Fiber Sheet Research Articles

Thermal Properties of Carbon Nanofiber Sheet for Thermal Interface Materials under High Temperature and Humidity

In this study, polyvinyl alcohol (PVA) - polytetrafluoroethylene (PTFE) - vapor grown carbon fiber (VGCF) sheets are fabricated as a new paper-like thermal interface material (TIM), which is a potential substitute for traditional TIMs. Two types of PVA-PTFE-VGCF sheets were fabricated by using 120 nm and 300 nm PTFE particles. The microstructure shows that the VGCFs were arranged in random directions inside the sheet and interconnected via the aggregate of PVA. 300 nm PTFE particles were well distributed within the sheet, while 120 nm PTFE particles aggregated partially and formed pores nearby. The fabricated sheets have a low thickness of 31.2 um and 28.2 um, and lightweight properties with a density of 0.79 × 106 g·m−3 and 0.91 × 106 g·m−3, respectively. With the addition of 300 nm PTFE particles, the fabricated sheet has higher thermal conductivities of 9.81 W·m−1·k−1 in the in-plane direction and 2.11 W·m−1·k−1 in the through-plane direction. In the high temperature and humidity test, the thermal conductivities of the fabricated sheet were increased due to the rearrangement of PVA and PTFE particles.

Effect of enzymatic treatment on Eucalyptus globulus vessels passivation

Hardwood vessel elements generate problems in industrial uncoated wood-free printing paper operation, causing vessel picking and ink refusal. These problems are mitigated using mechanical refining at the cost of paper quality. Vessel enzymatic passivation, altering its adhesion to the fiber network and reducing its hydrophobicity is a way of improving paper quality. The object of this paper is to study how the enzymatic treatment by xylanase and by an enzymatic cocktail containing cellulases and laccases affect elemental chlorine free bleached Eucalyptus globulus vessel and fiber porosities, bulk, and surface chemical compositions. Thermoporosimetry revealed the vessel structure to be more porous, surface analysis showed its lower O/C ratio and bulk chemistry analysis its higher hemicellulose content. Enzymes had different effects on porosity, bulk and surface composition of fibers and vessels, affecting vessel adhesion and hydrophobicity. Vessel picking count decreased 76% for papers containing vessels treated with xylanase and 94% for the papers with vessels treated with the enzymatic cocktail. Fiber sheet samples had lower water contact angle (54.1º) than vessels rich sheets (63.7º), that reduced with xylanase (62.1º) and cocktail (58.4º). It is proposed that differences in vessel and fiber porosity structures affect the enzymatic attacks, eventually causing vessel passivation.

Reinforcing interlaminar interface of carbon fiber reinforced metal laminates by graphene

Fiber metal laminas (FMLs) are disadvantaged by weak interlaminar strength limiting their application where dynamic loads are expected. In this study, graphene platelets (GnPs) were employed to strengthen the interlaminar interface in carbon fiber (CF) metal laminates. GnPs within range of 0–1 wt% were added into epoxy resin via ultrasonication. GnPs-based FML samples were prepared by wet lay-up method and tested under flexural loading, short beam shear and single lap shear. The reinforcing mechanism and failure modes were investigated. The results show that 0.5 wt% of GnPs increases the flexural strength and interlaminar shear strength by 39.7% and 53.2%, respectively. In addition, molecular dynamics (MD) simulations concluded that the addition of low content of GnPs increases the elastic modulus of the matrix and improves the resin adsorption on the surface of carbon fiber and Al sheets. The results from both the experimental and MD simulation indicate that adding GnPs can effectively improve the interlaminar mechanical properties of FMLs. In principle, the research method in this paper can be applied to the study of FMLs with other nanomaterials.

Numerical Scrutinization of Ternary Nanofluid Flow over an Exponentially Stretching Sheet with Gyrotactic Microorganisms

In the modern age, the study of nanofluids over the stretching sheet has received much attention from researchers due to its significant role in the polymer industry, for instance in the production of fibre sheets and the extrusion of molten polymers through a slit die. Due to these affordable applications, the current study focusses on the motion of metallic ternary nanofluids (Ag-Au-Cu/H2O) past an exponential stretching sheet, taking diverse effects such as gyrotactic microorganisms, activation energy, buoyancy forces and thermal radiation into consideration. The model was created with the complex system of partial differential equations. Suitable similarity transformations and non-dimensional quantities were utilized to transform the complex system of partial differential equations to a set of ordinary differential equations. The resultant system is solved with the help of Matlab software. The computational outcomes are presented through the tables and pictorial notations. It is observed from the current analysis that the nanoparticle temperature of the ternary nanofluid enhances with the enhancement of activation energy and Brownian motion parameters. For the rising values of Lewis and thermophoresis numbers there is a declination in the nanoparticle concentration distribution. The Brownian motion and radiation effects increase the microorganism profile.

