Aramid Fiber Surface Research Articles

Tough, antimicrobial, recyclable hydrogel with tree-trunk-inspired core‐sheath structure for efficient all-day desalination

Solar-driven interfacial evaporation, an economically friendly freshwater harvesting technology, faces the challenge of achieving efficient all-day desalination. Inspired by the core‐sheath structure of tree trunks, herein, a hydrogel evaporator features internal vertical lamellar sodium alginate (SA) pores supported by aramid fiber (AF) networks and surface covered with a dense layer of copper sulfide (CuS) and was fabricated through freeze-drying-cycling alternating immersion method. The internal vertical SA lamellar structure endows the hydrogel with strong water transport capability, while the high photothermal conversion ability of the surface CuS layer enables rapid water evaporation. Therefore, as 2D evaporators, the evaporation rate in highly concentrated salt solutions (15 wt%) is up to 2.07 kg m-2 h-1 under 1.0 sun. As 3D evaporators, efficient evaporation is achieved throughout the day by compensating evaporation at the sides and top. Under the irradiation of 0.2 and 0.8 suns outdoors, the evaporation rate of the 3D evaporator can reach 7.47 kg m-2 h-1 and 12.60 kg m-2 h-1, respectively, and its total evaporation is 4.72 times higher than that of the 2D evaporator. Notably, the hydrogel evaporator has excellent anti-salt properties, antimicrobial properties, and recyclability. This work provides valuable guidance for designing and developing practical hydrogel evaporators.

Nacre-inspired composite papers with enhanced mechanical and electrical insulating properties: Assembly of aramid papers with aramid nanofibers and basalt nanosheets

Aramid papers (AP), made of aramid fibers, demonstrate superiority in electrical insulation applications. Unfortunately, the strength and electrical insulating properties of AP remain suboptimal, primarily due to the smooth surface and chemical inertness of aramid fibers. Herein, AP are modified via the nacre-mimetic structure composed of aramid nanofibers (ANF) and carbonylated basalt nanosheets (CBSNs). This is achieved by impregnating AP into an ANF-CBSNs (A-C) suspension containing a 3D ANF framework as the matrix and 2D CBSNs as fillers. The resultant biomimetic composite papers (AP/A-C composite papers) exhibit a layered “brick-and-mortar” structure, demonstrating superior mechanical and electrical insulating properties. Notably, the tensile strength and breakdown strength of AP/A-C5 composite papers reach 39.69 MPa and 22.04 kV mm−1, respectively, representing a 155 % and 85 % increase compared to those of the control AP. These impressive properties are accompanied with excellent volume resistivity, exceptional dielectric properties, impressive folding endurance, outstanding heat insulation, and remarkable flame retardance. The nacre-inspired strategy offers an effective approach for producing highly promising electrical insulating papers for advanced electrical equipment.

Green, simple, and rapid construction of coating on aramid fiber surfaces and their effects on the mechanical properties of aramid fiber/rubber composite interfaces

First, the surface of aramid fibers (AF) was etched using plasma to enhance the roughness of the AF. The coating was then formed on the surface of the AF by solution dip-coating using a polymerizable deep eutectic solvent (PDES) and in-situ UV cured for 10 s. The study examined the impact of varying etching times on the interfacial properties between AF and natural rubber (NR). The atomic force microscopy images showed that the surface roughness gradually increased with the increase of etching time, and the interphase width gradually increased. A modulus interfacial layer with a platform role was established between high-modulus aramid fibers and low-modulus rubber. And when the etching time was 4 s/cm, the H pull-out force increased by 193.51% compared to the original AF and reached 18.08 N of the maximum strength. Comprehensively comparing the single fiber tensile strength, composite tensile strength and composite fatigue resistance, the AF-reinforced NR composites can be optimized when the treatment time is 3 s/cm. In sum up, this method of constructing a coating on the AF surface by etching first will lead to a great improvement in the interfacial properties between AF and NR, this method enables simple, green and continuous construction of coating on AF surfaces, making them have great application prospects in the field of aviation tires.

