Mechanical and Thermal Characterization of Natural Intralaminar Hybrid Composites Based on Sisal

A bibliometric review on applications of lignocellulosic fibers in polymeric and hybrid composites: Trends and perspectives

Over the past 10 years, materials science and engineering have shown increasing interest in incorporating lignocellulosic fibers into polymer and hybrid composites (LCF-CPH). This bibliometric analysis, covering the period 2012 to 2022, examines the current state of research on the application of these fibers in composites, with the aim of identifying significant contributions, new trends, and possible future directions. The analysis included a comprehensive database search using specific criteria, which revealed a significant increase in research activity on a variety of lignocellulosic fibers, such as flax, jute, hemp and sisal. This growth is particularly evident in the packaging, automotive, aerospace and construction industries. Hybrid composites based on these fibers have gained prominence due to their enhanced properties, which include improvements in mechanical, thermal and environmental characteristics. The findings of this research have significant implications for governments, corporations, and academic institutions. Researchers gain a deeper understanding of emerging trends, industry gains valuable insights into the advantages of adopting lignocellulosic fibers, and policymakers gain essential information to support the development of sustainable composites. In the field of advanced composites and sustainable materials, this work lays a solid foundation for future research and industrial applications.

Physical and thermomechanical characterization of unidirectional Helicteres isora fiber-reinforced polylactic acid bio-composites

Identifying novel cellulose fiber bio-composites has become a vital initiative in the exploration of sustainable materials due to increased global concern for the environment. This growing focus on eco-friendly materials has gathered significant attention in recent years. The current investigation deals with one such material, Helicteres isora reinforced Polylactic acid composites. Surface chemical treatment of fiber is one of the most effective methods to modify the hydrophilic fiber to increase its compatibility with the polymer matrix. Sodium hydroxide was used as a pre-treatment chemical to remove any impurities from the fiber surface. Pre-treated fibers were treated with Methacryl silane and Potassium permanganate solution to chemically modify the fiber surface. Density, void content and water absorption behavior of the composites were analyzed as per the standard procedure. Tensile and flexural tests were conducted to evaluate the mechanical strength, modulus, and flexibility of the unidirectional composites. Thermogravimetric and differential thermal analyses were performed to investigate the thermal stability, melting behavior and degradation profiles of prepared composites. A study of failure mechanisms and morphology of the fractured surface through photographs and SEM images revealed fiber splitting and delamination as the dominant reasons behind the failure of composites under tensile loading. Silane-treated Helicteres isora fiber-reinforced Polylactic acid composite exhibited lower water absorption and higher tensile strength than its counterparts. Untreated fiber composite showed maximum flexural strength among the tested composites. By collectively evaluating the results of the tests and properties of the composites, silane-treated fiber-reinforced Polylactic acid composites stands out as the most favorable choice.

Stress Concentration on PDMS: An evaluation of three numerical constitutive models using digital image correlation

The examination of hyperelastic materials' behavior, such as polydimethylsiloxane (PDMS), is crucial for applications in areas as biomedicine and electronics. However, the limitations of hyperelastic models for specific stress scenarios, with stress concentration, are not well explored on the literature. To address this, firstly, three constitutive models were evaluated (Neo-Hookean, Mooney-Rivlin, and Ogden) using numerical simulations and Digital Image Correlation (DIC) analysis during a uniaxial tensile test. The samples were made of PDMS with stress concentration geometries (center holes, shoulder fillets, and edge notches). Results of ANOVA analysis showed that any of the three models can be chosen for numerical analysis of PDMS since no significant differences in suitability were found. Finally, the Ogen model was chosen to obtain the stress concentration factors for these geometries, a property which characterize how discontinuities change the maximum stress supported by an element. Our study provides new values for variables needed to analyze and design hyperelastic elements and produce a foundation for understanding PDMS stress-strain behavior.