The structure of the eggshell and eggshell membranes of Crocodylus niloticus.

The macro- and microstructure, elemental composition, and crystallographic characteristics of the eggshell and eggshell membranes of the Crocodylus niloticus egg was investigated using optical and electron microscopy, energy-dispersive X-ray spectroscopy (EDS), electron backscatter diffraction (EBSD) and computerised tomography. The translucent ellipsoid egg is composed of two basic layers, the outer calcified layer referred to as the shell and an inner organic fibre layer, referred to as the shell membrane. The outer inorganic calcite shell is further divided into an external, palisade and mammillary layers with pore channels traversing the shell. The external layer is a thin layer of amorphous calcium and phosphorus, the underlying palisade layer consist of irregular wedge-shaped crystals composed calcite with traces of magnesium, sodium, sulphur and phosphorus. The crystals are mostly elongated, orientated perpendicular to the shell surface ending in cone-shaped knobs, which forms the inner mammillary layer. The elemental composition of the mammillae is like that of the palisade layer, but the crystal structure is much smaller and orientated randomly. The highest number of mammillae and shell pores are found at the equator of the egg, becoming fewer towards the egg poles. The shell thickness follows the same pattern, with the thickest area located at the equator. The eggshell membrane located right beneath and embedded in the mammillary layer of the shell; it is made up of unorganised fibre sheets roughly orientated at right angles to one another. Individual fibres consist of numerous smaller fibrils forming open channels that run longitudinally through the fibre.

Full Scale Evaluation of GFRP Confined Softwood after Long-Term Exposure to High Humidity Environment

Plantation softwood timber poles are associated with low natural durability, and it is also not clear what the effects of the high humidity environment on the long-term performance of composite action integrity of such a system. This paper presents a durability study for the proposed composite poles using (GFRP) glass fiber-reinforced polymer as a confinement system on wooden poles sourced from plantation softwood timber. Radiata pine poles of 6 m length were wrapped with multiple layers of 0°/90° woven roving biaxial E-glass fiber sheets through a wet layup process as confinement. The prepared GFRP softwood poles were then subjected to high humidity environmental conditions of up to 95 ± 2% relative humidity and 22 ± 2 °C temperature for a period of 30 months. Various lengths of confinement were considered in this study ranging from 0% to 70% of the span length. The poles had a span length of 5.4 m and were tested using a three-point bending test. Results showed that the proposed confinement system of GFRP-softwood provided a satisfactory long-term performance and the high humidity environment did not greatly affect the improvement in the mechanical performance that the GFRP system provided.

Evaluation of properties of hybrid laminated composites with different fiber layers based on Coir/Al2O3 reinforced composites for structural application

Hybrid composites produced using natural and synthetic fibers are sustainable alternative materials for different structural applications. Therefore, this study aimed to incorporate coir fiber, E-glass, synthetic fabric, and rubber sheet into epoxy matrix by adding alumina filler to the coir composite. The hand layup method was used to manufacture a hybrid laminates composite of coir/E-glass/synthetic fabric/rubber sheet with different stacking sequences. The tensile, flexural, impact, hardness properties, water absorption, and thickness swelling of the products were evaluated. Scanning electron microscopy was used to study the morphology of the fractured surfaces. The results showed that the hybridization fiber and filler can enhance the tensile properties of the products up to 280% as well as improve the water absorption performance and thickness swelling to 78%. The flexural properties decreased after the incorporation of the fiber layer to the coir/alumina composite. An increase was also observed in the flexural and impact properties after the synthetic fabric was replaced with a rubber sheet. This study revealed that the incorporation of fibers layers into a coir composite led to higher hardness resistance. Furthermore, SEM image and macroscopic fractography showed fiber breakage on the matrix, a brittle fracture of composites, and delamination failure between the rubber sheet and matrix during the bending test. Based on the results, coir/E-glass/synthetic fabric/rubber sheet hybrid composites with different layering sequences were appropriate for various structures applications.