Interaction mechanisms between fibers and bubbles during foam forming

It is critical to understand the interaction mechanism of fiber-bubble before the foam-forming technique is used to disperse the long fiber and tailor the material microporous structure. Herein, the adhesion behavior of ionic and nonionic surfactants with different concentrations on five fibers was investigated, and the effect of electrostatic force and adhesion driving force on the interaction between fibers and bubbles was analyzed. In addition, the fiber dispersion mechanisms and the response mechanism of the fiber orientation and tensile strength of foam-formed paper on the interaction strength between fiber and bubble were clarified. The results show that the adhesion ability between hydrophobic fibers with weak surface polarity and cationic and amphoteric surfactants is more obvious. Though electrostatic repulsion weakens the interaction strength of fibers with anionic surfactants, the adhesion ability can exist when the adhesion driving force is larger than 6.6 mN/m. Furthermore, the bridge effect between ethoxylated surfactant headgroups with the acylamino on the aramid fiber surface also propels the adhesion behavior of bubble-fiber. The fiber dispersion mechanisms were proposed based on the adhesion effect of the fiber-bubble, electrostatic elimination, and high-viscosity (≥95 mPa∙s) properties of the “foam-fiber” slurry. Eventually, under the gradually decreased interaction strength between fibers and bubbles, the fiber orientation in the Z direction of foam-formed NBSKP fiber paper turned from −20°-20° to −60°-40°, and the tensile strength decreased from 693 KPa to 537 KPa. This work has implications for improving the long fiber dispersion and regulating the structure of foam-formed fiber composites.

A promising method for promoting interfacial adhesion of aramid/rubber composite using atmospheric pressure plasma surface modification

AbstractToday, aramid fibers are well known as a high‐performance and ideal material for reinforcement purposes in rubber product manufacturing including hoses, tires, cables, and conveyors composites. However, surface modification of aramid fiber is necessary to solve poor interfacial adhesion between aramid fibers and the rubber matrix. Accordingly, in the present study, the effect of the surface modification of aramid fibers using atmospheric pressure plasma treatment with different precursors on adhesion to the rubber matrix was investigated. For that, the plasma coating was conducted using argon as the main working gas, and toluene, acetonitrile, tetraethyl orthosilicate (TEOS), and hexamethyldisiloxane (HMDSO) as liquid precursors. The physical–chemical characterization of the layer confirmed the successful deposition of amorphous carbon, amorphous nitride‐carbon, SiO2, and Polydimethylsiloxane (PDMS)‐like coating layers on the surface of aramid fibers by using toluene, acetonitrile, TEOS, and HMDSO as precursors, respectively. Overall, the result showed that the plasma surface modifications with acetonitrile precursor leads to the increase in interfacial adhesion of aramid/rubber composite, while retaining the tensile strength, and flame resistance properties of aramid as original fibers. Notably, the results of this study confirm the potential use of atmospheric pressure plasma for surface modification of aramid yarn to produce functional aramid for use in rubber composites.Highlights The plasma‐coated aramid using HMDSO, TEOS, toluene, and acetonitrile precursors was prepared; and its effect on the tensile properties of aramid fiber as well as interfacial adhesion between aramid/rubber composite was investigated. The positive effect of atmospheric pressure plasma coating using HMDSO precursor on the tensile properties of aramid fiber was revealed. The positive effect of atmospheric pressure plasma coating using toluene and acetonitrile on the interfacial adhesion between aramid/rubber composite was revealed. The positive effect of atmospheric pressure plasma coating using TEOS precursor on the flam resistance property of aramid fiber was revealed. This study provides valuable insights into the effect of the different plasma‐coated organosilicon and hydrocarbon precursors on the interfacial adhesion between aramid/rubber composite.

A top-down and in situ strategy for intrinsic acicular nanostructure enhanced ultradurable superhydrophobic and anti-icing aramid fabric

