, temperature and concentration as independent variables and water absorbency, weight loss percentage as dependent variables. The fabric treated with optimized condition of 5% NaOH for 4 h at 30 °C was made into a composite of [0°]₄ lay-up sequence by means of compression moulding technique using vinyl ester resin. The composites were characterized for various mechanical properties such as tensile, flexural and impact strength. It is observed from the results that the alkali-treated samples show increased mechanical properties of the composites which may be due to the better adhesion between the fabric and the resin because of the removal of lignin and hemicellulose.     

Mechanical Characterization and Water Ageing Behavior Studies of Grewia Serrulata Bast Fiber Reinforced Thermoset Composites

Natural fiber-reinforced polyester composites were prepared using bast fibers as the reinforcement which were extracted from Grewia serrulata trees. Chemical treatments such as alkali pretreatment followed by permanganate treatment, acetylation and silane treatment were exclusively applied to modify the fiber surface. Hand lay-up technique with compression molding was adapted for the fabrication of axially oriented fiber reinforced composites. Tensile, flexural and impact strength properties of the specimens prepared were evaluated following the standard procedures. The SEM images of the fractured surfaces shows improvement in compatibility between the chemically treated fibers and the matrix. It was found that the tensile and flexural strengths of chemically treated fiber-reinforced polyester composites have significantly improved when compared to untreated fiber-reinforced polyester specimens. The properties of 1200 hrs water aged specimens were found deteriorated considerably due to diffusion of water into the composite material system. The chemical treatment of fibers prior to fabrication of composites improves the resistance to water absorption tendencies.     

Evaluation of physico-mechanical characteristics of cashew nut shell liquid-epoxy composites with Borassus and Tamarind fruit fibres as reinforcements

In this study, Cashew Nut Shell Liquid (CNSL)-epoxy matrix-based composites reinforced with borassus and tamarind fibres were fabricated using compression moulding technique. Three different types of composites were fabricated, namely Borassus fruit fine fibre/CNSL-epoxy composites (BF composites), Tamarind fibre/CNSL-epoxy composites (TF composites) and Tamarind/Borassus fruit fine fibre CNSL-epoxy hybrid composites (HB composites). In addition, CNSL-epoxy neat polymer was also fabricated for comparison. Physical properties such as micro-hardness, void percentage, and mechanical properties like tensile, flexural, Interlaminar Shear Strength (ILSS), and impact strength were investigated. Scanning Electron Microscope (SEM) was used to study the failure mechanism of the composites. Experimental results indicate that tensile and flexural properties of BF composites were higher when compared to TF and HB composites. Micro-hardness and impact strength of HB composites were better than the others. SEM images indicated better fibre-matrix bonding in BF composites indicating improved resistance to delamination. Thus, borassus and tamarind fibre reinforced CNSL-epoxy composites can be used as an alternative material for light to moderately loaded structural engineering applications.     

Polyvinyl Chloride Reinforced with Areca Sheath Fiber Composites—An Experimental Study

ABSTRACT

This research work deals with fibrous composites obtained by using treated and untreated areca sheath (AS) fibers reinforced in polyvinyl chloride (PVC) by injection molding process. Surface treatments of fibers have been carried out to have a better compatibility with PVC matrix. The tensile and flexural strength have been found to increase at the early stage with the increase in treated areca fiber content till optimum (18 wt% of fiber) fiber loading thereafter declines. At optimum fiber loading, the tensile strength, flexural strength and young’s modulus values are 42.38 MPa, 18.22 MPa and 2.38 GPa, respectively, which give maximum values in comparison to other fiber loadings. Thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), biodegradability tests and scanning electron microscopy (SEM) have been used for analysis. The TGA inferred that the thermal stability of the composites increased as compared to neat PVC matrix. Further, the composites exhibit excellent biodegradability property and their biodegradability increases with the increase of areca fiber content. From the properties obtained at optimum fiber loading (18 wt% of fiber), the composite can be suitable for automotive dashboard and door panel applications.     

