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Reverse osmosis membranes have been predominantly made from aromatic polyamide composite thin-films, although significant research efforts have been dedicated to discovering new materials and synthesis technologies to enhance the water–salt selectivity of membranes in the past decades. The lack of significant breakthroughs is partly attributed to the limited comprehensive understanding of the relationships between membrane features and their performance. Insights into the intrinsic features of reverse osmosis (RO) membranes based on metadata were obtained using explainable artificial intelligence to understand the relationships and unify the research efforts. The features related to the chemistry, membrane structure, modification methods, and membrane performance of RO membranes were derived from the dataset of more than 1000 RO membranes. Seven machine learning (ML) models were constructed to evaluate the membrane performances, and their applicability for the tasks was assessed using the metadata. The contribution of the features to RO performance was analyzed, and the ranking of their importance was revealed. This work holds promise for metadata analysis, evaluating the RO membrane against the state of the art and developing an inverse design strategy for the discovery of high-performance RO membranes. [ABSTRACT FROM AUTHOR]

Divanillic acid (DVA)-based aromatic polyamides (PAs) consisting of DVA with linear (methyl, butyl, hexyl, and octyl groups) or branched (isopropyl and isobutyl groups) side chains and 4,4'-methyldianillin were synthesized as high-performance and ultra-high-performance biomass plastics. The DVA PAs were amorphous with high thermal stability (decomposition temperature of ca. 380 °C). The glass transition temperature (Tg) of the DVA PAs depended on the side-chain composition in a linear manner, indicating the PA main chain possessed a random structure. The polymers were pressed to form melt-pressed films. The DVA PAs with a higher content of shorter side chains exhibited both higher Tg and tensile strength than those of polymers with a lower content of shorter side chains. The PAs exhibited Tg in the range of ca. 150–253 °C. The branched PA with isopropyl side chains exhibited the highest Tg of 253 °C and highest tensile strength of 63 MPa among the DVA PAs. The PAs with isopropyl side chains and some linear side chains (methyl/hexyl combination) exhibited high tensile strength of approximately 60–70 MPa; however, their Tg varied from 170 to 253 °C. The branched PA exhibited the highest Tg, tensile strength, and Young's modulus of the polymers. The thermal stability and mechanical properties of the PAs were tuned by their side-chain structure and composition. [ABSTRACT FROM AUTHOR]

In this study, an aluminum heating block with two inlets (for the Polylactic acid (PLA) filament and the continuous aramid fiber) was produced and placed onto an extruder, and continuous-aramid-fiber-reinforced PLA composites were fabricated by using the nozzle impregnation method. Layer height values of 0.4 mm, 0.6 mm, and 0.8 mm and hatch spacing values of 0.6 mm, 0.8 mm, and 1.0 mm were used for the investigation of the processing parameters on the properties of composites by differentiating the reinforcement volume fraction. Additionally, atmospheric plasma treatment was used for the surface modification of the reinforcement fiber. The properties of composites reinforced by using surface-modified fibers were also investigated in order to reveal the efficacy of the atmospheric plasma treatment on the properties of composites. The effect of the atmospheric plasma treatment on the fiber properties was investigated by using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). Continuous-aramid-fiber-reinforced PLA composites were characterized mechanically by fiber pull-out, tensile, and flexural testing. The fracture surfaces of composites were analyzed by using SEM. The combination of a reduced layer height and a narrower hatch spacing yielded the best mechanical performance, with a tensile strength of 410.25 MPa achieved at a 0.6 mm layer height and a 0.4 mm hatch spacing. This combination minimizes void formation, enhances fiber alignment, and strengthens interlayer adhesion, leading to superior mechanical properties. The FTIR and XPS results showed that atmospheric plasma modification can enhance the interfacial bonding strength by improving the surface morphology and increasing the content of polar groups on the fiber surface. By combining optimized manufacturing conditions with the atmospheric plasma treatment, the mechanical performance of continuous-aramid-fiber-reinforced PLA composites was enhanced. [ABSTRACT FROM AUTHOR]

The present study aims to evaluate thin plate-injected polypropylene (PP) composites containing short aramid fibers (AF) and graphene nanoplatelets (GNPs). The aramid fibers were manually cut to a length of 10 mm and added to the polypropylene matrix at a concentration of 10 wt.%. Additionally, GNPs were incorporated at concentrations of 0.1, 0.25, and 0.5 wt.%. Maleic anhydride grafted polypropylene (MAPP) was used at a concentration of 2 wt.% to improve the adhesion and compatibility between the polymer matrix and the fillers. Thermal analyses, tensile and flexural tests, and dynamic mechanical thermal analysis were performed, followed by statistical analysis using ANOVA and Tukey's test. The composites demonstrated significant improvements in storage and loss moduli compared to neat polypropylene. With the addition of AF and GNPs, tensile strength increased to 46.8 MPa, which represents a 265% enhancement compared to PP. Similarly, flexural strength reached 62.4 MPa, significantly higher than the 36.73 MPa for PP, particularly for the composite containing AF and 0.25 wt.% GNPs. The results presented in this study highlight the synergistic effect of aramid fibers and GNPs on PP. These improvements make the proposed composites highly promising for a range of applications, including ballistic interlayered aramid/thin-plate laminates. [ABSTRACT FROM AUTHOR]

This study addresses the issue of low surface energy of aramid fibers and their fabrics and aims to enhance their mechanical properties including tensile strength and impact resistance. Using the hollow spindle spinning method, aramid fiber bundles are employed as the core yarns with varying twist levels and nylon fibers are used as the wrapping yarns to create the nylon/aramid-wrapped yarns, which are then woven into the nylon/aramid fabrics. The investigation focuses on the effect of core yarn twist levels on the mechanical properties of the yarns and fabrics. Experimental results reveal that applying an appropriate core yarn twist can significantly improve the mechanical properties of the yarns and fabrics. Specifically, with the optimized the core yarn twist of 80 turns per meter (tpm) the tensile and hook strengths of the wrapped yarns reach 3.3 GPa and 1.2 N/Tex, respectively which are about 20.6% and 21.7% increase as compared to the untwisted yarns. Similarly, the plain-woven fabric consisting of the 80 tpm yarns achieves a tensile strength of 2577.9 N/cm, a pull-out force of 160.2 N, and an absorbed energy per unit volume of 436.5 KJ/m3 which are about 20.0%, 31.4% and 30.1% improvement, respectively as compared to the fabrics with the untwisted yarns. Additionally, the optimized fabric presents a 28.4% increase in the energy absorption efficiency and significant enhancement in abrasion resistance. These findings offer valuable insights for the potential applications of the nylon/aramid-wrapped yarns for developing personal protective fabrics and products. [ABSTRACT FROM AUTHOR]

