Journal articles: 'Aramid fibers'

1

Zhang, Su Feng, and Chun Lei Kang. "Crystal Structure Analysis on Aramid Fiber/Fibrids and Paper by Polarized Light Microscopy." Key Engineering Materials 531-532 (December 2012): 636–39. http://dx.doi.org/10.4028/www.scientific.net/kem.531-532.636.

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The crystal structure of aramid fibers is highly orientated. The structure of aramid fibers with various manufacturing processes and aramid paper sheets were analyzed and observed by using polarized light microscope (PLM). The change and its law of aramid fiber crystal structure in such processes as aramid fiber mamufaturing of aramid fiber/fibrids, forming of aramid paper sheets, and heat treatment were analysed. The relationship between the structural feature of aramid fibers and the performance of aramid paper was also discussed.

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Doriomedov, M. S. "ARAMID FIBER MARKET: TYPES, PROPERTIES, APPLICATION." Proceedings of VIAM, no. 11 (2020): 48–59. http://dx.doi.org/10.18577/2307-6046-2020-0-11-48-59.

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The article is devoted to the consideration of the world and Russian market of aramid fiber. Provides information about the approximate production of aramid fibers in general and by types: para- and meta-aramid. The main trade names of aramid fibers, production facilities, main aramid producers in the world and in Russia, information about the properties of some brands of aramid fiber and indicative percentages of various fields of application in the global and Russian consumption of aramid fibers are given.

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3

Lu, Zhaoqing, Yongsheng Zhao, Zhiping Su, Meiyun Zhang, and Bin Yang. "The Effect of Phosphoric Acid Functionalization of Para-aramid Fiber on the Mechanical Property of Para-aramid Sheet." Journal of Engineered Fibers and Fabrics 13, no. 3 (September 2018): 155892501801300. http://dx.doi.org/10.1177/155892501801300303.

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The mechanical properties of para-aramid sheet (PAS) are mainly dependent on the interfacial property between para-aramid chopped fibers and fibrids. However, the chemical inertness and smooth surface of para-aramid chopped fiber lead to the poor interfacial adhesion between para-aramid chopped fibers and fibrids. In this study, para-aramid chopped fiber was treated by phosphoric acid (PA) solution with different concentration in order to prepare PAS with high mechanical strength. It was shown that PA -treatment can increase the surface roughness and improve the surface oxygen-containing active groups of para-aramid chopped fibers. In addition, there is a critical value of PA-concentration (20%). Proper PA-treatment gives rise to an increased tensile strength of PAS from 2.41 to 3.41 kN/m by an increment of 41.49%. However, excessive PA -treatment results in a dramatic reduction of tensile strength for para-aramid fibers and also for PAS possibly due to the structure destruction of para-aramid fiber. This work shows a simple but highly-efficient approach for improving the mechanical property of PAS via PA-treatment of para-aramid chopped fibers, and simultaneously elaborating the reinforcing effects for high-performance PAS especially through optimizing the interfacial property between para-aramid chopped fibers and fibrids.

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Zhao, Hui Fang, and Mei Yun Zhang. "Surface Modification of Poly (M-Phenylene isophthalamide) Fibers and its Effect on the Mechanical Properties of Aramid Sheets." Advanced Materials Research 314-316 (August 2011): 205–8. http://dx.doi.org/10.4028/www.scientific.net/amr.314-316.205.

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In order to improve the bonding properties between poly (m-phenylene isophthalamide) (PMIA) fibers and PMIA-pulp and to improve the mechanical strength of aramid sheets, PMIA fibers have been treated with various chemical modifying agents. The surface morphology of the treated fibers has been analyzed and the mechanical properties of aramid sheets made from the treated PMIA fibers and PMIA-pulp have been investigated. The results show that silane coupling agent modification, phosphoric acid modification and nitrification/reduction modification of PMIA fibers are all helpful for improving the tensile strength and tear strength of aramid sheets, however, they have different effect on the mechanical strength of aramid sheets, and the concentration of chemical modifying agents also has considerable influence on the surface properties of aramid fibers and the mechanical properites of aramid sheets. Aramid handsheets made from PMIA fibers treated with 20% phosphoric acid have the highest mechanical strength, and the tensile strength and tear strength of them are 23.4% and 31.6% higher than that of aramid handsheets made from untreated fibers, respectively, because the treated fiber surface has more oxygenous functional groups and is more rough than the untreated fiber surface.

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5

Perelles, D. H., M. F. Medeiros, and M. R. Garcez. "Aplicação da análise hierárquica como ferramenta de tomada de decisão para escolha do compósito de reforço com polímeros reforçados com fibras." Revista ALCONPAT 3, no. 3 (September 30, 2013): 161–76. http://dx.doi.org/10.21041/ra.v3i3.52.

