Reinforced Polymer Composites Research Articles

Extraction and characterization of novel cellulosic fiber from Jatropha integerrima plant stem for potential reinforcement in polymer composites

Extraction and characterization of novel cellulosic fiber from Jatropha integerrima plant stem for potential reinforcement in polymer composites

Influence of fiber orientation on the moisture adsorption of continuous bamboo fiber composites

Recently, a considerable interest is being shown in the use of plant fibers as reinforcement for polymer composites. Indeed, researchers and scientists are trying to overcome the environmental bias by using bio-composites in several engineering applications. Their attractive specific mechanical properties, low cost, lightness and biodegradability may promote them to substitute expensive and non-renewable fibers such as carbon, kevlar and glass fibers. However, the hydrophilic behavior of natural fibers is of a great concern for their possible outdoor applications. Indeed, the entrapment of water molecules at the fiber lumen, voids and porosities may reduce the tensile strength and modulus of plant fiber composites. Hence, this work aims to evaluate the moisture adsorption behavior of bamboo fiber epoxy composites at different fiber orientations (tangential and radial directions). Firstly, bamboo fibers are extracted using a combination of compression and manual techniques. Morphological and thermogravimetric analyses are carried out to deeply understand the physical properties of the extracted fibers. The findings show that the fibers consist of parallel microfibrils enclosed by some impurities and amorphous constituents. The moisture content of bamboo fibers at 50RH% is deduced from the moisture evaporation stage in the thermogravimetric curve and is about 8.07%. Thereafter, hand layup and compression techniques are used to manufacture the composite samples for the moisture adsorption test. The obtained results show that the equilibrium moisture capacity and diffusion rate values are higher along the fiber direction, which is mainly due to the exposure of the fiber lumen and interfacial voids. The mechanism of moisture transport into composites is found to follow Fick’s law.

Investigation into the mechanical characteristics of natural fiber-reinforced polymer composites: Effects of flax and e-glass reinforcement and stacking configuration

Glass fibers are commonly used to reinforce polymer composites due to their excellent mechanical properties. However, their production is expensive and environmentally unfriendly. To tackle these concerns, researchers are exploring natural fibers as a substitute reinforcement material for polymer composites. These natural fiber-reinforced polymer composites are lightweight, possess a high strength-to-weight ratio, and are biodegradable, making them attractive for a wide range of applications such as automotive, marine, oil, consumer goods, sporting goods, and biomedical fields. In this study, the hybrid effects of using flax and E-glass as reinforcement in epoxy, as well as the stacking configuration of flax/E-glass, on the mechanical properties of the polymer composites were investigated. Laminates with different fiber loadings were created using hand layup vacuum bagging and then subjected to tensile testing following ASTM standards. Statistical analysis tools such as interval graphs, contour plots, surface plots, probability plot, and Pareto chart were employed to assess the impact of the fiber and other parameters. Regression analysis was conducted to develop an empirical equation with a 95 percent confidence limit for all intervals. The results indicated that the properties of the polymer composites exhibited slight improvement from pure epoxy to flax/epoxy composites, significant improvement with E-Glass/epoxy composites, and slight decrease with hybridization. Nevertheless, the hybrid composite still demonstrated much higher tensile strength compared to the pure and flax/epoxy composites. The stacking configuration with treated flax as the core and E-Glass as the skin layer resulted in a tensile strength of 164.23 MPa, surpassing that of flax/epoxy and pure epoxy composites. In conclusion, for medium load structural applications, flax/E-glass/reinforced epoxy composites are recommended through hybridization. The utilization of natural fibers as reinforcement in polymer composites presents a cost-effective and environmentally friendly alternative to glass fibers, while still providing the necessary mechanical properties for various applications.