This research aims to analyze the elastic behavior of intralayer hybrid composites that consist of an epoxy matrix and aramid-carbon reinforcement. The contrast in stiffness between the aramid and carbon fibers leads to highly heterogeneous distributions of strains at the mesoscopic level. Therefore, our main objective is to investigate the strain fields at the mesoscopic level experimentally and numerically. We performed measurements using the digital image correlation (DIC) method, while the numerical model was built using a two-scale approach involving the finite element method (FEM). Good agreement was observed between the experimental and numerical results. [ABSTRACT FROM AUTHOR]

The field of composite materials is rapidly expanding due to advancements in materials and manufacturing, driven by environmental concerns for reduced weight, increased energy efficiency, and recyclability. While thermoset composites are crucial, thermoplastics are gaining popularity for their sustainability and manufacturing advantages. They offer quicker processing, easier production, and recyclability, aligning with sustainability goals. While carbon, glass, and aramid fibers remain dominant, natural fibers like flax and hemp offer high performance and affordability with lower environmental impact. Natural-based yarns are finding applications in automotive, construction, consumer goods, and sports equipment. Hybrid yarns, blending natural and polymeric fibers, promote ecological solutions. This review outlines the benefits of natural-based hybrid yarns in thermoplastic composites, exploring production methods and current developments in the field. [ABSTRACT FROM AUTHOR]

The seamless integration of advanced triboelectric nanogenerators with fiber material has propelled the rapid advancement of intelligent wearable electronics. The overheating and mechanical abrasion associated with prolonged operation poses a significant challenge for conventional fiber‐based triboelectric materials. Aramid fibers, characterized by high thermal stability, ultra‐high mechanical strength, and excellent insulating properties, can effectively compensate for the limitations of triboelectric materials. However, the intrinsic advantages of aramid fiber triboelectric materials and their general structural design strategies have not yet to be comprehensively elucidated. In this review, the synthesis methods and development history of aramid fiber triboelectric materials in recent years are summarized. Importantly, the unique advantages and development potential of aramid fibers as triboelectric materials are systematically discussed, particularly regarding high‐temperature resistance, high strength, and electrical insulation. Furthermore, the latest advancements in the structural design and performance modulation of aramid fiber triboelectric materials are presented. The aramid fiber‐based self‐powered wearable electronics in high‐temperature warning, impact monitoring, and human energy harvesting are summarized. Finally, the challenges and opportunities facing the future development of aramid fiber‐based triboelectric nanogenerators are discussed. [ABSTRACT FROM AUTHOR]

Despite the preliminary success of transition metal‐catalyzed [3+2] annulation of amides with olefins, the corresponding radical‐type [3+2] annulation remains a laborious challenge. Herein we report the first photoredox‐catalyzed radical‐type [3+2] annulation of aromatic amides with olefins. We established an approach to generate unprecedented iminium radicals by reducing the oxyiminium intermediates, formed in situ from corresponding amides with Tf2O, via photoredox catalysis. The [3+2] annulation was achieved via stepwise radical process, instead of forming linear products via other pathways as previously reported. This annulation protocol exhibits excellent functional group tolerance, and a diversity of substrates are united under the photoredox conditions, affording iminium products that can be in situ diversified into 1‐indanones, enamines and amines. Mechanistic investigations indicate reduction of the oxyiminium intermediate to the iminium radicals by excited‐state of the photocatalyst initiates the catalytic cycle. [ABSTRACT FROM AUTHOR]

The document from Chemical Communications provides a comprehensive list of articles and research findings in the field of chemistry. It covers a wide range of topics such as photodynamic therapy, electrochemical methods for gas detection, and crystallography. The journal aims to showcase original discoveries and preliminary research that contribute to scientific progress. The Royal Society of Chemistry publishes this journal, which connects the global chemistry community and reinvests profits back into the field. [Extracted from the article]

Various sizing agents were prepared to enhance the interfacial properties between aramid fiber (AF) and polycarbonate (PC), as well as to enhance the mechanical properties of AF/PC composites. It was found that PC sizing agent, P‐GO sizing agent, and PSi‐GO sizing agent effectively coated the surface of AF from the FTIR and XPS and SEM results. The IFSS and mechanical properties of composites reinforced with fibers treated by the sizing agents exhibited significant improvement, as well as their single fiber tensile strength also improved. Specifically, when AF was treated with PSi‐GO sizing agent, the interfacial shear properties between AF and PC increased by a remarkable 78.69%, reaching 22.89 MPa compared to the original AF/PC composite, the tensile strength of the single‐filament exhibited an increment of 12.4% to 26.4 cN/dtex. Moreover, the tensile strength, flexural strength, and impact strength of the composite increased by 5.43%, 77.74%, and 54.71%, respectively. These improvement can be attributed to the GO with a higher concentration of chemical groups and excellent dispersion with modified with the silane agent. These findings suggest that coating the AF with sizing agents can effectively enhance its interfacial adhesion with the matrix, which is useful for its application as the reinforcement in the composites. Highlights: Adding GO to the sizing agent to change the Aramid fabric surface properties.Silane coupling agent was used to improve the dispersion of GO on the fiber surface.GO modified sizing agent can improve the flexural strength, tensile strength, and interlaminar shear strength of the composites. [ABSTRACT FROM AUTHOR]