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RESUMOO reforço de estruturas com Polímeros Reforçados com Fibras (PRF) é uma alternativa que tem sido muito utilizada em intervenções executadas em elementos de concreto armado. A fibra de carbono é a mais empregada na formação dos compósitos de reforço utilizados em obras civis. Existe, no entanto, a possibilidade de se ampliar as opções de fibras formadoras do compósito utilizando as fibras de aramida e de vidro. Como uma ferramenta alternativa de tomada de decisão, o Método de Análise Hierárquica, baseado em critérios analisados de forma qualitativa e quantitativa, será utilizado neste trabalho para a avaliação das fibras de carbono, aramida e vidro, de forma a se obter qual material seria o mais apropriado para a execução de um reforço estrutural considerando como principais parâmetros de análise os custos dos materiais e as tensões e as deformações que os elementos poderão apresentar. A aplicação desta técnica de interpretação de resultados se mostrou muito útil, podendo ser considerada adequada para estudos que exijam uma tomada de decisão entre diferentes sistemas de reforço com PRF.Palabras clave: Reforço estrutural; polímeros reforçados com fibras; carbono; aramida; vidro; método da análise hierárquica.ABSTRACTStrengthening structures with Fiber Reinforced Polymers (FRP) is an alternative that has been used in interventions performed on reinforced concrete elements. Carbon fibers are the most used in the formation of composite reinforcement used in civil works. There is, however, possible to expand the options of forming fibers using the composite fibers of aramid and glass. As an alternative decision-making tool, the Analytic Hierarchy Process, based on criteria analyzed qualitatively and quantitatively, will be used in this work for the evaluation of carbon, aramid and glass fibers in order to obtain what material would be more suitable for the implementation of a structural reinforcement considering how key parameters of analysis material costs and the tensions and strains that may exhibit elements. This decision-making tool showed useful and can be considered suitable to select different FRP systems.Keywords: Structural strengthening; fiber-reinforced polymers; carbon; aramid; glass; hierarchical analysis method.

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6

Kausar, Ayesha, and Muhammad Siddiq. "Epoxy composites reinforced with multi-walled carbon nanotube/poly(ethylene glycol)methylether-coated aramid fiber." Journal of Polymer Engineering 36, no. 5 (July 1, 2016): 465–71. http://dx.doi.org/10.1515/polyeng-2015-0191.

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Abstract A novel type of aramid fibers coated with poly(ethylene glycol) methyl ether (PEGME)-modified multi-walled carbon nanotubes (MWCNTs) was designed using electrophoresis. Owing to the good interaction of MWCNT-PEGME with the matrix, the coated fibers were well dispersed in epoxy resin. Thin films of epoxy/aramid-MWCNT-PEGME were prepared by placing the modified aramid fibers in molds, and the epoxy resin was infused into them. 4,4′-Diaminodiphenylmethane was dissolved in epoxy before the resin was poured over the aramid fibers coated with MWCNT-PEGME. According to fracture surface studies, the modified fibers were completely miscible with the epoxy resin and the filler was dispersed well in the space between the aramid fibers. The tensile strength of neat resin was increased from 658 to 1198 MPa in 40 wt.% of fiber-loaded epoxy/aramid-MWCNT-PEGME 40 composite. The maximum flexural strength was also found to be higher for epoxy/aramid-MWCNT-PEGME 40 (1593 MPa). The glass transition temperature (Tg) was studied using differential scanning calorimetry, in the range of 164–173°C. The tensile strength, modulus, flexural strength, and Tg of epoxy/aramid fiber composites with unmodified fibers were found to be lower than those of epoxy/aramid-MWCNT-PEGME composites.

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7

Jin, Hui, Yi Yong Wang, and Cheng Wei Li. "Synthesis and Characterization of a Novel Aramid Fiber Liquid Crystalline Polymer." Applied Mechanics and Materials 395-396 (September 2013): 385–88. http://dx.doi.org/10.4028/www.scientific.net/amm.395-396.385.

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The-NH2 groups, as grafting initiators, are introduced to the surface of meta-aramid fibers by treating the fiber surface with dilute sodium hydroxide solution. A kind of new aramid fibers liquid crystalline polymer were synthesized by interfacial polymerization of mesogenic monomer DDBA, main-chain LCI containing sulfonate ionic monomer BY, sebacoyl dichloride and aramid fibers hydrolysed. The structure and properties of aramid fibers before and after modification were characterized by SEM, FTIR, and POM.

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8

Yu, Huan Yang, Li Yan Wang, and Guang Qing Gai. "Performance of Modified Aramid Fiber Reinforced Phenolic Foam." Advanced Materials Research 557-559 (July 2012): 258–61. http://dx.doi.org/10.4028/www.scientific.net/amr.557-559.258.