Improved detection of subsurface defects through active thermography and ensembling techniques

Quality control and defect detection are major challenges in industrial environments. The localization of these defects is of crucial importance, as they can affect the performance of manufactured products and even the safety of people. Defect detection methods based on visual sensors and image processing are nowadays the most common approaches. To detect subsurface defects it is common to combine active thermography and deep learning. In this paper, PCT (Principal Components Thermography) is employed to enhance the SNR (signal-to-noise ratio), leading to a significant improvement in the results. Recent developments in this field apply deep learning models for semantic segmentation and object detection. However, the quality of the predictions is not enough to ensure that all quality controls are met. In this paper, a combination of semantic segmentation and object detection is proposed to increase the reliability of predictions. To carry out this combination, a working methodology and two new ensembling strategies are proposed. After comparing the results of the proposed combination with the results of using only semantic segmentation methods in a real industrial scenario, where carbon fiber sheets are used, it is found that the proposal improves the segmentation metrics by a 5% to a 24%. Thus the reliability of the predictions is improved.

Local delivery of tacrolimus using electrospun poly-ϵ-caprolactone nanofibres suppresses the T-cell response to peripheral nerve allografts

Objective. Repair of nerve gap injuries can be achieved through nerve autografting, but this approach is restricted by limited tissue supply and donor site morbidity. The use of living nerve allografts would provide an abundant tissue source, improving outcomes following peripheral nerve injury. Currently this approach is not used due to the requirement for systemic immunosuppression, to prevent donor-derived cells within the transplanted nerve causing an immune response, which is associated with severe adverse effects. The aim of this study was to develop a method for delivering immunosuppression locally, then to test its effectiveness in reducing the immune response to transplanted tissue in a rat model of nerve allograft repair. Approach. A coaxial electrospinning approach was used to produce poly-ϵ-caprolactone fibre sheets loaded with the immunosuppressant tacrolimus. The material was characterised in terms of structure and tacrolimus release, then tested in vivo through implantation in a rat sciatic nerve allograft model with immunologically mismatched host and donor tissue. Main results. Following successful drug encapsulation, the fibre sheets showed nanofibrous structure and controlled release of tacrolimus over several weeks. Materials containing tacrolimus (and blank material controls) were implanted around the nerve graft at the time of allograft or autograft repair. The fibre sheets were well tolerated by the animals and tacrolimus release resulted in a significant reduction in lymphocyte infiltration at 3 weeks post-transplantation. Significance. These findings demonstrate proof of concept for a novel nanofibrous biomaterial-based targeted drug delivery strategy for immunosuppression in peripheral nerve allografting.

Rehabilitation of defective connections between two precast concrete segments (experimental and analytical study)

Connections in precast concrete elements are essential for improving the structures' utilization, cost, and quality control. Moment connection in beams was one of the easiest ways to achieve good performance of the structures by eliminating the plastic hinges zone. Due to constructing precast elements, some of them can be defective. This paper presents an experimental and analytical study to rehabilitate defective connections between two precast concrete segments. Six simply supported beams with beam-to-beam connections and one simply supported beam without connections, each with dimensions of 200 × 400 × 1600 mm, were fabricated and loaded to failure with a four-point load. The main variables parameters were a) the type of concrete mix in the splice region, two types of concrete were employed: Normal Strength Concrete (NSC) and High Strength Concrete (HSC) b) effect of rehabilitation techniques with using NSC in the connection zone such as; using warped fiber sheets around splice region or Carbon Fiber Reinforcement Polymer CFRP laminates at the tension surface of the tested beams c) effect of rehabilitation techniques with using HSC in the connection zone. Also, a new model was proposed based on some codes and guidelines of beams strengthened with Externally Bonded FRP Systems to calculate the flexure capacity for rehabilitating the beam-to-beam connections. The results indicate that neither casting NSC nor the HSC at the connection region has any effect on increasing the beam's capacity and cannot be used only as a rehabilitation technique in beam-to-beam connection. The fiber sheet warped around the splice region constructed from either NSC or HSC did not significantly increase the beam's capacity compared to rehabilitated beams with casting concrete only in the connection region. The load capacity of the rehabilitated beam with CFRP laminates and warped fiber sheets is increased significantly by about 122 % and 209 % compared to rehabilitated beams with splice regions constructed from NSC and HSC, respectively. The proposed model based on CNR-DT 200 R1/2013 equation gave a good prediction of the capacity of the rehabilitation connection for rehabilitated beams with CFRP laminates and warped fiber sheets.