Highlights Delamination restricts the out‐of‐plane loading capacity of carbon fiber reinforced polymers (CFRPs), posing a challenge in their structural applications. While interlaminar reinforcement using aramid fibers has emerged as a promising method to alleviate delamination issues, the effects of aramid fiber size and areal density on the flexural properties of reinforced CFRPs remain underexplored. This study investigated the reinforcing potential of different aramid fiber forms, including short aramid fibers, aramid pulp, and aramid nanofibers, through a three‐point bending test on CFRPs. The results revealed that short aramid fibers and aramid pulp provided better reinforcing effects than aramid nanofibers as their fiber lengths were optimal for the bridging mechanism. Specimens reinforced with 0.16 g/m2 short aramid fibers attained the highest flexural strength, with a 20.9% improvement compared to unmodified specimens. Increasing the areal reinforcement density led to thicker interlayers, which negatively impacted flexural strength. These findings provide valuable insights for optimizing the use of aramid fibers in the industrial manufacturing of CFRPs, considering both reinforcing effects and process efficiency. Different‐sized aramid fibers were used for interlaminar reinforcement of CFRPs. Influence of interlayer thickness on flexural properties was investigated. Up to 20.9% improvement in flexural strength was achieved. Potential applications of different‐sized aramid fibers were discussed. [ABSTRACT FROM AUTHOR]

The poor interlaminar fracture toughness is a critical limiting factor for the structural applications of aramid fiber/epoxy resin composites. This study investigates the effects of laser-induced graphene (LIG) and short Kevlar fibers on the interfacial toughness and damage detection of aramid composite materials. Mode II tests and tensile tests were conducted to evaluate mechanical properties and damage detection using the piezoresistive characteristics of LIG. The results indicate that LIG combined with short Kevlar fibers significantly enhances the interfacial toughness of the composites, achieving a 381.60% increase in initial Mode II fracture toughness. Although LIG reduced the tensile strength by 14.02%, the addition of short Kevlar fibers mitigated this effect, preserving the overall mechanical performance. Scanning electron microscopy (SEM) analysis revealed enhanced toughening mechanisms, including increased surface roughness, altered crack propagation paths, and fiber bridging. Additionally, LIG enabled real-time damage monitoring, showing a significant increase in resistance upon delamination or crack propagation and a marked increase in resistance upon the tensile fracture. This research indicates that the synergistic effects of LIG and short Kevlar fibers not only enhance the interlaminar toughness of aramid composites but also provide a novel strategy for effective damage detection in fiber-reinforced materials. [ABSTRACT FROM AUTHOR]

Alginate fibers have excellent flame-retardant properties and make up for other material defects by blending. To investigate the influence of the blending ratio of alginate fibers on the flame-retardant properties of waterproof and breathable layers for firefighting suits, this paper utilizes the needle-punching and hot-pressing nonwoven reinforcement processes to prepare waterproof and breathable layers based on alginate/aramid base cloths and conducts a series of performance tests on them. The results show that the char residue content of alginate blended base cloth is significantly improved relative to pure aramid, and the addition of alginate fibers to the base cloth of the waterproof and breathable layer improves its flame retardancy and thermal stability. The overall performance of the alginate/aramid blended base fabric waterproof and breathable layer was better than that of the aramid-based waterproof and breathable layer. Moreover, in the flame-retardant multilayer fabric system for firefighting apparel, the multilayer fabric system containing the alginate/aramid-based waterproof and breathable layer showed higher thermal protection performance. Therefore, the alginate/aramid-based waterproof and breathable layer can enhance the overall flame-retardant performance of firefighting clothing to a certain extent. [ABSTRACT FROM AUTHOR]

Conventional index-based testing of asphalt mixtures cannot accurately capture local deformation in a sample, limiting the usage of standard test measurements. The non-contact-based measurements proved effective to capture local deformation fields. This study aimed to capture the fatigue and thermal cracking behaviour of fiber-reinforced asphalt mixture (FRAM) by utilising digital image correlation (DIC). One binder (PG76-22), a diabase aggregate and three fibers (polyolefin/ aramid fibers (PFA) at 0.05% dosage and Sasobit-coated aramid fibers at 0.01% and 0.02% dosage) were used to prepare a total of four mixtures (one control and three FRAM). All these mixtures were produced at a local batch plant following manufacturer-recommended mixing methods. DIC analysis was performed for three-point bending beam (3PB) and disk shape compact tension (DCT) tests at intermediate temperature (25°C) and low temperatures of −12°C and −18°C. Based on index values from DCT and 3PB, the thermal and fatigue cracking performance enhancement was not significant. However, DIC analysis showed that, regardless of testing temperature, the crack propagated in a random pattern for FRAM, whereas the crack followed a relatively straight path for the control mix. Finally, based on DIC strain contours, FRAM mixtures exhibit distributed strain over a larger area compared to the control mix. [ABSTRACT FROM AUTHOR]

In situ generated nanosilica particles were grafted onto aramid nanofibers while modified with a blocked mercapto silane (3‐Octanoylthio‐1‐propyltriethoxysilane). Nanofibers were derived from macro aramid fibers (poly (p‐phenylene terephthalamide)). Fourier‐transform infrared spectroscopy and x‐ray photoelectron spectroscopy revealed that the direct condensation reaction between the silane's ethoxy groups and the nanofiber's hydroxyl or carboxylic groups forms SiO‐C bonds. Morphological analysis of nanofibers revealed the formation of nanosilica from unreacted residual silane on the modified nanofiber (A‐NM) surface. In situ silica formation caused SiOSi bond formation, according to the spectroscopic analysis. Styrene butadiene rubber‐silica composites with modified nanofiber additive were prepared. The bound rubber content and filler flocculation rate displayed an improvement in nanofiber dispersion and rubber‐nanofiber interaction after silane modification. Mechanical characteristics of the composites improved after rubber and modified nanofiber interaction, dispersion, and strengthening. The nanofibers evenly distributed during mixing, as proven by morphological analysis of composites. Incorporation of 1 phr of A‐NM increased tensile strength by 16% and abrasion resistance by 3.1%. Composite's rolling resistance indicator (6.2%) and winter traction indicator increased at high temperatures with 1 phr of A‐NM loading. This specialized filler decorated nanofibers could be used as energy‐efficient tire additives as an alternative to other trendy commercial materials. [ABSTRACT FROM AUTHOR]