Essential requirements of protective clothing with multi-scenario practicability deserve intensive attention. Aramid fabric is widely used to protect industrial and outdoor workers operating under various hazardous conditions but is susceptible to fouling, subzero cold water and icing, resulting in severely deteriorated protective properties. However, the chemical inertness of aramid fabrics limits their further functionalization. This issue is addressed herein by developing a novel top-down strategy to construct an intrinsic densely packed acicular nanostructure on the surface of aramid fiber through the proton donor-assisted deprotonation-induced roughening (PAIR) method. The PAIR treatment consists of extracting hydrogen protons from the amide moiety and controllably dissociating the outer shell of the aramid fibers without destroying its hard-core structure. Such a “rough-surface-on-intact-core” texture endows the fabric with greatly enhanced water repellency, anti-icing and anti-fouling properties without sacrificing its impressive mechanical properties, moisture permeability and flame retardancy. Remarkably, the treated fabric can load 37 times its own weight in water, presenting an increased buoyancy and demonstrates an icing delay time of 1920 s, which is 1150 % that of a pristine aramid fabric. Featuring the easy processability, high endurance and multiple functions, the fabric is promising for applications in personal protective equipment and advanced functional textiles with multiple tasks under harsh weather events.

In situ creation of aramid fiber surface coating with polymerizable deep eutectic solvents and their interfacial bonding properties with rubber

AbstractThe coating was created on the surface of aramid fibers (AFs) by solution dip‐coating and in situ UV curable method, using a polymerizable deep eutectic solvent (PDES), dissolved poly(ethylene imine), and poly(ethylene glycol) diacrylate (PEGDA). Fourier transform infrared spectroscopy and thermogravimetry confirmed the successful construction of the coating on the AF surface, which accounted for 12%–17% of the total fiber mass. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) images revealed a 2 μm increase in fiber diameter and a maximum fiber surface average roughness (Ra) of 263.7 nm when the polyethyleneimine content was 0.5% (AF‐PDES‐0.5). Based on these results, H pull‐out samples of fiber/rubber composites were fabricated. The results indicated that the H pull‐out force of AF‐PDES‐0.5 samples increased by 109.74% than that of untreated fiber, and reached 12.92 N of the maximum strength. In summary, the method is simple, rapid, non‐polluting, capable of continuous, and intelligent construction of coatings on the surface of AF. Thus, making it highly promising for application in the field of aviation tires.Highlights Using PDES, green, and low‐carbon preparation processes. Solution dip‐coating and UV reaction for improved reaction speed and workability. Quantitative of interface thickness and modulus using EDS and AFM.

Improved dielectric and mechanical properties of aramid fiber reinforced epoxy resin composites by polyethyleneimine grafting

In this paper, aramid fiber surface is modified by polyethylenimine (PEI) grafting with abundant -NH2 active groups after plasma surface activation treatment. Various aramid fiber reinforced epoxy resin composites (AFRC) are prepared. The effects of PEI grafting on the dielectric and mechanical properties of AFRC are studied. Obtained results show that PEI is successfully grafted onto aramid fiber surface as evidenced by x-ray photoelectron spectroscopy results, and effectively improves the interfacial properties between aramid fiber and epoxy resin. The dielectric properties, including DC conductivity, dielectric constant, and integration charge Q(t) of the composites are improved after optimized modification parameters, and the breakdown strength is increased by up to 23%. These are attributed to the decrease in interfacial polarization and the increase in interfacial bonding strength. Furthermore, the interfacial shear strength of AFRC is increased from 29.5 MPa to 63.7 MPa, which further verifies the improvement of interfacial performance. This paper provides a way to improve the dielectric and mechanical properties of AFRC, which is of great significance for its application in high voltage power equipment.

Protect aramid materials from UV‐induced damage by ANF and ANF/light stabilizer composites

AbstractAramid materials have been applied in many important civil and military fields. But a major drawback to aramid materials is the susceptibility to UV‐induced damage. In this work, aramid nanofibers (ANFs) and ANF/nano‐ZnO composites were used to protect aramid materials from UV‐induced damage. ANF protective layer was created on the surface of aramid fibers, and the ANF‐coated aramid fibers could be further prepared to aramid paper. Moreover, ANF/nano‐ZnO composites were synthesized and used for stronger UV‐blocking ability. ANFs provided effective protection to aramid material. The properties after UV exposure (about 9.3 years in the natural environment) were largely improved: ANFs improved the retention rate of strength by 17.96% for aramid fibers and by 16.93% for aramid paper. ANFs also showed synergistic effect with UV‐absorbing inorganic nanoparticles. After UV exposure, the tensile strength of aramid paper with ANF/nano‐ZnO composites was even higher than the initial value (121.55%), and the retention rate of strength was 2.43 times higher than the original aramid paper.