Flexural response of 3D printed wood dust reinforced polymer composite

BackgroundThe rising environmental concern and inadequacy of conventional resources have led to increasing demand for new bio composite materials for various products and as a unique substitute for traditional and petroleum-based materials for different applications. The major constraint in most conventional bio composites manufacturing techniques is a mold or complex setup requirement, which leads to a lengthy manufacturing process. 3D printing manufacturing technique has extended a huge attention in current years because of its simplicity in manufacturing complex geometries. Problem StatementThis work is aimed to determine the flexural response of 3D printed wood –PLA composite. MethodDue to PLA's low mechanical properties, wood dust had added to enhance the properties. 22 wt% Wood dust filled PLA filament is procured with a 1.75 mm diameter. Five test samples have been printed with the fused deposited 3D printing technique. The flexural behavior – flexural strength, flexural Strain and flexural modulus, of the developed material, was tested with the help of a universal tensile testing machine. ResultsThe test results revealed the maximum flexural strength of the material is 36 MPa with a maximum Strain of 3.55% and modulus of 1.4 GPa. ConclusionWood dust acts as a filler and has improved the material’s flexibility, also, wood particles make the material porous and that affect the interfacial adhesion between wood and PLA polymer in 3D printing which reduce the strength.

Investigation of mechanical, thermal and water absorption behaviour of MWCNT’s with AL2O3 reinforced polymer composite

In this work, composite materials were developed using compression moulding method, which the composition of M2A1C (Epoxy + 2 wt % MWCNT +1 wt % Al2O3), M2A1.5C (Epoxy + 2 wt % MWCNT +1.5 wt % Al2O3) and M2A1C (Epoxy + 2 wt % MWCNT +2 wt % Al2O3). From the composition, M2A1.5C had improved the mechanical properties of 30%, 24% and 28% in tensile strength, flexural strength and impact strength, respectively, compared to the M2A1C. From the thermo-gravimetric examination, the critical change was happened during increasing of Al2O3, however, the M2A1.5C had a significant improvement within the residual mass and maximum temperature decomposition with compared to other composites. Hydrophobicity decreased in the M2A1C composition, due to the low density of the material in the composite. The study is exploring ways to improve the polymer-metal matrix hybrid composite materials to make them lighter and more affordable, as well as easier to use in light load applications.

Effects of nanoparticles on the mechanical and thermal behavior of fiber reinforced polymer composites – A review

Composite materials have a long track record of success. A lot of work is always being done to improve the use of composite materials because they are now a significant concern for the scientific community on a global scale. For Fiber Reinforced Polymer (FRP) composite materials, epoxy resin has recently proven to be a good choice for building high-performance polymeric composites. Up till now, a range of nano fillers comprised of carbon nanotubes and graphene nano-platelets, clay and oxide nanoparticles have been employed to improve mechanical characteristics. The impact of nanoparticles (heat-resistant fillers like graphene, silicon carbide, and aluminum oxide) regarding the structural and morphological behavior of epoxy composites will be studied as a result of the extensive development and research in this sector. This work intends to investigate the outcomes and findings of previous Mechanical and thermal properties on composite materials. There is also a discussion of the properties evaluation of the various composite laminates. The study's findings could lead to the design and fabrication of a material with superior mechanical properties, which would fundamentally alter how composite materials are used.

Mechanical properties evaluation of carbon nanotube/sisal fiber/marble dust reinforced polymer based composites

In current circumstances the use of natural fibers is improved extremely in vehicle segment as prospective renewable and biodegradable constituents. The automotive industry currently uses natural fibre reinforced polymer composites for a wide range of panelling components in wagons, as well as for several interior components. It's a plastic that can stand in for glass-fiber-reinforced varieties when necessary. This study focusses on how marble dust and multi-walled carbon nanotubes scatter in sisal fibre and epoxy. The composite was made using 1 wt% marble dust particles and 0, 0.5, 1, 1.5, and 2 wt% of multi-walled carbon nano tube (CNT). Mechanical parameters were determined using ASTM-standard testing process, and test composites were cut to those specifications. The results proved that the nanotube composite with a 1.5 wt% increase in nanotubes possessed improved mechanical properties. Adding 1.5% carbon nanotubes increased tensile strength by 12.14%, and adding 2% CNT increased tensile strength by 14.85%. Meanwhile, flexural strength improved by 72.6% and 124.8%, respectively, after the addition of CNT at the indicated weight percentages to preserve their dimensional stability.