Influence of modified carbonate calcium nanoparticles on the mechanical properties of carbon fiber/epoxy composites

Abstract

Multiscale composites have been investigated by the addition of silanized carbonate calcium (CaCO₃) as a secondary reinforcement into the matrix of carbon fiber/epoxy composites. The chemical modification of the CaCO₃ nanoparticles was confirmed by Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). Mechanical properties of the specimens were investigated by means of tensile, flexural, and compressive measurements to study the effect of treated CaCO₃ loading (0.5, 1, 3 and 5?wt.%) on their mechanical behavior. Experimental results showed that the tensile, flexural and compressive strengths of the specimen filled with 3?wt.% treated CaCO₃ composite enhanced by 14%, 36%, and 30% respectively, compared with those of neat one. The highest improvements in the mechanical moduli were observed in the multiscale composite filled with 5?wt.% treated CaCO₃. Also, the fracture surface of the specimens was further analyzed in detail.     

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

ABSTRACT

Usage 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.     

Interdependence of moisture,mechanical properties,and hydrophobic treatment of jute fibre-reinforced composite materials

Despite cheap and sustainable in nature, the use of natural fiber composites is limited due to their high moisture absorption, poor fiber–matrix interface, and lack of data on evolution of properties when subjected to environmental factor such as temperature and humidity. The aim of this research is to study the interdependence of moisture regain, hydrophobic treatment, and the mechanical properties of jute fiber-reinforced composite materials. Composite samples made from treated and untreated jute fiber-reinforced composites were exposed to humid environment and their moisture regain, mechanical properties and fiber-matrix interface was tested at given time intervals until four weeks. The composites produced with hydrophobic treated reinforcement showed lesser moisture regain and improvement in the tensile and flexural strengths compared to untreated fabric composite. A clear improvement in fiber-resin interface was observed by scanning electronic microscopy. The dynamic mechanical analysis of treated and untreated composites was conducted in a temperature range 20–140 °C. An increase in the storage modulus of treated composite materials was noted as compared to untreated ones. Furthermore, it was concluded that developed composite loss their mechanical properties linearly with immersion time. However, this aging was slow in treated fabric composites especially hybrid fluorocarbon and fluorocarbon.     

The effect of hydrophilic (polyvinyl alcohol) fiber content on the flexural behavior of engineered cementitious composites (ECC)

This paper investigates the effect of hydrophilic polyvinyl alcohol (PVA) fiber’s content (1.2–2.0% volume of composite) on the flexural behavior of engineered cementitious composites (ECC) materials. Different parameters of flexural behavior such as strength at first-cracking and post-cracking stages, deflection at ultimate load, toughness indices according to ASTM 1018, flexural modulus, and energy absorption were determined. Test results showed that the flexural strength and flexural modulus of composites significantly increases by increment in fiber content. However, flexural strength of composites varies from 8.5 to 14 MPa depending on amount of PVA fibers. The toughness indices, deflection at max load and energy absorption were decreased by further increase in the fiber content from 1.6 to 2%. It was indicated that there was an indirect relationship between flexural strength and ductility of composite in higher amount of fiber content.     

Mechanical properties and microstructure of 3D sinking woven quartz fiber-reinforced silica composites by silicasol-infiltration-sintering

Three-dimensional (3D) sinking woven quartz fiber-reinforced silica composites were successfully prepared by silicasol-infiltration-sintering process at a low temperature of 450°C. The density of the composites was 1.74?g/cm³. The characteristics of 3D sinking woven structure were determined. Flexural strength and shear strength of the composites were investigated along the warp and weft directions. Both flexural stress–displacement curves in warp and weft directions had two fractural points, e.g. matrix fracture point and fiber fracture point. The shear stress–displacement curves exhibited mostly nonlinear behavior. The composite in warp and weft direction reflects different shear behavior. Microstructural observations revealed that the adhesion strength between the fibers and the matrix was weak. There was a good state without serious degradation of quartz fibers during the preparation. Apart from these, the composites exhibited an extensive and long fiber pullout in the fracture surface. Crack deflection and fiber pullout contributed to the good toughness of the composites under the loading.     

Mechanical Response of Novel 3D Woven Flax Composites with Variation in Z Yarn Binding

ABSTRACT

This paper is focused on the development of novel 3D woven flax composites for improved mechanical performance. The 3D woven interlock fabrics were produced on dobby loom using novel weaving patterns, with variation in binding point density (four different levels). These fabric structures were then used to fabricate composites with green epoxy resin as a matrix. Tensile, flexural, short beam shear, impact (pendulum and drop weight) and compression after impact properties were characterized. It was found that 3D woven composites having higher binding point density showed overall improved mechanical behavior, i.e. the out-of-plane properties were enhanced whereas in-plane properties are either reduced or unaffected.