Physico-chemical and extraction properties on alkali-treated Acacia pennata fiber

The production of reinforced composite materials can generally benefit greatly from the use of natural cellulosic woody fibers as good sustainable resources. Natural plants like hemp, cotton, and bamboo are great options for knitters and crocheters looking to make eco-friendly goods. The current study examines the properties of natural fiber obtained from the stem of the Acacia pennata (AP) plant, as well as its basic physico-chemical, structural, thermal, and mechanical characteristics. The key goal of this work was to investigate how alkali treatment affected the AP fibers' morphology, chemical composition, tensile capabilities, morphological changes, structural changes, and thermal degradation (APFs). The SEM image and pXRD analyses support the improved surface roughness of the fiber, and that was seen after the alkaline treatment. From XRD analysis, the fiber crystallinity index (54.65%) was improved and it was connected to their SEM pictograms in comparison to untreated APF. Alkali-treated AP fibers include a higher percentage of chemical components including cellulose (51.38%) and ash (5.13%). Alkali-treated AP fibers have a lower amount of hemi-cellulose (30.30%), lignin (20.96%), pectin (8.77%), wax (0.12%), and moisture (13.44%) than untreated APF. Their low density and high cellulosic content will improve their ability to fiber matrices. The thermal behavior of AP fiber at various temperatures was demonstrated by TG-DTA analysis, and tensile strength was also investigated.

Natural Fibre Composites and Their Mechanical Behaviour

At present, natural-fibre-reinforced-composites (NFRCs) are seen as realistic alternatives to synthetic- (e [...].

Investigation of Hemp and Flax Fiber-Reinforced EcoPoxy Matrix Biocomposites: Morphological, Mechanical, and Hydrophilic Properties

Modern day industries are highly focused on the development of bio-inspired hybrid natural fiber composites for lightweight biosensor chips, automobile, and microfluidic applications. In the present research, the mechanical properties and morphological characteristics of alkaline (NaOH)-treated hemp, flax, noil hemp, and noil flax fiber-reinforced ecopoxy biocomposites were investigated. The samples were fabricated by employing the hand layup technique followed by the compression molding process. A total of two sets of composites with various weight fractions were fabricated. The samples were tested for mechanical properties such as flexural strength, interlaminar shear strength, moisture absorption, and contact angle measurement. The treated fibers were analyzed by using an optical microscope and Fourier transform infrared spectrometer (FTIR). The morphological characteristics, such as porosity and fracture mechanisms, were investigated by using scanning electron microscopy and SEM−EDX spectroscopy. The results revealed that the flexural properties of hybrid composites vary from 22.62 MPa to 30.04 MPa for hemp and flax fibers and 21.86 MPa to 24.70 MPa for noil fibers, whereas in individual fiber composites, the strength varies from 17.11 MPa to 21.54 MPa for hemp and flax fibers and 15.83 MPa to 18.79 MPa for noil fibers. A similar trend was observed in interlaminar shear properties in both cases. From moisture analysis, the rate of absorption is increased with time up to 144 h and remains constant in both cases. The moisture gain was observed more in individual composites than hybrid composites in both cases. Hence, the impact of hybridization was observed clearly in both cases. Also, hybrid composites showed improved properties compared to individual fiber composites.

Influence of Nanosilica Particle Addition on Mechanical and Water Retention Properties of Natural Flax- and Sisal-Based Hybrid Nanocomposites under NaOH Conditions

Organic filament-based lightweight materials are increasingly being used because of their high strength-to-weight ratio, recyclability, and low cost. The application of nanofillers in addition to natural fibres is a fascinating one. The main purpose of the current experimental investigation is to manufacture and estimate the mechanical material of nanocomposites. Natural fibres like flax and sisal are used as reinforcement; nanosilica particles act as fillers, and epoxy resin as a matrix. The composites were created using the Taguchi L9 orthogonal array and a hand lay-up technique. The mechanical and water retention behaviour of the hybrid composites is based on the following three parameters, each with three different levels: (i) adding different weight ratios of nanofiller (1.5, 3, and 4.5 wt%), (ii) weight ratio of reinforcements (20, 30, and 40 wt%), and (iii) duration of NaOCl conditions (2, 4, and 6 hours). Mechanical possessions like tension, bending, and impact were tested as per the ASTM standard. The tested composites show that 30 wt% reinforcement, 3 wt% nanosilica, and 4 hours of alkaline processing provide the best materials and aquatic preoccupation belongings. When compared to nanofiller composites, nanoparticle-filled composites have 17% evolution in tension, 22% upsurge in flexural strength, 13% in impact strength, and 36% increase in impact strength hygroscopic behaviour. Scanning electron microscopes were used to analyze the fractured structure of hybrid composites. Compared to 1.5 and 4.5 wt% of nanofiller, the 3 wt% of filler provides high interfacial adhesion to the hybrid composites. It helps the reinforcement and matrix to contact each other.

