Aramid Fiber Composites Research Articles

Permeability testing and mechanism analysis of aramid fiber hybrid fabrics

Aramid fiber composites have exceptional mechanical and insulating properties and are used in ultra-high-voltage power transmission. Fabric permeability is crucial for controlling composite defects. At present, the effective method to improve the permeability of aramid fibers is the hybridization of fiber fabrics. This study investigates permeability tests and impregnation mechanisms of aramid fiber fabric and its hybrid fabric. The permeability of the aramid fiber fabric and the hybrid fiber fabric was measured using a camera and a pressure sensor. The permeability of the fabric was analyzed by observing the structure, surface topography, dynamic contact angle, and surface free energy. The results show that the dynamic contact angle can be reduced and the surface free energy can be increased by hybridizing the fibers and the wettability of the fiber fabric is improved. Compared to an aramid fiber fabric, the in-plane permeability of aramid/glass fiber interlayer hybrid fabric increases by 36.19%, while the in-plane permeability of aramid/glass fiber intralayer hybrid fabric increases by 64.97%. The out-of-plane permeability of aramid/glass fiber interlayer hybrid fabric increases by 16.79%, while the in-plane permeability of aramid/glass fiber intralayer hybrid fabric increases by 30.1%. This study offers theoretical guidance for aramid fiber composite manufacturing and simulation input parameters.

Mechanical Properties of Aramid Fiber Fabrics and Composites Enhanced by Phthalic Anhydride Catalyzed with Anhydrous Aluminum Chloride

The surface modification of aramid fiber plain fabric (PPTA) was conducted through phthalic anhydride treatment and anhydrous aluminum chloride (AlCl3) catalysis, aiming to enhance the interfacial bonding strength between aramid fiber fabric and bisphenol A diglycidyl ether (DGEBA) resin. The surface morphologies and structures of PPTA fiber before and after modification were characterized using scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, and X-ray diffractometry. The mechanical properties of the PPTA/DGEBA composite were evaluated using a universal mechanical testing machine. The results demonstrate that when the concentration of phthalic anhydride is 0.3 mol/L, the tensile strength, bending strength and interlaminar shear strength of PPTA/DGEBA composites reach the maximum value, which are increased by 17.94%, 44.18%, and 15.94% compared with the unmodified sample, respectively. After a 0.5-h catalytic modification, the PPTA/DGEBA composites exhibited significantly enhanced tensile strength, bending strength, and interlaminar shear strength, achieving respective increments of 32.28%, 24.91%, and 29.10% compared to the modified samples without catalyst addition. Moreover, the overall mechanical properties of the aramid fiber fabrics and composites were substantially improved, which are more suitable for structural applications.

Composite Materials in Advancing Electric Aircraft Technologies

The transition towards electric aviation represents a significant stride in addressing the environmental impact of transportation, particularly concerning gas emissions. With the aviation sector identified as a substantial contributor to carbon emissions, the development of electric aircraft emerges as a crucial innovation towards achieving sustainable air travel. This paper explores the role of composite materials in the advancement of electric aircraft, focusing on their application in airframe construction, electrical systems integration, and the enhancement of propulsion systems. Composite materials, including carbon fiber-reinforced polymer (CFRP), glass fiber-reinforced polymer (GFRP), aramid fiber composite, and hybrid composites, offer superior strength, reduced weight, and high durability, making them ideal for electric aircraft design. Despite their advantages, challenges such as high manufacturing costs and recycling complexities persist. Through a comprehensive analysis, this study examines the potential of advanced manufacturing techniques and sustainable organic materials in overcoming these hurdles, paving the way for the widespread adoption of electric aircraft. The paper highlights the transformative impact of composite materials on electric aviation, addressing both the performance enhancements they facilitate and the obstacles to their broader application.

Preparation of a cyclotriphosphazene microsphere bearing a phosphaphenanthrene structure towards fire-safety and mechanical enhancement for epoxy and its aramid fiber composite

The mismatch of flame retardancy and mechanical properties is still a challenge for developing high-performance epoxy resin (EP) and its aramid fiber (AF) composite.