Flax fiber/epoxy composites have attracted extensive attention in aviation applications due to the advantages of low density, remarkable mechanical properties and environmental friendliness. However, the interface compatibility between hydrophilic flax fiber and hydrophobic epoxy resin matrix is poor, which makes the lamination resistance of the composite insufficient, and affects the bearing capacity and service life of the material. Chopped fiber interlaminar toughening is an effective method to improve the interlaminar fracture toughness of composites. Besides, the numerical simulation based on cohesive zone models has also become an effective tool for analyzing interlaminar toughening in the composites. In this study, three different cohesive zone models, including bilinear, exponential and trilinear cohesive zone laws, are used to simulate the mode I interlaminar fracture behavior of chopped aramid fiber interleaved flax fiber/epoxy composites. The numerical results are analyzed and compared with the double cantilever beam (DCB) experimental results and digital image correlation(DIC)observations, summarizing the influence of different cohesive zone laws. The results show that bilinear and exponential cohesive zone models are unsuitable for simulating the interlaminar toughening effect of chopped fiber interleave due to the numerical results with no laddered or fluctuated descent. The trilinear cohesive zone model can effectively present the chopped fiber interlaminar toughening effect and behavior by including the toughening effects of fiber bridging and matrix failure so that fiber bridging failure mode and crack propagation behavior are similar to those observed with the DIC method. This research provides a rational basis for the chopped fiber interlaminar toughening design of flax fiber/epoxy composites. [ABSTRACT FROM AUTHOR]

In the study, flexural performances of FRP reinforced concrete (RC) slabs with different fiber and bar surface properties were investigated. Glass fiber reinforced polymer (GFRP), Carbon fiber reinforced polymer (CFRP), Aramid fiber reinforced polymer (AFRP) and Basalt fiber reinforced polymer (BFRP) steel reinforcements were used in the reinforcement of the slabs. A total of 27 slabs were produced in the dimensions of 1100–1100–100 mm and with the same reinforcement ratios as FRP and steel reinforcement and were tested with the four-point flexural test method. The flexural strength, moment capacity, toughness and ductility values of the slabs were calculated by determining their flexural behaviour, and the average values were compared. In the comparison, the behaviour of the FRP RC slabs was analysed by taking the steel RC slabs as reference. The effects of FRP fiber type and bar surface properties on slab behaviour were evaluated. The bending load-carrying capacity of AFRP and GFRP RC slabs with ribbed surfaces was 4% higher than those with sand-coated surfaces. In addition, the bending load-carrying capacity of BFRP and CFRP RC slabs with sand-coated surfaces was 13% and 16% higher than those with ribbed surfaces, respectively. The type of failure in slabs varies based on the type of reinforcement and the surface properties of the reinforcement. Three types of failures have been identified: flexural failure, shear failure, and flexural-shear failure. The ductility performance of steel RC slabs has been determined to be the highest, with a value of 9.45. When comparing toughness, sand-coated FRP bars exhibit toughness levels 8–40% higher than ribbed ones. Among the FRP RC slabs, sand-coated CFRP RC slabs provide the greatest contribution to flexural load-carrying capacities. [ABSTRACT FROM AUTHOR]

High-performance fibers have been widely used due to their special properties such as high strength, high modulus and high temperature resistance, and supercritical CO2 fluid technology provides new ideas and methods for ecological and low-carbon processing of high-performance fiber materials due to its low viscosity, high diffusivity, and significant plasticizing effect.This paper briefly describes the principles and advantages of supercritical CO2 fluid processing technology, reviews the research progress on the modification, dyeing, and functional finishing of high performance fibers such as aramid, ultra-high relative molecular mass polyethylene (UHMWPE), polyimide (PI), and polyphenylene sulfide (PPS) in supercritical CO2, and the challenges of supercritical CO2 fluid processing technology for high performance fibers were discussed. It is pointed out that the main trend of supercritical fluid processing technique for high-performance fiber is to explore novel principles and methods by multi-disciplinary cross-research, develop intelligent supercritical fluid processing equipment and supporting procedures, and design new types of dyeing and finishing agents and multi-functional technologies suitable for the supercritical CO2 fluid system. [ABSTRACT FROM AUTHOR]

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Aramid fiber (AF)-reinforced epoxy (EP) resin composite materials are widely used in the application of insulation rod-reinforced components, but the adhesion performance between AFs and EP resin is poor, which easily leads to interfacial defects and even gradually develops into breakdown, flashover, and other faults. In this study, a simple, environmentally friendly, diverse, and highly designable layer-by-layer self-assembly modification method was adopted to assemble aramid nanofibers/SiO2 onto the surface of AFs. The modified AFs were then used to produce composite materials with EP resin. By testing the interface breakdown, flashover, and leakage current of the AF/EP resin composite materials, the influence mechanism of AF surface modification on the material interface insulation performance was studied. The results show that the insulation performance of the modified composite material first increases and then decreases with the increase in the number of assembled layers, with the maximum increase in breakdown voltage being 93.56% and the maximum increase in flashover voltage being 30.91%. [ABSTRACT FROM AUTHOR]

Isoindolinones are vital heterocyclic compounds in medicinal chemistry, notable for their diverse bioactivities. Significant attention has been devoted to their preparation; however, existing methods are unsuitable for constructing unsubstituted 3‐methyleneisoindolin‐1‐ones. Herein, we present a rhodium(III)‐catalyzed method for synthesizing unsubstituted 3‐methyleneisoindolin‐1‐ones via C−H/N−H activation and annulation of N‐methoxybenzamides with potassium (ethenyl)trifluoroborate. This approach offers mild reaction conditions, high regioselectivity, and efficient yields. Interestingly, sterically demanding or heterocyclic N‐methoxyaromaticamides resulted in the formation of 2‐vinyl(hetero)aromatic amides instead of 3‐methyleneisoindolin‐1‐ones. Mechanistic insights suggest a rhodacycle intermediate pathway, highlighting the method's potential for developing new bioactive isoindolinone derivatives. [ABSTRACT FROM AUTHOR]

Silk‐based materials are sought after across various industries due to their remarkable properties, including high strength and flexibility. However, their practical application depends largely on how well these properties are maintained under different environmental conditions. Despite significant advancements in the large‐scale production of artificial silk fibers, the effects of temperature on their mechanical behavior are understudied. In this study, the mechanical properties of artificial spider silk fibers between −80 and +120 °C are examined and compared to both synthetic and natural silk fibers. The findings reveal that artificial silk fibers maintain their strength up to +120 °C, though the strain at break slightly decreases, remaining above 60%. At −80 °C, the fibers exhibit increased strength, but the strain at break is reduced. While these artificial fibers closely mimic the behavior of natural silk, they show a noticeable reduction in extensibility at low temperatures. Complementing experimental data, differential scanning calorimetry, and thermogravimetric analysis are also conducted, proposing a simple physical model to explain the observed temperature‐induced softening. Encouragingly, the degradation temperature of artificial silk is comparable to that of native silkworm and spider silk. This study underscores the importance of enhancing the mechanical robustness of artificial silk to expand its applications. [ABSTRACT FROM AUTHOR]