Experimental study on the compression behavior of long timber column strengthened with the novel hybrid fiber sheets

Long timber columns are widely used in traditional timber structures worldwide; however, many of them possess bearing capacity issues and have to be strengthened. The current study aims to develop the novel Hybrid fiber reinforced polymers (HFRP) sheets suitable for long timber columns. In the first stage, six HFRP sheets were designed, and the evaluation of these sheets was carried out by the tensile tests and the Scanning electron microscopy (SEM) tests. Secondly, for the compression test, two sets of 36 timber columns were designed utilizing six types of HFRP sheets. Finally, the effects of different sheet types and strengthening methods on the compressive performance of timber columns were investigated. The findings reveal that bidirectional HFRP sheets have excellent compressive performance for timber columns. In the case of using one-layer interval reinforcement, the bearing capacity can be increased by 22.27%, which is 12.15–17.81% higher than that of the unidirectional HFRP sheets. Compared with one-layer reinforcement, the two-layer reinforcement increased from 0.91% to 5.35%. The current study's findings are intended to provide an essential scientific foundation for the advancement of fiber-reinforced timber column technology and the preservation of the heritage of timber structures.

Quantitative Analysis of Clot Deposition on Extracorporeal Life Support Membrane Oxygenators Using Digital and Scanning Electron Microscopy Imaging Techniques.

Device-induced thrombosis remains a major complication of extracorporeal life support (ECLS). To more thoroughly understand how blood components interact with the artificial surfaces of ECLS circuit components, assessment of clot deposition on these surfaces following clinical use is urgently needed. Scanning electron microscopy (SEM), which produces high-resolution images at nanoscale level, allows visualization and characterization of thrombotic deposits on ECLS circuitry. However, methodologies to increase the quantifiability of SEM analysis of ECLS circuit components have yet to be applied clinically. To address these issues, we developed a protocol to quantify clot deposition on ECLS membrane oxygenator gas transfer fiber sheets through digital and SEM imaging techniques. In this study, ECLS membrane oxygenator fiber sheets were obtained, fixed, and imaged after use. Following a standardized process, the percentage of clot deposition on both digital images and SEM images was quantified using ImageJ through blind reviews. The interrater reliability of quantitative analysis among reviewers was evaluated. Although this protocol focused on the analysis of ECLS membrane oxygenators, it is also adaptable to other components of the ECLS circuits such as catheters and tubing. Key features • Quantitative analysis of clot deposition using digital and scanning electron microscopy (SEM) techniques • High-resolution images at nanoscale level • Extracorporeal life support (ECLS) devices • Membrane oxygenators • Blood-contacting surfaces Graphical overview.

A study on mechanical and microstructure behaviour of carbon and glass fibre reinforced Al 2024-T3 laminated composite

Nowadays, usages of laminated composites have been extended to various applications such as automotive, aircraft and aerospace due to its high strength-weight ratio. Generally, aluminium alloys are developed using various casting techniques to achieve the required properties. However, laminated aluminium composites have received great attention among the scientist due to the weight reduction, the damping capacity they offer etc. In this present investigation, carbon and glass fibre laminated aluminium (Al2024-T3) composites are prepared by hand lay-up technique. Different form of aluminium structure namely sheet and mesh are used to fabricate − the composites. Different composites are prepared namely carbon fibre aluminium sheet laminate (CFASL), carbon fibre aluminium mesh laminate (CFAML), glass fibre aluminium sheet laminate (GFASL) and carbon fibre aluminium mesh laminate (GFAML). Effects of reinforcement of fibre on tensile, bending and flexural strength are studied. The microstructure of the composites is captured using scanning electron microscope (SEM) to study the failure mechanism. It was revealed that the CFASL and CFAML offered superior mechanical properties compared to the GFASL and GFAML. Higher tensile, bending and flexural strengths were obtained with carbon fibre and aluminium sheet laminated composites. They withstand the higher stresses due to less debonding and matrix cracking. Debonding and fibre breaking mechanisms observed in the glass fibre laminated composites caused reduced strength. CFASL composites showed superior mechanical properties followed by CFAML, GFASL and GFAML.