Reducing delamination risk with response surface methodology-supported drilling analysis for Nomex® aramid fiber composites

This article presents a comprehensive experimental investigation into the drilling behavior of Nomex®, a type of aramid fiber. The study specifically examines the impact of various cutting parameters and drill bit types on drilling outcomes. While Nomex® offers many advantages, difficult chip evacuation during drilling of aramid fiber composites can lead to surface defects and delamination. The research aims to explore how drilling parameters—such as spindle speed, feed rate—and four distinct drill bit types affect drilling performance. The analysis encompasses factors such as thrust force, torque, and surface roughness, studied under different drilling conditions and with various drill bit types. Moreover, the research assesses peeling and push-out delamination factors to gain insights into drill bit and coating characteristics. An examination of burr and chipping further enhances the comprehension of drilling performance. To determine the most effective drilling conditions, the study employs multi-response optimization. The optimal drilling performance is achieved with a combination of a 0.1 mm/rev feed rate, 1402.82 r/min spindle speed, and HSS-TiN drill type. This configuration successfully integrates responses, resulting in a composite desirability value of 0.95.

Aramid Fiber Composites for Sporting Equipment: Exploring Preparation Methods and Mechanical Properties

This study investigates the novel utilization of aramid fiber composite materials in sports equipment, elucidating their mechanical properties and development processes. Aramid fibers, despite their relatively brief 30-year existence in the materials realm, have emerged as pivotal elements in composite material research. Their exceptional traits, including high tensile strength, resistance to corrosion, impact resilience, pliancy, and effective thermal insulation, have rendered them pivotal in diverse applications, particularly in sports equipment. This research delves into the meticulous preparation methods of aramid fiber composites and comprehensively analyzes their mechanical attributes. Experimental findings ascertain a direct and proportional relationship between the tensile strength of these composites and the surface density of the fabric. Moreover, investigations into impact strength and wear rate, particularly at a 10% aramid fiber content, showcase optimal performance under varying temperature conditions. This study accentuates the immense potential of aramid composites in elevating the performance and durability of sports equipment, thereby paving the way for significant advancements in this domain.

A novel promotion strategy for flexible and compressive performance of Al2O3 felt via aramid fiber composite

As high-temperature-resistant inorganic fibers, Al2O3 fibers possess high-temperature resistance, high-temperature oxidation resistance, and chemical stability, and thus are suitable for applications such as high temperature catalysis and filtration. However, their shortcomings, such as high brittleness and high fracturability, limit their applications. In this study, a flexible Al2O3/aramid composite felt was prepared by introducing aramid fibers into Al2O3 fiber filaments, and the flexibility of the prepared composite felt was improved by using needle punching. The influence of the Al2O3/aramid doping ratio on the thermal insulation performance of the composite felt was explored. The findings showed that as the Al2O3/aramid doping ratio increased, the thermal insulation performance of the composite felt improved, whereas its thermal conductivity decreased. At room temperature of 25 °C and with an Al2O3/aramid doping ratio of 12:1, the thermal conductivity of the composite felt reached its minimum value of 0.0306 W m−1 K−1, while its compression and fracture moduli became 0.4 MPa and 21.5 GPa, respectively. The thermal-insulation mechanism of the composite felt was also explored in the study.

Synthesis of fractal crystallized organic microspheres together with constructing full covalent bonding at the interface to strengthen and toughen aramid fiber composites

Regulating the interface to simultaneously enhance the strength and toughness of aramid fiber composites remains a great challenge. Herein, a resilient, full covalent interface was constructed by introducing fractal crystallized organic microspheres into the interface of aramid fiber composites using the twice fluorination approach. Firstly, the aromatic polyamide with ether bonds was synthesized, and the fractal crystallized microspheres with a porous surface containing amino groups were prepared by thermally induced solution self-assembly. Subsequently, the twice fluorination method introduces C–F bonds to the surfaces of both fibers and microspheres, respectively. Then, the covalent bonds among fibers, microsphere, and resin were formed by the derivative reaction of C–F bonds. This interface boosts the interlaminar shear strength (ILSS) of composites by 100.5% to 36.7 MPa and the unnotched impact toughness of composites by 13.5%–1363 kJ/m2. Comparative analyses reveal the full covalent interface and the fractal structure of microspheres contribute 47.8% and 52.2% to the ILSS enhancement, respectively. In addition, the fractal structure of microspheres is the only factor for increased toughness. Finite element analysis reveals that the fractal crystallized microspheres combined with full covalent interface facilitate elastic stress transfer within the composites to enhance the performance of composites.