Lowering passenger vehicle weight is a major contributor to improving fuel consumption and reducing greenhouse gas emissions. One fundamental method to achieving lighter cars is to replace heavy materials with lighter ones while still ensuring the required strength, durability, and ride comfort. Currently, there is increasing interest in hybrid structures obtained through adhesive bonding of high-performance fiber-reinforced polymers (FRPs) to high-strength steel sheets. The high weight reduction potential of steel/FRP hybrid structures is obtained by the thickness reduction of the steel sheet with the use of a lightweight FRP. The result is a lighter structure, but it is challenging to retain the stiffness and load-carrying capacity of an unreduced-thickness steel sheet. This work investigates the bending properties of a non-reinforced DP780 steel sheet that has a thickness of 1.45 mm (S1.45) and a hybrid structure (S1.15/ACFRP), and its mechanical properties are examined. The proposed hybrid structure is composed of a DP780 steel sheet with a thickness of 1.15 mm (S1.15) and a hybrid composite (ACFRP) made from two plies of woven hybrid fabric of aramid and carbon fibers and an epoxy resin matrix. The hybridization effect of S1.15 with ACFRP is investigated, and the results are compared with those available in the literature. S1.15/ACFRP is only 5.71% heavier than S1.15, but its bending properties, including bending stiffness, maximum bending load capacity, and absorbed energy, are higher by 29.7, 49.8, and 41.2%, respectively. The results show that debonding at the interface between S1.15 and ACFRP is the primary mode of fracture in S1.15/ACFRP. Importantly, S1.15 is permanently deformed because it reaches its peak plastic strain. It is found that the reinforcement layers of ACFRP remain undamaged during the entire loading process. In the case of S1.45, typical ductile behavior and a two-stage bending response are observed. S1.15/ACFRP and S1.45 are also compared in terms of their weight and bending properties. It is observed that S1.15/ACFRP is 16.47% lighter than S1.45. However, the bending stiffness, maximum bending load capacity, and absorbed energy of S1.15/ACFRP remain 34.4, 11.5, and 21.1% lower compared to S1.45, respectively. Therefore, several modifications to the hybrid structure are suggested to improve its mechanical properties. The results of this study provide valuable conclusions and useful data to continue further research on the application of S1.15/ACFRP in the design of lightweight and durable thin-walled structures. [ABSTRACT FROM AUTHOR]

A method for the preparation of nitriles from primary amides using trichloroacetonitrile and a catalytic amount of cupric acetate is described. Using this method, amides including aromatic amides, aromatic heterocyclic amides and aliphatic amides were converted into the corresponding nitriles in moderate to good yields. Trichloroacetonitrile reacted with amide in the presence of cupric acetate to form trichloroacetamide, which has been isolated and confirmed. [ABSTRACT FROM AUTHOR]

Para-aramid fibers, known for their remarkable strength and thermal stability, are frequently employed in protective textiles for military and aerospace applications. However, continuous exposure to ultraviolet (UV) radiation can damage their protective characteristics. This study analyzes the ultraviolet protection factor (UPF) and UV transmittance of woven fabrics produced from 30/2 Ne spun para-aramid yarns in the warp and 10 Ne core-spun yarns in the weft. The weft yarns consisted of three sheath fibers—para-aramid, meta-aramid, and polyester—in combination with different specialty core materials. The results show significant differences in UPF before and after UV exposure, with para-aramid sheaths giving the highest improvement. UV exposure caused structural changes in the fibers, resulting in increased UV protection, particularly in fabrics with para-aramid sheaths. This study concludes that the combination of para-aramid fibers with specific core materials significantly enhances UV protection, making them well-suited for applications in high UV exposure environments. [ABSTRACT FROM AUTHOR]

In this paper, the usage of core-spun compound yarns in ballistic fabric to improve ballistic performance is considered, as with the use of core-spun compound yarns, the yarn friction inside the fabric is enhanced, and, therefore, the energy absorption capability of the fabric is expected to increase. Three types of fabric were developed and compared. Fa refers to a woven type made with 100% Kevlar® filament yarns. Fb was woven with core-spun compound aramid yarns, which were made of Kevlar® filament yarns spun with staple aramid fiber. Fc was woven with core-spun compound polyester yarns, which were made of Kevlar® filament yarns spun with staple polyester fiber. There were two main purposes for comparing these types. The first was to confirm if the ballistic performance could be improved with the usage of core-spun compound yarns instead of pure filament yarns. The second was to investigate if different compositions of spun fiber would influence ballistic performance. The research results are positive and quite interesting. They show that the usage of core-spun compound yarn could indeed help to increase ballistic performance and that core-spun compound aramid yarns are better than core-spun compound polyester yarns in this function. The research was carried out using both ballistic tests and FEA models. [ABSTRACT FROM AUTHOR]

FRCs (Fiber-Reinforced Composites) are materials that are being used increasingly more often in dentistry as an alternative to traditional restorations made of ceramics or metals. The aim of this study was to carry out a comparative analysis of the strength parameters of a light-curable dental composite reinforced with one single band and two single bands of artificial fibers. The specimens for the strength tests were prepared in accordance with the guidelines of the PN-EN ISO 4049:2019-07 international standard. The test material covered specimens of composite reinforced with single (one or two) bands of fibers. The following bands of fibers were used: carbon (WGL), aramid (AMD) and hybrid carbon–aramid (WGL-AMD). The presence of one single band of aramid fibers caused a three-fold increase in deflection, with a simultaneous increase in the Young's modulus of over 140%. The flexural strength of specimens reinforced with one single band of aramid fibers was higher by 280% than that control group specimens (KONT). To summarize the performed tests, the incorporation of carbon, aramid and hybrid carbon–aramid fibers into organic matrix has a significant impact on the values of the mechanical parameters of dental composites. The results indicate that particular attention should be paid to aramid fibers, which have rarely been used in dentistry so far. [ABSTRACT FROM AUTHOR]