Effects of Air Plasma Modification on Aramid Fiber Surface and Its Composite Interface and Mechanical Properties.

In order to improve the interface and mechanical properties of aramid fiber (AF)-reinforced epoxy resin (EP) composites (AF/EPs), the surface modification of AF was carried out with atmospheric pressure air plasma, and the effects of plasma treatment time and discharge power on the AF surface and the interface and mechanical properties of AF/EPs were investigated. The results show that, when plasma treatment time was 10 min and discharge power was 400 W, AF showed the best modification effect. Compared to the unmodified material, the total content of active groups on the surface of AF increased by 82.4%; the contact angle between AF and EP decreased by 20%; the interfacial energy and work of adhesion increased by 77.1% and 19.1%, respectively; the loss of AF monofilament tensile strength was controlled at only 8.6%; and the interlaminar shear strength and tensile strength of AF/EPs increased by 45.5% and 10.4%, respectively. The improvement in AF/EP interfacial and mechanical properties is due to the introduction of more active groups on the AF surface with suitable plasma processing parameters, which strengthens the chemical bonding between the AF and EP matrix. At the same time, plasma treatment effectively increases the surface roughness of AF, and the mechanical meshing effect between the AF and EP matrix is improved. The synergistic effect of chemical bonding and mechanical meshing improves the wettability and interfacial bonding strength between the AF and EP matrix, which enables the load to be transferred from the resin to the fiber more efficiently, thereby improving the mechanical properties of the AF/EP.

Secondary silane grafting on aramid fibers improves the interfacial bonding performance in textile composite materials

To improve the chemical and physical surface features of aramid fibers and the bonding quality at the interface, carbon nanotubes, dopamine and silane coupling reagent KH560 were used to modify the surface of aramid fibers. The fiber surface was characterized by FTIR, XPS, SEM and AFM. The single-fiber specific strength, surface roughness, wettability and interfacial shear strength of the modified fiber were quantified. Finally, the uniaxial tensile behaviour of the textile composite laminate with the modified fibers was tested. The experimental results show that: after the grafting of silane coupling reagent as a second modification step, the amount of oxygen-containing groups on the surface of aramid fibers, and the surface roughness, and the ability to impregnate resin are further improved. The single-fiber specific strength, the interfacial shear strength by fiber pull-out tests, and the tensile strength of the laminate are increased by 21.62%, 73.57%, and 51.60%, respectively. This work demonstrates a general surface modification strategy working for diverse types of fibers, synthetic or natural. The present findings help to develop a broad range of high-performance textile composites to address long-term challenges in structural engineering.

Aramid Fiber Surface Area Impact on Elastomer Crack Growth

Aramid Fiber Surface Area Impact on Elastomer Crack Growth

Surface construction of ANF/CNT onto aramid fibers to enhance interfacial adhesion and provide real-time monitoring of deformation

To solve the poor interface between aramid fiber and rubber, this paper studies a method of constructing nanostructures on the fiber surface. First, functional groups such as hydroxyl and amino groups were introduced onto aramid fiber through the Michael addition of tannic acid and polyethyleneimine. Then, the modified aramid fiber was impregnated in the aramid nanofiber/carbon nanotube aqueous dispersion to prepare a surface-coated fiber. The fibers and surface nanostructures were characterized by scanning electron microscopy, transmission electron microscope, Raman spectroscopy, X-ray photoelectron spectroscopy, thermalgravimetric analysis, and H pull-out tests in detail. The results show that the H pull-out force of the coated fiber is increased by 126.4% compared with the original aramid fiber, which is due to the good mechanical interlocking at the interface of the composites. In addition, carbon nanotubes could form a conductive path through mutual entanglement and overlap on the surface of aramid fiber, which also gives the function of real-time monitoring of deformation of the composites.

Impact of the plasma flow of a low-pressure high-frequency capacitive discharge on the adhesive and physical and mechanical characteristics of aramid and carbon fibers

The changes in the adhesive and physico-mechanical characteristics of aramid and carbon fibers treated with plasma of a highfrequency capacitive gas discharge of reduced pressure are considered. An increase of ~ 30% in the wettability of the surface of aramid and carbon fibers is shown. It was found that the strength of plastics made on the basis of aramid and carbon fibers treated with a plasma flow increases by ~ 26%.