Hybridization effects on ballistic impact behavior of carbon/ aramid fiber reinforced hybrid composite

Fiber reinforced polymer and its hybrid composites are widely used in bulletproof production. The ballistic limit, failure mode and energy absorption of a hybrid fiber reinforced polymer target (HFRPT) composed of carbon fiber reinforced polymer (CFRP) and aramid fiber composite (AF) were studied in this paper. A finite element model was formulated to investigate the hybridization effect of layer thickness and stacking sequence on the ballistic behavior. A theoretical method was proposed to predict the ballistic limits of HFRPT, demonstrating an error percentage of less than 10% in most of the hybridization. Four typical failure modes including compression failure, tensile failure, shear plugging failure and tension shear coupling failure were observed in HFRPT, and the influence of hybridization on the alternations of failure modes was observed. Additionally, the effect of stacking sequences and layer thickness on energy absorption of HFRPT was examined. For the HFRPTs with a total thickness of 10 mm, the AF/CFRP hybridization proves to offer better ballistic impact resistance performance than the CFRP/AF hybridization. The HFRPT with a stacking sequence of 9 mm AF and 1 mm CFRP achieves a maximum ballistic limit of 420 m/s and the highest impact energy areal density ratio of 323 J/(g/cm2).

Continuous 3D Printing of Biomimetic Beetle Mandible Structure with Long Bundles of Aramid Fiber Composites.

Fiber-reinforced composites are an ideal high-performance composite material made from a combination of high-strength continuous fibers and a polymer matrix. Compared to short cut fibers, continuous long strand fibers can improve the mechanical properties of fiber composites more effectively. Herein, continuous aramid fiber-reinforced PLA filaments with fiber centering were prepared by modifying the outlet design of a desktop-grade thermoplastic single-screw melt extruder. Inspired by the cross-laminated structure of a beetle's mandible fibers, a biomimetic structure composite was printed, which demonstrates a significant influence on the mechanical properties. The G-code printing program was developed, and the microstructure of the fracture surface of the specimen was analyzed. The uniform and orderly arrangement of aramid fibers within the PLA resin-based 3D-printed specimen was found. Consequentially, the bionic composites exhibits a 12% increase in tensile strength and a 5% increase in impact toughness, confirming the feasibility of utilizing continuous 3D printing to manufacture long bundles of aramid fiber composite filaments for enhanced mechanical performances.

Review on Mechanical Characteristics of Kevlar Composites

Nowadays, industries are focusing on developing new materials which must have good durability, bio degradable and with ease of fabrication. For military application, aramid fiber is mostly preferred due to their high impact resistance property. If natural fiber is also combined with aramid fiber then industries can produce biodegradable material. Hence, this paper reviews aramid fiber (Kevlar) composites fabricated with natural fibers. In this paper, the mechanical characteristics of Kevlar composites and various combinations of natural with Kevlar composites have been discussed in detail

Enhanced Aramid/Al2O3 interfacial properties by PDDA modification for the preparation of composite insulating paper

To further improve the electrical insulation properties of meta-aramid paper, polydimethyldiallyl ammonium chloride (PDDA) was used for the modification of nano-Al2O3 in this work. The modified products were characterized by means of transmission electron microscopy, Fourier transform infrared spectrometer and liquid Zeta potential. The original and PDDA-modified nano-Al2O3 was doped into the aramid fiber composite, and the effects of PDDA and filler mass fraction on several properties such as electrical conductivity, breakdown strength and surface charge dissipation rate of insulating paper were studied. Finally, the interfacial properties of the composites were investigated using molecular dynamics. The results showed that PDDA was successfully coated on the surface of nano-Al2O3, and its surface potential was changed from negative to positive, which could improve the interface characteristics between filler and matrix and enhance the dielectric strength of aramid paper. Besides, saturation effect of PDDA modification was observed, and when the amount of PDDA was 10% and the content of modified nano-Al2O3 was 3%, the breakdown strength of aramid paper was increased by 20%, and the volume conductivity was decreased by 68%. The simulation result revealed that PDDA could improve the insulation performance of aramid paper by reducing the interfacial binding energy between aramid and filler.