This paper summarizes the results of a study that was conducted to evaluate the performance of field-produced aramid fiber-reinforced asphalt mixtures used for resurfacing applications and compare it to that of polymer-modified asphalt mixtures. Twelve test sections were constructed as part of resurfacing projects in Ohio. Two aramid fibers from different sources were used in these projects. During the construction of the test sections, loose asphalt mixtures were collected and were used to prepare samples. Different tests were conducted on the prepared samples. These included the following: semicircular bend and indirect tensile asphalt cracking to evaluate the cracking resistance of prepared samples, the asphalt concrete cracking device test to evaluate the low-temperature cracking resistance of prepared samples, and the Hamburg wheel tracking test to evaluate the resistance of samples to rutting and moisture damage. Results indicated that the effects of the addition of aramid fiber to asphalt mixture vary depending on the type of aramid fiber and mixture properties. In general, Fiber A and Fiber B significantly improved the cracking resistance of mixtures with PG 64-22. Furthermore, mixtures with PG 64-22 binder and aramid fibers had similar or higher cracking resistance as compared to those with PG 70-22M asphalt mixture. The addition of fibers improved the resistance of reinforced mixtures to rutting and moisture damage. The fibers slightly improved the low-temperature cracking resistance of asphalt mixtures. Statistical analysis of testing results indicated that the properties related to the cracking resistance of the fiber mixtures did not significantly change during production. [ABSTRACT FROM AUTHOR]

Fiber-reinforced composites were widely used in aerospace, automotive, and wind energy industries, due to their lightweight, high specific strength and stiffness, design flexibility, and durability. This study prepared hybrid fiber preforms using a three-dimensional braided technique. These preforms made of carbon fiber (CF) and aramid fiber (AF) were reinforced into resin-based (ER) composites by a vacuum infusion process (VIP). Our study focused on evaluating the mechanical properties of these composites under different blend arrangements and ratios, with four blend arrangements including layer-by-layer, half-by-half, bundle-by-bundle, and block-by-block. The results showed that the bending strain of the composites with a 3:1 aramid fiber/carbon fiber yarn ratio (3AF1CF) increased by 105.56% compared to that of CF/ER, and the addition of AF improved the toughness of the composite. The tensile strength and modulus of the composites with a 3:1 carbon fiber/aramid fiber yarn ratio (1AF3CF) were improved by 31.17% and 109.68%, respectively, compared to those of AF/ER, and the bending strength and modulus increased by 106.12% and 115.32%, respectively, and increasing the CF ratio thus significantly improved the mechanical properties of the composites. In addition, in four hybrid arrangements with the same AF/CF ratio, the aramid fiber/carbon fiber yarn ratio of 2:2 (2AF2CF-4) possessed the best mechanical properties, with tensile strength and of 608.36 MPa and 13.8 GPa, and bending strength and modulus of 417.203 MPa and 22.9 GPa, respectively. [ABSTRACT FROM AUTHOR]

Aerogels with ultrahigh porosity and large specific surface area have demonstrated great potential for capturing volatile organic compounds (VOCs). Especially, aerogel fiber aggregates with macropores formed by overlapping aerogel fibers and mesopores in the aerogel fibers might realize fast sorption kinetics and high sorption capacity simultaneously. However, how to develop fast fabrication and large‐scale production of aerogel fibers remains a challenge. Herein, a generic sol‐gel centrifugal spinning (SCS) strategy with a spinning rate capable of reaching 700 m min−1 is developed for producing aerogel fibers. The representative SCS aerogel fiber made from aramid nanofiber (ANF) dispersion exhibits a large specific surface area (313 m2 g−1) and high tensile strength (12.48 MPa). The SCS strategy is further applied to fabricate various kinds of aerogel fibers, including sodium alginate, cellulose, and chitosan. The ANF aerogel fiber aggregates exhibit superior VOC adsorption capacity of 438.0 mg g−1 under an ultrafast gas flux of 3.8 × 104 L m−2 h−1, which also has satisfactory cyclic stability. This work not only develops a powerful and generic strategy for fabricating aerogel fibers in large scale, but also provides inspiration for applying these SCS aerogel fibers in dynamic removal of VOCs and other environmental protection fields. [ABSTRACT FROM AUTHOR]

Reverse electrodialysis (RED) technology, relying on ion‐selective permeability membranes (ISPM), offers a direct means of harnessing osmotic energy from the salinity difference between seawater and freshwater. Critical technical challenges include limitations in ISPM's immobile charge carriers, transmembrane ionic internal resistance, and durability in water. Drawing inspiration from the subunit structure of the epithelial sodium channel (ENaC), an ISPM assembled using a supramolecular engineering strategy is introduced. This innovative approach enables the synergistic action of multiple molecular building blocks to mimic the distribution of ENaC subunit structures, strategically planning the placement of immobile charge carriers on nanofluidic channels. The design incorporates nano‐confined oxygen‐rich functionalized MXene (O‐MXene) and high‐strength polymer backbone aramid fibers to construct 3D nanofluidic channels with a high surface charge density. Enhanced by a bonding network of sodium carboxymethylcellulose, the ISPM achieved an exceptional output power density of 21.7 W m−2 and 46.0% energy conversion efficiency in a RED half‐cell system using natural seawater and river water, surpassing current technologies. This research not only advances RED technology but also provides biomimetic customization concepts for ISPM design across various applications, including flow batteries, fuel cells, and related fields. [ABSTRACT FROM AUTHOR]

ABSTRACT A series of N,N‐chelate half‐sandwich ruthenium complexes based on N‐phenylpicolinamide ligands has been prepared with good yields through a facile route. These air and moisture stable N,N‐chelate half‐sandwich ruthenium complexes showed good catalytic efficiency in transamidation reactions between aromatic amines and amides under mild reaction conditions. A variety of secondary amides was obtained in high yields under open flask condition with broad substrates and good group tolerance. The excellent catalytic activity, broad substrate range, and mild reaction conditions make this catalytic system a potential candidate for industrial production. In addition, the structure of the prepared ruthenium complex has been confirmed by single crystal X‐ray diffraction. [ABSTRACT FROM AUTHOR]