Dopamine-modified aramid fibers reinforced epoxidized natural rubber nanocomposites

Via the amino activity of dopamine, poly(dopamine) (PDA) is covered on the surface of aramid fibers (AFs) by a simple dip coating method. Benzoyl aniline is used as a model compound of AF to disclose the action between dopamine and AF. PDA does not produce a chemical bond between coating and AFs. The self-polymerized PDA coating and following epoxidized natural rubber (ENR) grafting on the AF surface contribute to the improved surface roughness and surface activity. The interface strength is increased by 37% with the concentration of dopamine at 2 g/L and ENR at 40 g/L.

Characterization of fiber/matrix interfacial bonding strength of chemically grafted aramid fiber surface with epoxy resin composites

AbstractThis research work focuses to improve the interfacial adhesion in aramid/epoxy composites by various chemical treatments of aramid fiber surface. The effect of chemical grafting on the fiber surface was studied using X‐ray diffractometer and field emission scanning electron microscopy. In addition, short beam and microbond tests were carried out to evaluate the interlaminar shear strength (ILSS) and interfacial shear strength (IFSS) respectively. Moreover, the single fiber tensile strength and fracture toughness of treated and untreated (NT) aramid fibers were computed. The results reveal that the ILSS and IFSS of erpichlorohydrin with phosphoric acid pre‐treated (TE‐P) fibers having 140.92% and 66.89% higher than untreated (NT) fibers. Consequently, the single fiber tensile strength of surface modified aramid filament is 31.22% higher than the untreated (NT) filament. Later, the Weibull model was developed to predict the single fiber tensile strength. Significantly, the result shows that the interfacial fracture toughness of TE‐P treated fibers was improved by 170.10% as compared with untreated (NT) fibers. Finally, fractographic analysis was employed to validate the improvement of interfacial adhesion properties in aramid/epoxy composites.

Laser-induced graphenization of textile yarn for wearable electronics application

The present paper deals with the selective laser writing of textile yarns in order to induce a conductive path useful for smart textiles application. The incident power of the laser induces a conversion of an aramid fiber surface into graphene-based conductive material with tunable electrical properties depending on the laser writing parameters. The physical-chemical properties of the resulting smart yarns have been intensively characterized by electron microscopy, Raman spectroscopy, electrical and mechanical investigations. The results confirm the few-layer graphene fingerprint of the written paths onto the textile yarn with suitable properties for their application into electronic textiles. Indeed, a yarn-shape strain sensor with excellent performance has been developed and characterized to demonstrate the potential application of the proposed technology to the wearable electronic field.

Nondestructive Grafting of ZnO on the Surface of Aramid Fibers Followed by Silane Grafting to Improve its Interfacial Adhesion Property with Rubber

Nondestructive Grafting of ZnO on the Surface of Aramid Fibers Followed by Silane Grafting to Improve its Interfacial Adhesion Property with Rubber

Study on the modified fiber with nacre layer structure based on bionic coating and molybdenum disulfide co‐construction incorporated asphalt

AbstractA green and efficient two‐step method was used to modify the surface of aramid fiber with a double shell structure by compounding MoS2 with dopamine and tannic acid to develop nacre fiber with enhanced interfacial effect, which was in turn applied to prepare nacre fiber incorporated modified asphalt. The nacre fiber and its incorporated modified asphalt were characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), fluorescence microscopy (FM), and dynamic shear rheometer (DSR). FTIR results indicated that the nacre fiber was highly dispersed in the matrix asphalt while it was highly thermally stable (THRI of 207.4°C) as confirmed by thermogravimetric analysis. FM and SEM analyses confirmed that the nacre fiber formed a uniformly dispersed and well‐developed three‐dimensional network structure in the matrix asphalt, which endorsed the nacre fiber modified asphalt with enhanced mechanical and viscoelastic properties as confirmed by DSR tests.

Surface Coating of Aramid Fiber by a Graphene/Aramid Nanofiber Hybrid Material to Enhance Interfacial Adhesion with Rubber Matrix

A novel method of constructing nanostructures on the surface of aramid fiber (AF) was demonstrated in this article. Through the π–π* interaction between the aramid nanofiber (ANF) and graphene (G),...