Flammability and morphology of Agel leaf fibre- epoxy composite modified with carbon powder for fishing boat applications

Fibre Reinforced Polymer Composites have been extensively developed to construct fishing vessels. This study reports on the successful development of the Agel Leaf Fibre (ALF)-Epoxy composite reinforced with carbon powder and fabricated using the Vacuum Infusion method.The composites were prepared by varying the carbon powder filler content at volumes of 0%, 10%, and 30%. The fire resistance of the composites was investigated using a burning test according to ASTM D-3014 standards. The morphology of the composites was observed through SEM analysis and analysed using ImageJ software.The research findings reveal that adding 30% carbon powder in the HCP composite reduced the burning rate by 42.624 mm/sec and the time to ignition by 17.33 seconds, indicating improved fire resistance properties. The carbon powder inhibited flame propagation and reduced the combustion rate by 0.49%. The SEM examination confirmed that the fibre porosity decreased, resulting in a denser composite with enhanced fibre-matrix adhesion. Therefore, the implementation of fire-resistant composite materials in fishing vessel construction can be realised.The present study primarily examined the immediate effects of carbon powder additions on the morphology of the composites. However, it is crucial to consider these composites’ long-term stability and durability. Future research should investigate the ageing behaviour, considering environmental factors such as humidity, temperature, and UV radiation, to assess their impact on the morphology and flammability resistance of the composites. Additionally, it is essential to acknowledge that other factors, including fibre orientation, fibre length, and matrix properties, can significantly influence the overall performance of the composites.The enhanced flammability resistance of Agel Leaf Fibre-Epoxy composites with carbon powder additions holds significant benefits for fishing boat applications. In marine environments, the risk of fire incidents on fishing boats is high, making materials with good fire resistance highly desirable. Therefore, implementing fire-resistant composite materials in fishing boat construction can be realised to reduce the risk of fire incidents in high-seas fishing vessels.Composites with added carbon powder exhibited smaller flames, slower burning rates, and a lack of significant flame propagation. This suggests that adding carbon powder acts as an oxygen barrier and reduces the availability of fuel within the composite.

Thermally recyclable and reprocessable glass fiber reinforced high performance thermosetting polyurethane vitrimer composites

Glass fiber reinforced polymer composites (GFRPCs) based on thermoset polymer have been deployed in a variety of industrial sectors. However, a major drawback of thermoset polymeric composites is their significant contributions to waste and environmental pollution due to the challenges in recycling, reprocessing, and reutilization. Here, a sustainable thermosetting polyurethane vitrimer is developed by forming dynamic aromatic disulfide bonds. The obtained polyurethane vitrimer exhibits good mechanical properties and remarkable reprocessability. Under a large deformation or pulverizing, it can completely restore to its original mechanical properties of 30 MPa of strength and 407% elongation at break by 5-minute thermal reparation at 100 °C. Moreover, the unique properties of the polyurethane vitrimer enables a novel technology for processing GFRPCs, namely “blocks-building” process, in which the fully cured single-layer prepregs could be effectively integrated into multiple layers.

Investigations on 355 nm picosecond laser machining of carbon fiber reinforced polymer composites

Carbon fiber reinforced polymer (CFRP) composites have emerged as excellent performance structural materials with a wide range of applications in the aerospace industry. Ultrafast laser is a promising and versatile tool for manufacturing these composites due to its advantages of high peak intensity and ultrashort pulse duration. Herein, a theoretical model based on the Fokker–Planck law and the two-temperature equation, i.e. the ultrafast responses of a two-dimensional heterogeneous material assembly of resin matrix padded with carbon fiber reinforced phase irradiation by 355 nm picosecond laser is established. The evolution of laser-excited free electron density is analyzed, and the relationship between the optical properties of substrate and electron density is revealed. The spatial and temporal distribution of electron and lattice temperatures are thus characterized. The ablation thresholds of resin and carbon fiber are determined, the accuracy of which are verified by experiments. On this basis, orthogonal experiments are conducted to analyze the influence law of process parameters on the ablation depth and heat affected zone (HAZ) width. Optimized parameter groups are discovered to realize the high-quality machining of CFRP composite with considerable depth-to-width ratio and limited HAZ width. This work offers new insight into the fundamental regimes and high-quality machining for picosecond laser manufacturing of CFRP composites.