Water Retention Behaviour and Fracture Toughness of Coir/Pineapple Leaf Fibre with Addition of Al2O3 Hybrid Composites under Ambient Conditions

Due to their high mechanical and physical properties, natural fibre-based composite materials have been important in many fields of application for four to five years. The chief intention of the current study is to determine the mechanical and water retention features of composite materials under ambient conditions. Coir and pineapple leaf fibre were used as a reinforcement, aluminium oxide as additives, and polyester as a matrix. The hybrid resources were laminated by the manual hand lay-up method. The mechanical characteristics like tensile, flexural, and fracture toughness properties were tested as per the ASTM standard. Nanoparticle weight ratio and its size variation significantly impact mechanical qualities. The hybrid composite’s water retention behaviour was tested for two types of water levels: ordinary tab water and nanofluid. The moisture uptake of the composites rose as the fibre volume increased, and after 640 hours, all of the composites had reached equilibrium. According to the results, the following combinations have the maximum mechanical strength: 15% wt.% coir, 15% wt.% pineapple, 10% wt.% nanofiller, and 60% wt.% polyester resin. The combinations mentioned above withstand the most load during the tests. Compared to 20% filler, 10% Al2O3 filler produces good interfacial adhesion in the current study. The fractured specimens were analyzed using scanning electron microscopic (SEM) pictures to recognize better the failure process of composites during mechanical testing.

Effect of Nano TiO2 Filler Addition on Mechanical Properties of Bamboo/Polyester Hybrid Composites and Parameters Optimized Using Grey Taguchi Method

Exploration has shifted from traditional materials and alloys to composite materials in recent years to develop lightweight, high-effective materials for specific purposes. Natural fibres are less costly, biodegradable, and nonflammable than glass fibres. This study explores how titanium oxide affects woven polyester reinforced composite’s mechanical and physical characteristics. Nanocomposites were created by hand utilizing the following terms: (i) TiO2 nanoparticle filler weight ratio, (ii) fibre content, and (iii) fibre diameter, all at three unique levels. Using the L9 (33) orthogonal design, nine composite samples are generated and tested according to the ASTM standard. According to the research, hybrid composites containing 4% titanium oxide powder and 15 mm length of bamboo fibre with 0.24 mm of bamboo fibre diameter have high mechanical strength. Adding fibre to pristine polyester increased its mechanical properties. As the fibre and filler percentages grew, more effort was required to break the fragments between the matrix and its resin. The verification test, which uses the optimal processing value and grey relational analysis, outperforms the real test results by a wide margin. Tensile strength increased by 14.76%, flexural strength increased by 14.07%, and hardness increased by 25.55%.

Numerical and Experimental Analysis of Mechanical Properties of Natural-Fiber-Reinforced Hybrid Polymer Composites and the Effect on Matrix Material

The impact of matrix material on the mechanical properties of natural-fiber-reinforced hybrid composites was studied by comparing their experimental, and numerical analysis results. In the present work hemp and flax fibers were used as reinforcement and epoxy resin and ecopoxy resin along with hardener were used as matrix materials. To study the influence of the matrix material, two sets of hybrid composites were fabricated by varying the matrix material. The composite samples were fabricated by using the compression-molding technique followed by a hand layup process. A total of five different composites were fabricated by varying the weight fraction of fiber material in each set based on the rule of the hybridization process. After fabrication, the mechanical properties of the composite samples were tested and morphological studies were analyzed by using SEM-EDX analysis. The flexural-test fractured specimens were analyzed by using a scanning electron microscope (SEM). In addition, theoretical analysis of the elastic properties of hybrid composites was carried out by using the Halpin–Tsai approach. The results showed that the hybrid composites had superior properties to individual fiber composites. Overall, epoxy resin matrix composites exhibited superior properties to ecopoxy matrix composites.

Improvement of Mechanical, Thermal, and Physical Behaviors of Jute/Cotton Biocomposites Reinforced by Spent Tea Leaf Particles

Natural fibers such as jute, cotton, and bamboo composites are becoming alternative materials to synthetic fiber composites, as their use raises awareness of environmental protection. Among natural fibers, jute and cotton fibers were used in this research to fabricate six-layered composites reinforced by spent tea leaves. Varying amounts (0, 5, 10, and 15 g) of spent tea leaf powder were incorporated as reinforcement with resin to improve and observe properties and determine usability. The prepared composites were investigated comparatively in terms of mechanical, microstructural, morphological, and thermal properties. As regards mechanical characterization, tensile, compression, and bending properties were tested in this research to compare the obtained data with the data available in the literature to show its practical application. The results indicated that significant improvements in mechanical properties were obtained from the composites up to a certain proportion of reinforcement. The addition of 10 g reinforcement of spent tea leaves improved tensile strength by 33.46% and compressive strength by 38.86%. In terms of microstructural, morphological, and thermal characterization, in-depth SEM, EDS, XRD, UV, FTIR, TGA, and DSC analyses were performed. The results revealed that advanced microstructural, morphological, and thermal properties were improved with a certain proportion of spent tea leaf reinforcement.