Interfacial Properties of Aramid Fiber Composites Reinforced with SiO2-Coated ZnO Nanoparticles

Interfacial Properties of Aramid Fiber Composites Reinforced with SiO2-Coated ZnO Nanoparticles

Improvement of the Mechanical Properties by Surface Modification of ZnCl2 and Polydopamine in Aramid Fiber Composites

Although aramid fiber has the advantage of excellent chemical and mechanical properties, the performance of the composites may be reduced due to the low interfacial adhesion between the fabric and the matrix. The surface of the aramid fiber was modified to improve the interfacial properties. The surface of the aramid fibers was treated with ZnCl2 and polydopamine. After the pretreated fabrics were made into a composite material by the vacuum-assisted resin transfer molding (VARTM) process, their mechanical performance was investigated. The highest impact energy was shown in the concentration of 6 wt% ZnCl2 and 1.5 g/L polydopamine, which is 20% better than that of the untreated material. In the bending strength, the condition of 1.5 g/L polydopamine resulted in the highest value and increased by 13% compared to the untreated material. The hybrid surface treatment of ZnCl2 and polydopamine did not significantly affect the tensile strength.

The translaminar fracture toughness of high-performance polymer fibre composites and their carbon fibre hybrids

The translaminar fracture toughness is a key property that governs the damage tolerance and notch sensitivity of fibre-reinforced composites. Compact tension tests were performed to investigate the translaminar fracture toughness of composites reinforced with three types of high-performance polymer fibres: polyarylate (PAR), polybenzobisoxazole (PBO) and aramid fibre. A carbon fibre composite was used as the reference system. The propagation translaminar fracture toughnesses of the PAR and PBO fibre composites were 492 kJ/m2 and 547 kJ/m2, respectively. These are among the highest translaminar fracture toughness values recorded in the literature. It was hypothesized that the fibrillation of the fibres upon failure was an important energy dissipating mechanism alongside pull-outs that were much longer than for carbon fibre. Replacing a small strip of a carbon fibre ply by a strip of PAR or PBO fibres successfully reinforced the material by locally arresting crack growth. By contrast, the performance of the aramid fibre composites and their hybrids with carbon fibre was lacklustre. The results presented in this work can be used to further improve the safety of composite parts by optimising the design for damage tolerance while also reducing the weight of the parts.

Mechanical and tribological behaviour of PA6 and short aramid fiber composites

This paper presents the results of mechanical and tribological characteristics for two composites: PA6 as matrix and 5% aramid whiskers as additive material and PA6 + 10% aramid whiskers, comparing them to those made of PA6 (polyamide 6). To improve the mechanical and thermal properties of polyamide (PA6), the composites were prepared via the Brabender lab mixer and mould forming under given pressure and temperature conditions. Test specimens made of pure PA6 and PA6 mixed with 5 wt.% and 10 wt.% aramid whiskers were subjected to mechanical tests (three-point bending and impact), thermo–mechanical test (HDT - heat deflection temperature), tribological test (block-on-ring) and analyzed from morpho-structural point of view. Compared to the PA6 samples, the mass concentrations of aramid whiskers improved the HDT deflection temperature values. In the case of samples with 5% aramid whiskers, the absorbed energy increased by 13% and for those with 10% aramid whiskers they increased by 30%. Aramid whiskers-doped materials performed much better on severe tribological testing as compared to PA6 samples. Increasing the deflection temperature, also improved their resistance from a tribological point of view.