A facile and highly efficient chemoselective reduction of α,β‐unsaturated amides leading to saturated amide has been described. In situ generated nickel boride was found to act as an efficient reagent for the conjugate reduction. The reaction proceeds smoothly under an inert atmosphere at ambient temperature with a moderate to good yield. Both aliphatic and aromatic α,β‐unsaturated amides were found to be compatible with the reaction protocol. [ABSTRACT FROM AUTHOR]

A multi‐stage fiber spreading process for the preparation of high‐performance continuous aramid fiber reinforced nylon 12 (CAF/PA12) composites was proposed in this paper. The effects of spreading rod crown radius, spreading rod axis height and traction speed on fiber impregnation effect and filaments properties were investigated. The fiber volume fraction of the prepared filament was approximately 30%. And the maximum tensile strength and modulus of the filaments were 839.89 MPa and 41.35 GPa, which were 34.36% and 34.30% higher than unspreading filaments, respectively. The influences of printing process parameters such as printing temperature, the combination of layer thickness and printing spacing on the transverse tensile properties of the specimens were studied. Printed specimens reached a transverse tensile strength and tensile modulus of 13.988 MPa and 1.293 GPa, respectively. The influences on low velocity impact properties of the specimens were also investigated in terms of impact energy and printing stacking sequences. Results revealed that the impact threshold energy of orthotropic ([0/90/0/90]2) specimens was 50 J. Quasi‐isotropic ([0/45/90/−45]2) specimens exhibited the superior impact resistance with an impact load of 4.939 kN. Macro‐ and micro‐matrix crack, surface buckling, fiber fracture and delamination were the main failure modes of the specimens. Highlights: A novel thermoplastic composite filament forming process was proposed, and the filament forming equipment was designed and manufactured.Continuous aramid fiber‐reinforced PA12 filaments with about 30% fiber content were prepared by orthogonal tests under different forming process conditions, which showed maximum tensile properties of 839.89 MPa and 41.35 GPa, respectively.Spreading multiplication was positively related to filament tensile properties, which was major affected by the axial height of the spreading rod.Transverse tensile strength (13.988 MPa tensile strength and 1.293 GPa tensile modulus) of printed specimens was investigated under different printing parameters.Fiber orientation had a significant effect on the low‐velocity impact properties. Micro‐ and macro‐matrix crack, surface buckling, fiber fracture and delamination were the main failure modes of the low‐velocity impact specimens. [ABSTRACT FROM AUTHOR]

In this research, the effects of ultimate strain rate and environmental temperature on the mechanical performance of the aramid fiber bundles were experimentally investigated. The scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to detect the tensile failure mechanism of the aramid fiber bundle. The results indicated that the tensile strength, failure strain, elastic modulus, and toughness of the aramid fiber bundle were sensitive to the strain rate, which was represented as the typical bilinear monotonic relationships. In contrast, the impact of environmental temperature on the four parameters of aramid fiber bundle was more complex. The ultimate strength, failure strain and toughness of aramid fiber bundle increased with the temperature changing from −60 to 30°C, but rapidly decreased from 30 to 90°C. Finally, the dispersion of the mechanical performance was quantitatively analyzed based on the scale and shape parameters obtained from Weibull model. Highlights: Tensile tests for aramid fiber bundle under different strain rates and temperatures were conducted.Strain rate and temperature effects on tensile properties of fiber bundle were quantified.Tensile failure mechanism of fiber bundle was analyzed.Dispersion of the mechanical performance was quantitatively analyzed. [ABSTRACT FROM AUTHOR]

This article evaluates the values of the radial plasma frequency of a polymer thread made of fibers of carbon benzene rings with deposited chains of irregular aluminum nanoislands as a metamaterial with a negative dielectric constant (ENG material). When a pulsed high voltage of 1.6 kV/cm is applied, an electric discharge occurs and a highly conductive state above the surface is formed over a polymer thread of fibers of carbon benzene rings with chains of irregular aluminum nanoislands. [ABSTRACT FROM AUTHOR]

The mechanistic details of a reported allylation reaction are investigated by means of Stern–Volmer experiments and nanosecond transient absorption spectroscopy. Both reference substrates, i.e., an allylic chloride and a trifluoroacetamide, are inefficient quenchers but large quenching rate constants are observed upon the addition of Ni(COD)2 and a bisoxazoline ligand. The large quenching rate constants and absence of observable photoproducts are consistent with a mechanism that operates by energy transfer between the excited-state iridium photosensitizer and the nickel complex. [ABSTRACT FROM AUTHOR]

Concrete canvas is a composite material made with three-dimensional spacer fabric, which is manufactured by impregnating the fabric with cementitious materials. Concrete canvas has weaknesses in its mechanical properties including tensile strength. Strengthening concrete canvas with Fiber-reinforced polymer (FRP) materials can effectively improve its mechanical properties, particularly its tensile strength. Therefore, this study focuses on examining the impact of using FRP polymers to enhance the tensile properties of concrete canvas. Three types of fibers, namely Glass Fiber Reinforced Polymer (GFRP), Carbon Fiber Reinforced Polymer (CFRP) and Aramid Fiber Reinforced Polymer (AFRP; known as a Kevlar fiber) in various layer configurations, both warp and weft, were utilized to reinforce concrete canvas under tensile loading. The test results demonstrate that the use of FRP fibers significantly enhances the mechanical properties of concrete canvas. Specifically, single-layer glass fibers lead to considerable growth and reinforcement with carbon and Kevlar fiber layers results in more than five to seven times improvement in tensile strength compared to control concrete canvas. [ABSTRACT FROM AUTHOR]

The development of composite materials with excellent thermal conductivity is attracting extensive attention to meet the increasing heat concentration challenges in both power and electronic equipment. Previous strategies for improving the thermal conductivities usually accompanied by the cost of mechanical strength. Herein, we propose a new strategy for developing both mechanically strong and thermally conductive composite films. The aramid nanofibers (ANF) are well prepared with introducing Ag nanoflakes and graphene oxide (GO) via vacuum-assisted filtration and hot-pressing treatment. Results indicate the synergistic effects of low dimension materials have resulted in a tightly arranged phonon network construction. The in-plane thermal conductivity of the prepared ANF/Ag/GO film reaches 9.84 W m−1 K−1, about 371% higher than that of pure ANF. Meanwhile, the strong hydrogen bond formed between the functional group of GO and the amide group of ANFs plays a synergistic strengthening and toughening role at the complex interface, and the tensile strength reaches 231 MPa. We believe that these findings shed some light on the design and fabrication of multifunctional materials for thermal management applications. [ABSTRACT FROM AUTHOR]