Composite magnetic sheet as sorbent for oil spill Clean-up

Water is the most vital resource required for the survival. But the cleanliness of this resource has been compromised in the form of oil spills which occurs due to the tanker disaster, transportation and storage of oil. It is extremely urgent to find the effective counter measure for oil spill treatment which aims oil spill-recovery strategy. Out of all the measures, development of a good biodegradable sorbent for spillage has sustained interest. To solve this environmental problem of oil spill, magnetic Sheet was synthesised by using lumen loading procedure using alkali treated bamboo fibers and cobalt ferrite nanoparticles (CoFe 2 O 4 ). Lumen loading permits the ferrite particles to be introduced solely into the lumens of bamboo fibres. For aiming this, CoFe 2 O 4 nanoparticles were first prepared by the sol–gel method and fibers were pre-treated with 6 % NaOH. Then synthesised ferrites were merged with the fibers. The samples were characterized by employing Scanning Electron Microscopy (SEM-EDS), Fourier transform infrared (FTIR), X-ray Diffraction (XRD). SEM confirms the deposition of cobalt ferrites nano particles on the surface and into the macropores of fibers. The sorption capacity for raw bamboo fibers, alkali treated bamboo fibers and composite sheet was calculated for three different type of oil such as mustard oil, coconut oil and olive oil. The sorption capacity shown by the raw bamboo fiber, 6 % NaOH treated bamboo fiber and composite magnetic sheet was in the range 1.8–2.2 g, 16.2–18.8 g and 1.8–2.4 g of oil per gram of sample respectively. The outcomes propose that the prepared magnetic sheet can be used as absorbent for oil-spill clean-up.

Investigation on the multiple plies structure of aluminum-lithium alloy and glass fiber composite with respect to deformation failure

The deformation behavior and mechanical properties based on the aluminum-lithium alloys (FMLs) was investigated to optimize the manufacturing process and further interface interaction. The primary structures of the FML composites were made with two sets of plies. From there, six secondary composites with different fibre sheet orientations were made. Then, interlaminar tensile, flexural, and peeling properties of FMLs were tested. The fiber orientation role in the case of failure behaviors of FMLs under different conditions was also revealed. The results have indicated that the plies design significantly enhanced the interlaminar properties of the FMLs and orientation of fiber laying has significantly affected the flexural strength. The peeling test has shown higher fiber-to-metal interfacial bonding with the value of ≥80 N m−2 over metal-to-metal adhesion. The plies increase the mechanical properties of composite based at fiber orientation and thickness, but too much impairs performance. The 3/2 plies showed a value of ≤385 MPa, which has better results in axial structure analysis than over 4/2 composite layers. The peak values appeared under different parameters like adhesive bonding and parallel fiber orientation, represented in the qualitative analysis section. The surface microscopy of aluminum-lithium alloy sheet and cross-section failure morphology of composite has been done at a different sighting. Surface characterization, fiber orientation breakdown, and deformation morphology have been studied concerning alloys’ elongated grains and micro pits.

КОМПЛЕКСНАЯ ОЦЕНКА ДЕФОРМАЦИОННОГО ПРОЦЕССА В УСИЛЕННЫХ УГЛЕПЛАСТИКОМ ЖЕЛЕЗОБЕТОННЫХ БАЛКАХ

The paper investigates the behavior of reinforced concrete beams reinforced with CFRP sheet under static loading. The experiment involved 22 large-scale samples – reinforced concrete beams with a size of 120х220х1290mm. One part of the specimens was reinforced with CFRP before loading, the other – under load after the appearance of the first cracks in concrete and their injection. The beams were loaded according to the 4-point bending scheme. The deformation state of the beams was assessed using strain gauge and deflection meter. The debonding of the carbon fiber sheet was evaluated by infrared thermography directly in the process of loading. The effect of CFRP on the bearing capacity and stiffness of beams reinforced before and during loading is evaluated. The ability of CFRP to restrain the opening of a crack was demonstrated. The effectiveness of the method of reinforcing beams with CFRP in combination with injection of cracks to restore the rigidity of the structure was evaluated. The pattern of crack formation in samples is presented. The influence of the quality of surface preparation on the nature of the debonding of carbon fiber and the features of cracking and destruction is shown. The parameters and features of CFRP debonding were determined for various debonding mechanisms. The parameters and intensity of CFRP debonding for beams reinforced in the unloaded state and under load are compared. The experimental values of debonding strains are compared with theoretical values determined by 8 known methods. It is shown that the actual deformation of CFRP debonding is 15-75% lower than the values calculated in accordance with Russian Building Codes SP 164.1325800.2014, and the fact of CFRP debonding does not determine the limiting state of the reinforced concrete beam in the presence of reliable anchoring of the longitudinal strip of the composite on supports.