A Review on the Effect of Fabric Reinforcement on Strength Enhancement of Natural Fiber Composites

The main objective of this study is to examine the impact of reinforcements on the strength of natural fiber composites. Recent advancements in natural fiber composites have minimized the usage of man-made fibers, especially in the field of structural applications such as aircraft stiffeners and rotor blades. However, large variations in the strength and modulus of natural fiber degrade the properties of the composites and lower the safety level of the structures under dynamic load. Without compromising the safety of the composite structure, it is significant to enrich the strength and modulus of natural fiber reinforcement for real-time applications. The strength and durability of natural fiber can be enriched by reinforcing natural fiber. The reinforcement effect on natural fiber in their woven, braided, and knit forms enhances their structural properties. It improves the properties of natural fiber composites related to reinforcement with short and random-orientation fibers. The article also reviews the effect of the hybridization of natural fiber with cellulosic fiber, synthetic fiber, and intra-ply hybridization on its mechanical properties, dynamic mechanical properties, and free vibration characteristics, which are important for predicting the life and performance of natural fiber composites for weight-sensitive applications under dynamic load.

A Review on the Thermal Characterisation of Natural and Hybrid Fiber Composites

The thermal stability of natural fiber composites is a relevant aspect to be considered since the processing temperature plays a critical role in the manufacturing process of composites. At higher temperatures, the natural fiber components (cellulose, hemicellulose, and lignin) start to degrade and their major properties (mechanical and thermal) change. Different methods are used in the literature to determine the thermal properties of natural fiber composites as well as to help to understand and determine their suitability for a certain applications (e.g., Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and differential mechanical thermal analysis (DMA)). Weight loss percentage, the degradation temperature, glass transition temperature (T_g), and viscoelastic properties (storage modulus, loss modulus, and the damping factor) are the most common thermal properties determined by these methods. This paper provides an overview of the recent advances made regarding the thermal properties of natural and hybrid fiber composites in thermoset and thermoplastic polymeric matrices. First, the main factors that affect the thermal properties of natural and hybrid fiber composites (fiber and matrix type, the presence of fillers, fiber content and orientation, the treatment of the fibers, and manufacturing process) are briefly presented. Further, the methods used to determine the thermal properties of natural and hybrid composites are discussed. It is concluded that thermal analysis can provide useful information for the development of new materials and the optimization of the selection process of these materials for new applications. It is crucial to ensure that the natural fibers used in the composites can withstand the heat required during the fabrication process and retain their characteristics in service.

Effect of Fibre Surface Treatment and Nanofiller Addition on the Mechanical Properties of Flax/PLA Fibre Reinforced Epoxy Hybrid Nanocomposite

Natural fibre-based materials are gaining popularity in the composites industry, particularly for automotive structural and semi-structural applications, considering the growing interest and awareness towards sustainable product design. Surface treatment and nanofiller addition have become one of the most important aspects of improving natural fibre reinforced polymer composite performance. The novelty of this work is to examine the combined effect of fibre surface treatment with Alumina (Al₂O₃) and Magnesia (MgO) nanofillers on the mechanical (tensile, flexural, and impact) behaviour of biotex flax/PLA fibre reinforced epoxy hybrid nanocomposites. Al₂O₃ and MgO with a particle size of 50 nm were added in various weight proportions to the epoxy and flax/PLA fibre, and the composite laminates were formed using the vacuum bagging technique. The surface treatment of one set of fibres with a 5% NaOH solution was investigated for its effect on mechanical performance. The results indicate that the surface-treated reinforcement showed superior tensile, flexural, and impact properties compared to the untreated reinforcement. The addition of 3 wt. % nanofiller resulted in the best mechanical properties. SEM morphological images demonstrate various defects, including interfacial behaviour, fibre breakage, fibre pullout, voids, cracks, and agglomeration.