Influence of the addition of graphene nanoplatelets on the ballistic properties of HDPE/aramid multi-laminar composites

ABSTRACT The application of aramid fiber composites for ballistic purposes has increased in recent years. The addition of graphene in a polymeric matrix could boost the energy absorption and the ballistic protection of these composites. This study aims to investigate the performance of aramid fabric multi-laminar panels with high-density polyethylene (HDPE) films containing graphene nanoplatelets (GNP). Mechanical, dynamic-mechanical (DMA), ballistic impact, and split Hopkinson pressure testing were conducted. All composites obtained ballistic protection level III-A, with HDPE-0.5% GNP and HDPE-1% GNP obtaining the lowest subsequent deformations. HDPE-0.5% GNP showed the highest energy dissipation in DMA testing, corroborating the ballistic results.

Failure analysis of composite-to-titanium single lap adhesive joints subjected to tensile loading

Similar (composite, titanium) and dissimilar (composite-to-titanium) single lap adhesive joints were made of the titanium alloy and aramid fiber composite. The joint surface strain and failure modes under tensile load were characterized using a digital image correlation (DIC) system, strain acquisition system and optical microscope (OM). The strain distribution and failure morphology of similar and dissimilar joints were compared to analyzing joints’ bonding performance and failure characteristics. The strain evolution in the dissimilar joint was quantified to figure out failure process. The results showed that the lateral offset and deformation of dissimilar joints are higher than those of titanium and composite joints, which causes dissimilar joints to have lower bonding strength. Shearing and peeling stress concentrate at the upper end of composite, and the joint firstly fails from here. After starting failure, a high tensile strain region appears on the composite surface, and a high bending strain region appears on the surface of titanium. Both regions move along the debonding direction. Tensile and bending stress of adherend at the edge of remaining bonded area further rise, resulting in eventual failure of the joint. The joint appears in sequence with the failure of composite delamination and the interfacial failure between the titanium and adhesive.

A multiscale model for the prediction of ballistic performance of fiber-reinforced composites

This study investigates in-depth the effects of dimensions and properties of constituents at microscale on the impact performance of macroscopic fiber-reinforced laminates. A numerical algorithm incorporating the dynamic shear-lag model is developed. Applying the numerical dynamic shear-lag model to three typical impulse forms, a common linear relationship between the optimal dimensionless viscosity and impulse duration emerges. This linear relationship can guide the selection of matrix materials to optimize the energy dissipation. Furthermore, a new multiscale model is established by extending the dynamic shear-lag model to the laminate scale to take into account the contribution to the energy absorption from the matrix. This multiscale model successfully captures the effect of matrix properties on the ballistic limits of aramid fiber and carbon fiber composites from previous experiments by two independent groups.

Effect of root-like mechanical-interlocking interface in polypropylene /aramid fiber composites from experimental to numerical study

Poor interfacial interaction of fiber-reinforced polymer composites is a crucial impediment to expand the practical application. Here, we reported a facile strategy to construct a mechanically-interlocking interface in polypropylene (PP)/aramid fiber (AF) composite by utilizing the interfacial diffusion and epitaxial growth of amide-based self-assembling compounds (NA) on the surface of the reinforcing fiber driven by the polarity differences between the three components. The results showed that when NA was introduced to PP/AF composite, NA preferred to aggregate and immobilize on the AF surface by directed diffusion and self-assembly due to strong hydrogen bonding and similar polarity between AF and NA. Subsequently, the NA assembly epitaxially crystallized into branched fibers, forming root-like reinforcing fibers anchored on the interface and then inducing the formation of transcrystalline layers of PP. The branched fibers and transcrystalline layers imposed the mechanically-interlocking effect on the PP/AF interface to greatly enhance the interfacial interaction, with a remarkable increase of 48.1% in interfacial shear strength compared to the conventional PP/AF composite featuring smooth interface. To verify the mechanical enhancement effect, tentative impact and tensile tests were adopted and results presented that impact strength of PP/AF/NA composite with finely designed interfaces was improved by 22.0% in comparison with conventional PP/AF materials. Finally, the load-transferring mechanism from polymer to reinforcing fiber and the strengthening effect of the mechanical-interlocking interface were revealed by numerical study using the finite element method to pave the way of production of high-performance filler-reinforced composites.