A porous, crosslinked aromatic polyamide having COCl and COOH groups (referred to as PA herein) prepared had a mesoporous structure and comprised agglomerates of particles with average diameters of approximately 30 nm. The PA was found to swell with significant deformation in response to water vapor, but was almost unchanged after exposure to toluene vapor. The polymeric structure returned to its original porous morphology after removal of the solvents, demonstrating that the PA possessed affinity for specific solvents and shape memory. The chemical composition and porous structure of the PA were also not affected by heating to 330 °C. The COCl groups in the PA could be modified by reaction with 2,4,6‐triaminopyrimidine (TAP), resulting in a doubly crosslinked structure based on the reaction with the TAP as well as the existing amide moieties in the polymer. The degree of modification was highly dependent on the reaction solvent used. The porous structure of the PA was essentially unchanged after this modification. The TAP‐based crosslinks in the modified PA could be selectively cleaved along with vaporization of the TAP by heating at 330 °C, which no change to the porous structure. Thus, the PA showed excellent heat resistance and structural stability. [ABSTRACT FROM AUTHOR]

In the quest for sustainable and high-performance hydrogen fuel cells, proton exchange membranes (PEMs) stand as a pivotal research focus. To overcome the significant challenge posed by the traditional trade-offs between proton conductivity and mechanical stability, this work introduces liquid-crystal-modified aramid fibers (DBAF) with highly ordered molecular arrangements and abundant sulfonic acid groups on the side chains as proton-hopping sites into a sulfonated poly (ether ether ketone) (SPEEK) matrix. The inclusion of components not only improves the proton conductivity of the membrane, but also boosts its mechanical strength. The results of our study demonstrate that the externally attached sulfonic acid groups create extra channels for the transport of protons. Additionally, the organized and consistently stable hydrogen-bond network enables the Grotthuss transport mechanism within the SPEEK membrane. The 1 wt% DBAF-SPEEK composite membrane exhibits a maximum proton conductivity of 0.23 S cm−1 at 80 °C, representing a 64% increase over the baseline SPEEK membrane's 0.14 S cm−1. Simultaneously, the tensile strength at normal room temperature is 39.7 MPa, exhibiting an improvement of 86% compared to the initial value of 21.3 MPa. Additionally, the swelling ratio is lowered by 18.69%. Compared with the baseline membrane, the DBAF-enhanced SPEEK composite membrane exhibits superior mechanical stability and proton conductivity within a moderate temperature range (30–80 °C). Consequently, this work offers valuable insights for the development of novel proton-conductive materials. [Display omitted] • A Novel PEM developed using SPEEK and liquid-crystal-modified aramid fibers. • DBAF resolves trade-off between proton conductivity and mechanical stability. • Grafted sulfonic acid groups add new proton transport pathways. • Grotthuss mechanism dominates proton transport in the composite membrane. [ABSTRACT FROM AUTHOR]

Owing to their flexibility and high thermal resistance, para-aramid based Kevlar™ fabric substrates are an ideal candidate for obtaining flexible gas sensors for new-generation wearable technologies. The morphology of the surface of the substrate where the target gas comes into contact directly affects the important features of the sensor such as detection limit, selectivity, and response. In this context, a feasible technique is introduced to enhance the efficiency of flexible gas sensors utilizing ZnO/Kevlar™, entailing the modification of ZnO morphology. ZnO based gas sensing layers were deposited on Kevlar™ fabric substrates by a two-stage method. Initially, seed layer was produced on Kevlar™ fabric using the ultrasonic bath method, with five different seed layer processing times ranging from 1 min to 20 min. In the nucleation, all nanostructured layers were deposited by hydrothermal method with constant parameters and under the same conditions. As the seeding time was increased, nanorods (1D) formed on the surface became flakes (2D), leading to considerable improvement in NH3 gas sensing properties. The sensor with a 5-min seeding time showed a sensitivity of 49 % at an optimal operating temperature of 190 °C, while the sensor produced in 20 min showed the best response performance with 169 % at 130 °C for 50 ppm NH3 gas. The increase in seeding time not only reduced the operating temperature of the gas sensor through the conversion from 1D nanostructure to 2D, but also significantly increased the sensor response. Under constant hydrothermal conditions and solution concentration, the density per unit area increases. However, after 10 min of seeding, the length of nanorods shortens and turn into a rod-flake hybrid morphology. A superior sensor performance was demonstrated for the samples examined. The obtained results also showed that flexible Kevlar™ fabric could be a feasible and interesting substrate for nanostructured ZnO-based NH3 gas sensors. [Display omitted] [ABSTRACT FROM AUTHOR]

The demanding and rigorous modern work environments present significant challenges to the protective capabilities of engineering materials. Polyurea elastomers often face limitations in terms of inadequate strength and a lack of weather resistance, however, polyurea composites holds great promise in addressing these issues. This study prepared modified ultrafine aramid short fibers using a mechanochemical method. Subsequently, in‐situ polymerization was utilized to combine the modified ultrafine aramid short fibers (M‐AF) with polyurea, resulting in the synthesis of a composite material characterized by recyclability, robust weather resistance, and favorable mechanical properties. Subsequently, intensive researches were conducted on the mechanical properties, recyclability, self‐healing performance, weather resistance, and chemical medium resistance of the composites. The composite at 0.1 wt% of M‐AF exhibited improvements in tensile strength (27.2 ± 0.8 MPa) as well as obviously enhanced impact performance (428.8 ± 6 kJ/m2), and recovered most of its mechanical properties after recycling and self‐healing. Moreover, the composite exhibits excellent weather resistance and chemical resistance, enabling it to uphold its exceptional protective performance even in the face of challenging environments. Highlights: Ultrafine aramid fibers were prepared using a simple mechanochemical method.Mechanochemical methods were employed to surface modify aramid fibers.The composites have good strength, recyclability, weather resistance. [ABSTRACT FROM AUTHOR]