Effect of natural fillers as reinforcements on mechanical and thermal properties of HDPE composites

Demand for natural fibers has increased in recent years due to the requirement for biodegradable materials. Owing to the increasing awareness on the overuse and over-dumping of plastics in the environment, the current work focused on a solution by using tree leaves as a particulate reinforcement which is one of the common waste products of trees. In this regard, Norfolk pine (NOP) tree leaf particulates filled High-Density Polyethylene (HDPE) composites were fabricated through injection moulding technique with different filler weight % of 0, 10, 20, 30, 40, and 50 wt. %. The study of the crystalline structure of the fillers and the detection of functional compounds in the materials were carried out through X-ray diffraction (XRD) and Energy dispersive X-ray spectroscopic (EDX) analysis. Tensile strength, compressive strength, and flexural strength of the fabricated composite specimens were also assessed. Results revealed that the mechanical properties of the 30 wt. % pine tree leaf-filled HDPE composites were found to be superior when compared to pure HDPE composites. The failure surface morphology of the composite samples was examined using scanning electron microscopy (SEM). The melting point and decomposition of 30 wt. % NOP leaf particulate-filled HDPE composites specimen, whose mechanical properties were higher, were examined using thermo-gravimetric analysis (TGA) and differential scanning calorimetry (DSC). From the results, it was found that NOP fillers can be used as an effective reinforcement in polymer composites.

Numerical Modeling of Low-Velocity Impact on Composite Laminates

The response over the low-velocity impact of various shape impactors on a glass fiber reinforced polymer composite has been numerically analyzed with a hemispherical, flat, partially flat and truncated shaped impactor used to analyze the behavior of resistance of a GFRP composite at various speeds. The numerical analysis was carried out using finite element analysis software, ABAQUS (Dynamic/Explicit). To assess the response of the composite laminates while impacting, finite element models were developed. The Hashin failure criteria were used to represent braided glass-fiber reinforced composite plate damage. Regarding projectile shape, the impact reaction of the composite was examined. The results also show that the mechanical response of woven glass fiber polymer composite under low-velocity projectile impact largely depends on the impactor’s nose shape and the velocity of the impactor.

Addition of silica in the adhesive primer layer of composite systems used to repair leak defects in metallic pipelines

Fibre reinforced polymer composites are often used to repair through-thickness corrosion damage in metal pipes. Usually, a primer adhesive layer is initially applied to the surface of the pipe and then the composite reinforcement is applied in concentric layers. This paper investigates the possibility of adding silica as a low-cost thixotropic thickener to a commercial epoxy resin to facilitate the application of the prime layer while maintaining the strength and effectiveness of the repair after curing. The study of the influence of the silica concentration on the rheological behaviour of the adhesive before fully cured was performed using a rheometer. A preliminary study about the influence of different fractions of silica on the rupture force of metal-composite hybrid bonded joints after full cure showed a good result with the concentration of 1% by weight of epoxy resin. Then, hydrostatic burst tests were carried out on specimens with through-thickness defects, repaired using the same composite, but with two different initial adhesive layers (same surface finish and layer thickness, but with silica and without silica). The study shows that introducing a low fraction of silica facilitates the application of the primer and does not significantly affect the strength of the repair.