A STUDY ON TSUNAMI-RESISTANT REINFORCEMENT EFFECT OF REINFORCED CONCRETE OUTER WALL BY FIBER REINFORCED SHEET

In the 2011 Tohoku Earthquake, many buildings were collapsed or overturned, and a number of outer concrete walls were broken by the hydro dynamic pressure due to Tsunamis. Out-of-plane strength of wall are usually not concerned in the seismic design and a few static loadings tests verify the actual nonlinear out-of-plane response of concrete walls. In a past study, an out-of-plane strength of outer concrete walls damaged by 2011 Tohoku Tsunami was evaluated based on the plastic hinge mechanism. In this study, the strength evaluation method is verified by the hydro static loading test on the concrete walls, and the out-of-plane strength are compared by the test between the bare concrete walls and walls reinforced with the polyester fiber sheets.

Polarization imaging for surface fiber orientation measurements of carbon fiber sheet molding compounds

The ability to measure the fiber orientation in fiber reinforced polymers plays a vital role in process and part design. Recently, it has been discovered that carbon fibers polarize light, providing an opportunity to detect the fiber orientation in carbon fiber-reinforced polymer parts. The Fraunhofer Institute for Integrated Circuits has developed a polarization camera system capable of measuring the polarization state of light reflected from objects in real-time. In this work, the camera system is used to measure the surface fiber orientation in carbon fiber reinforced Sheet Molding Compound semi-finished products at several stages of the processing chain. First, the fiber orientation of carbon fiber-reinforced Sheet Molding Compound semi-finished product is measured during continuous production, enabling real-time quality control and complete digitization of the material's fiber orientation information. Second, the measurement system is used to characterize static flat pressed carbon fiber reinforced Sheet Molding Compound specimens. In addition, the technique is widely applicable to many other carbon fiber based raw material forms (e.g. preforms, prepregs, tapes) and even composite parts.

Physics Informed Synthetic Image Generation for Deep Learning-Based Detection of Wrinkles and Folds

Abstract Deep learning-based image segmentation methods have showcased tremendous potential in defect detection applications for several manufacturing processes. Currently, majority of deep learning research for defect detection focuses on manufacturing processes where the defects have well-defined features and there is tremendous amount of image data available to learn such a data-dense model. This makes deep learning unsuitable for defect detection in high-mix low volume manufacturing applications where data are scarce and the features of defects are not well defined due to the nature of the process. Recently, there has been an increased impetus towards automation of high-performance manufacturing processes such as composite prepreg layup. Composite prepreg layup is high-mix low volume in nature and involves manipulation of a sheet-like material. In this work, we propose a deep learning framework to detect wrinkle-like defects during the composite prepreg layup process. Our work focuses on three main technological contributions: (1) generation of physics aware photo-realistic synthetic images with the combination of a thin-shell finite element-based sheet simulation and advanced graphics techniques for texture generation, (2) an open-source annotated dataset of 10,000 synthetic images and 1000 real process images of carbon fiber sheets with wrinkle-like defects, and (3) an efficient two-stage methodology for training the deep learning network on this hybrid dataset. Our method can achieve a mean average precision (mAP) of 0.98 on actual production data for detecting defects.

Investigation on Phoenix dactylifera/Calotropis procera Fibre-Reinforced Epoxy Hybrid Composites

This paper presents the investigations conducted on three types of fibre-reinforced epoxy-resin hybrid composites with different structures, manufactured using midrib long fibres of date palm (Phoenix dactylifera L.) and Calotropis procera fibres. The two types of fibres were formed into flat sheets, without adding other chemicals or resins, and employed as reinforcing layers in the structure of the multi-layered laminate composites. Three-layer and five-layer epoxy-reinforced laminates were manufactured from the sheets of date-palm fibres and Calotropis sheets bonded with laminar epoxy resin. Water resistance investigation and mechanical testing under tensile, bending and impact loads were conducted in the research in order to evaluate and compare the performance of the resulting composites. Emphasis was put on the effect of various factors, such as the type of reinforcement material and the number of plies in the laminate on the mechanical behavior of the composites. The interpretation of those results was supported by the stereo-microscopic investigation of the adhesion between the layers of the composites, and the vertical density profile (VDP), which showed the repartition of the density on the composite thickness depending on the layer material. The results of the mechanical performance of the composites showed lower values of tensile strength, tensile modulus of elasticity and impact resistance and an increase of water absorption (WA) and thickness swelling (TS) for the five-layer composites compared to the three-layer composites. Contrarily, the addition of Calotropis fibres improved the flexural strength and the flexural modulus of elasticity. The alkali treatment of the Calotropis fibres improved the mechanical performance of the composites compared to the ones made with untreated fibres, because of an apparent increase in cellulose content and free hydroxyl groups revealed by FTIR spectra.