Development and Characterization of a 3D Printed Cocoa Bean Shell Filled Recycled Polypropylene for Sustainable Composites

Natural filler-based composites are an environmentally friendly and potentially sustainable alternative to synthetic or plastic counterparts. Recycling polymers and using agro-industrial wastes are measures that help to achieve a circular economy. Thus, this work presents the development and characterization of a 3D printing filament based on recycled polypropylene and cocoa bean shells, which has not been explored yet. The obtained composites were thermally and physically characterized. In addition, the warping effect, mechanical, and morphological analyses were performed on 3D printed specimens. Thermal analysis exhibited decreased thermal stability when cacao bean shell (CBS) particles were added due to their lignocellulosic content. A reduction in both melting enthalpy and crystallinity percentage was identified. This is caused by the increase in the amorphous structures present in the hemicellulose and lignin of the CBS. Mechanical tests showed high dependence of the mechanical properties on the 3D printing raster angle. Tensile strength increased when a raster angle of 0° was used, compared to specimens printed at 90°, due to the load direction. Tensile strength and fracture strain were improved with CBS addition in specimens printed at 90°, and better bonding between adjacent layers was achieved. Electron microscope images identified particle fracture, filler-matrix debonding, and matrix breakage as the central failure mechanisms. These failure mechanisms are attributed to the poor interfacial bonding between the CBS particles and the matrix, which reduced the tensile properties of specimens printed at 0°. On the other hand, the printing process showed that cocoa bean shell particles reduced by 67% the characteristic warping effect of recycled polypropylene during 3D printing, which is advantageous for 3D printing applications of the rPP. Thereby, potential sustainable natural filler composite filaments for 3D printing applications with low density and low cost can be developed, adding value to agro-industrial and plastic wastes.

Development and Analysis of Mechanical Properties of Caryota and Sisal Natural Fibers Reinforced Epoxy Hybrid Composites

In recent years, natural fiber reinforced polymer composites have gained much attention over synthetic fiber composites because of their many advantages such as low-cost, light in weight, non-toxic, non-abrasive, and bio-degradable properties. Many researchers have found interest in using epoxy resin for composite fabrication over other thermosetting and thermoplastic polymers due to its dimensional stability and mechanical properties. In this research work, the mechanical and moisture properties of Caryota and sisal fiber-reinforced epoxy resin hybrid composites were investigated. The main objective of these studies is to develop hybrid composites and exploit their importance over single fiber composites. The Caryota and sisal fiber reinforced epoxy resin composites were fabricated by using the hand lay-up technique. A total of five different samples (40C/0S, 25C/15S, 20C/20S, 15C/25S, 0C/40S) were developed based on the rule of hybridization. The samples were allowed for testing to evaluate their mechanical, moisture properties and the morphology was studied by using the scanning electron microscope analysis. It was observed that hybrid composites have shown improved mechanical properties over the single fiber (Individual fiber) composites. The moisture studies stated that all the composites were responded to the water absorption but single fiber composites absorbed more moisture than hybrid composites.

Ballistic Performance of Ramie Fabric Reinforcing Graphene Oxide-Incorporated Epoxy Matrix Composite

Graphene oxide (GO) incorporation in natural fiber composites has recently defined a novel class of materials with enhanced properties for applications, including ballistic armors. In the present work, the performance of a 0.5 vol % GO-incorporated epoxy matrix composite reinforced with 30 vol % fabric made of ramie fibers was investigated by stand-alone ballistic tests against the threat of a 0.22 lead projectile. Composite characterization was also performed by Fourier-transform infrared spectroscopy, thermal analysis and X-ray diffraction. Ballistic tests disclosed an absorbed energy of 130 J, which is higher than those reported for other natural fabrics epoxy composite, 74–97 J, as well as plain Kevlar (synthetic aramid fabric), 100 J, with the same thickness. This is attributed to the improved adhesion between the ramie fabric and the composite matrix due to the GO—incorporated epoxy. The onset of thermal degradation above 300 °C indicates a relatively higher working temperature as compared to common natural fiber polymer composites. DSC peaks show a low amount of heat absorbed or release due to glass transition endothermic (113–121 °C) and volatile release exothermic (~132 °C) events. The 1030 cm⁻¹ prominent FTIR band, associated with GO bands between epoxy chains and graphene oxide groups, suggested an effective distribution of GO throughout the composite matrix. As expected, XRD of the 30 vol % ramie fabric-reinforced GO-incorporated epoxy matrix composite confirmed the displacement of the (0 0 1) peak of GO by 8° due to intercalation of epoxy chains into the spacing between GO layers. By improving the adhesion to the ramie fabric and enhancing the thermal stability of the epoxy matrix, as well as by superior absorption energy from projectile penetration, the GO may contribute to the composite effective ballistic performance.