Evaluation of drilling characteristics to explore the effect of graphene nanoplatelets on glass fiber reinforced polymer composite

The objective of the present study is to explore the influence of graphene nanoplatelets having various wt%, spindle speed (SS), and feed rate (FR) on damages caused due to drilling of glass fiber reinforced polymer (GFRP) laminates. The findings showed that when the concentration of graphene grows up to 0.25 wt%, it enhances the mechanical properties of the composite. After that, it starts to decrease. Experiments proved that interlaminar shear strength (ILSS), flexural strength, and tensile strength of the graphene-embedded (0.25 wt%) composite rose by 18.49 %, 25.15 %, and 14.79 %, respectively, as compared to neat GFRP composite. A minimum surface roughness (2.1393 µm), thrust force (622.62 N), torque (2.0155 Nm), entry delamination factor (1.1556), and exit delamination factor (1.2218) were attained in 0.25 wt% graphene-embedded GFRP composite. An increase in SS and a reduction in FR led to optimizing the composites' machining performances. Lastly, FESEM was used to examine the damage on the drilled surfaces.

Mechanisms for Introduction of Pseudo Ductility in Fiber Reinforced Polymer Composites- A Review

Advanced polymer matrix composites are gaining the market in their way due to their exceptional specific stiffness, specific strength, fatigue, and corrosion resistance in the field of Auto-Tech, Aero-Tech, Biotech, etc. However, the lack of ductility and catastrophic failure has limited their application in these areas. Hence there is a need to explore means and protocols for designing the reduced factor of safety with high-performance toughened composites. To address this problem, a new generation of high-performance composites with pseudo-ductile or ductile behavior is needed. The ongoing High-Performance Ductile Composite Technology (HiPerDuCT) program jointly between the University of Bristol U.K and Imperial College London to address this challenge by developing newer materials. The fiber architectures made under this project gave a more gradual failure rather than catastrophic failure which improves the mechanical properties. This paper mainly focuses on addressing this evolution of pseudo ductility in fiber-reinforced composites. In addition to this, an attempt has been made to newer possible fiber positions in matrix materials for inducing reasonable ductility in composites.

Technical wood wool for composites

Due to its very good mechanical properties at low density, wood is a high potential and sustainable raw material for composite applications. Wood as small particles are commonly processed with polymers to Wood-Polymer-Composites (WPC). Thereby, the inherent strength of the wood is not used to its full potential. In order to transfer the strength properties of solid wood with good shaping properties to composite, wood wool properties were studied. Wood wool is a well-known raw material in the wood-processing industry and is mainly used for packaging, animal bedding and insulation boards [1, 2]. The use of wood wool as a flexible, formable reinforcement for polymer composites is not known so far. Therefore industrial wood wool and developed experimental wood wool are investigated and evaluated for their suitability as fibre reinforcement for composites. The mechanical properties, in particular the tensile strength, are the relevant factors.

Effect of curvature and stacking sequence on flexural strength in glass fiber reinforced composites

Abstract Most of the structures in vehicles used in the automotive, aviation, and marine industries are exposed to different loads. It is seen that these structures are more exposed to flexural stress. Structures can sustain dangerous damage over time under the effects of flexural loads. The resistance of curved glass fiber reinforced polymer composites to flexural force is very important. In this study, the diameters of curved composites of 760 mm, 380 mm, and 304 mm are studied. Also, fiber stacking sequences were determined as [0/0/−45/+45/90/90]S and [90/90/−45/+45/0/0]S and compared. All specimens were produced by vacuum infusion method. Three-point flexural tests were performed according to the ASTM D7264 standard at 1 mm∙min−1 punch speed. Among all composites, 760 mm diameter and Type 2 stacking were found to have the highest flexural strength. Hence, it was observed that the flexural strength decreased with the increase in curvature, and Type 2 fiber layer sequencing is more durable than Type 1 sequencing. This is because the 90° fiber direction in the substrate has a damping effect on the applied force.

Tribo-Mechanical Investigation of Glass Fiber Reinforced Polymer Composites under Dry Conditions.

Tribo-mechanical experiments were performed on Glass Fiber Reinforced Polymer (GRFP) composites against different engineering materials, and the tribological behavior of these materials under dry conditions was investigated. The novelty of this study consists of the investigation of the tribomechanical properties of a customized GFRP/epoxy composite, different from those identified in the literature. The investigated material in the work is composed of 270 g/m2 fiberglass twill fabric/epoxy matrix. It was manufactured by the vacuum bag method and autoclave curing procedure. The goal was to define the tribo-mechanical characteristics of a 68.5% weight fraction ratio (wf) of GFRP composites in relation to the different categories of plastic materials, alloyed steel, and technical ceramics. The properties of the material, including ultimate tensile strength, Young's modulus of elasticity, elastic strain, and impact strength of the GFPR, were determined through standard tests. The friction coefficients were obtained using a modified pin-on-disc tribometer using sliding speeds ranging from 0.1 to 0.36 m s-1, load 20 N, and different counter face balls from Polytetrafluoroethylene (PTFE), Polyamide (Torlon), 52,100 Chrome Alloy Steel, 440 Stainless Steel, and Ceramic Al2O3, with 12.7 mm in diameter, in dry conditions. These are commonly used as ball and roller bearings in industry and for a variety of automotive applications. To evaluate the wear mechanisms, the worm surfaces were examined and investigated by a Nano Focus-Optical 3D Microscopy, which uses cutting-edge μsurf technology to provide highly accurate 3D measurements of surfaces. The obtained results constitute an important database for the tribo-mechanical behavior of this engineering GFRP composite material.

Accelerated aging of polymer composite from Pennisetum purpureum fibers with recycled low-density polyethylene

The use of natural fibers (NF) as reinforcement in polymer composites have been an interesting option to improve their mechanical properties and to decrease production costs since several crops can produce large amounts of NF with low cost. This is particularly attractive for polymer waste recycling that depends of the production of cheap materials to be economically viable. Elephant grass ( Pennisetum purpureum schum) is a tropical climate plant of fast growth with high potential for production of NF. However, studies on the use of P. purpureum fibers as reinforcement in polymers, mainly for recycled polymers, have been restricted. The aims of this study was to evaluate the action of the P. purpureum fibers on the properties of composites using matrix of low-density polyethylene waste (LDPE-w) as well as to verify the behavior of recycled polymer when submitted to the accelerated photochemical aging using UVA radiation. LDPE-w and LDPE-w composite with P. purpureum fibers (LDPE-composite) were analyzed at different aging times by tensile and impact tests, melt flow rate, scanning electron microscopy and Fourier transform infrared. It was verified that P. purpureum fibers induce defects in matrix of LDPE-w, decreasing the performance of mechanical properties. Similar effect also occurs when LDPE-w is submitted to the first hours of accelerated aging. On the other hand, effects of stabilization of the degradation on the polymer matrix can be attributed to the P. purpureum fibers at high aging times. Thus, P. purpureum presents high potential for use as reinforcement in recycled thermoplastic waste.

A novel approach to extract and characterize vacuum-pressurized bamboo fibers using mechano-chemical techniques

This current study aims to extract bamboo fibers from different species of bamboo using the mechanochemical method and investigate their properties. The bamboo species used in this study were Dendrocalamus, Bambusa balcoaa, Oliveri, Asamica, and Chimono. The vacuum-pressurized impregnation treatment process was employed for treating the bamboo. The mechanochemical method was chosen for extracting the bamboo fibers due to its simplicity and efficiency. The yield percentage of the bamboo fibers was determined. X-ray diffraction (XRD) analysis showed an increase in the crystallinity of the bamboo fibers with subsequent treatments in the presence of NaOH, as evidenced by two well-defined peaks at 2θ = 17.6° and 2θ = 22.7°. FTIR analysis revealed the presence of numerous hydroxyl groups in the bamboo fibers, indicated by the –OH expanding and contracting vibration at the band around 3311 cm−1. Thermal gravimetric analysis (TGA) was conducted to investigate the thermal stability of the bamboo fibers, and the results demonstrated that chimino bamboo fiber exhibited the highest level of thermal stability compared to other treated bamboo fibers. Scanning electron microscopy (SEM) was employed for morphological characterization, providing insights into the surface morphology of the bamboo fibers. Based on the findings, it can be inferred that bamboo fibers, particularly of the chimino type, have the potential to serve as a viable reinforcement in polymeric composites for lightweight applications in various industries, such as automotive, aerospace, and packaging.