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A chemical modification was adopted to treat the surface of aramid fibers.The influences of aramid fibers on the friability and compression behavior of phenolic foam before and after modification were studied.Compared with unmodified aramid fiber-reinforced phenolic foam ,foam reinforced with modified aramid fibers exhibits significantly lower friability, higher compressive strength and compressive modulus. The thermal conductivity and Oxygen index of modified aramid fiber- reinforced phenolic foam hasn’t obviously been changed compared with the unmodified counterpart.

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9

Wang, Binhua, Guangzhi Ding, Gang Wang, and Sisi Kang. "Effects of resin pre-coating on interfacial bond strength and toughness of laminar CFRP with and without short aramid fibre toughening." Journal of Composite Materials 54, no. 25 (May 1, 2020): 3883–93. http://dx.doi.org/10.1177/0021998320923391.

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The brittle adhesive layer in carbon fiber-reinforced polymer (CFRP) laminates was strengthened by using short aramid fibers in this study. To ensure the feasibility and effectiveness of short aramid fiber interfacial toughening at the interface between the carbon-fiber face sheets, the self-prepared short aramid fibre tissue and the wettability treatment technology with resin pre-coating were applied to enable short aramid fibres to be well embedded in the uneven regions in the CFRP fabrics with fibres oriented at 0° and 90° to form a strong pulling resistance. The ultimate load and the mode I interlaminar fracture toughness have been improved by 75% and 103.9% from the double cantilever beam mode I crack propagation tests, respectively. The reinforcing mechanisms within the “composite adhesive layer” as a result of short aramid fibres are discussed together with detailed scanning electron microscopy observations and comparison test results.

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10

Noorvand, Hossein, Ramadan Salim, Jose Medina, Jeffrey Stempihar, and B. Shane Underwood. "Effect of Synthetic Fiber State on Mechanical Performance of Fiber Reinforced Asphalt Concrete." Transportation Research Record: Journal of the Transportation Research Board 2672, no. 28 (July 13, 2018): 42–51. http://dx.doi.org/10.1177/0361198118787975.

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It has been recognized that there exists a potential benefit from using synthetic fibers to reinforce asphalt mixtures. In these mixtures, the state of the fibers may play an essential role in their reinforcement function. This study aims to quantify the state of synthetic fiber distribution for two different aramid fiber–based asphalt mixtures and then show the impacts of fiber dispersion on modulus, rutting, and fatigue performance of each asphalt mixture in comparison with one another and with respect to an equivalent non-reinforced asphalt mixture. Both a quantitative and qualitative assessment of aramid fibers distribution as well as state of fiber are investigated using a fiber extraction procedure and microscopy imaging, respectively. The results suggested that a higher level of micro-fibrillation as well as high distribution of aramid fibers improved the rutting resistance of asphalt mixtures, while the distribution level of aramid fibers and fibers state did not affect the modulus and fatigue. These results are specific to the mixture studied but provide the first objective and detailed study describing fiber state, fiber dispersion, and performance.

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11

Tan, Hao, Hong Sheng Tan, Xin Lei Tang, Yan Gang Wang, and Li Ping Li. "Mechanical Properties and Dynamic Mechanical Behavior for Long Aramid Fiber Reinforced Impact Polypropylene Copolymer." Advanced Materials Research 591-593 (November 2012): 1079–82. http://dx.doi.org/10.4028/www.scientific.net/amr.591-593.1079.

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Composites of continuous aramid fiber reinforced impact polypropylene copolymer (IPC) were prepared using a cross-head impregnation mold by self-design fixed on a single screw extruder, and pelleted by a pelleter for injection molding to prepare testing specimens. The mechanical properties of long aramid fibers reinforced impact polypropylene copolymer (IPC) composites were studied. Micrographs of fracture surface of tensile specimens and dynamic mechanical behavior for the composites were analyzed by scanning electron microscope (SEM) and dynamic mechanical analyzer (DMA). The results of experiments show that, the tensile and flexural strengths increased obviously with the aramid fibers content in the composites. SEM results show the compatibility between the aramid fiber and matrix is very poor. The results of the dynamic mechanical behavior of long aramid fibers reinforced IPC composites show that the composite deformation resistance and glass transition temperature increased evidently with the addition of aramid fibers.

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12

Shi, Lei, Xu Pin Zhuang, Xiao Ning Jiao, Men Qin Li, Hong Jun Li, and Bo Wen Cheng. "Research on Properties of Aramid Fiber Needle-Punched Nonwoven Fabrics." Advanced Materials Research 332-334 (September 2011): 1253–56. http://dx.doi.org/10.4028/www.scientific.net/amr.332-334.1253.

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Aramids fibers are among the best known of the high-performance, synthetic, organic fibers. Needle-punched nonwoven fabrics with various structures were manufactured and their physical properties, structure, thermal insulation property and acoustic absorption property were examined. The results show that the aramid fiber needle-punched nonwoven fabrics possess good performance at thermal and acoustic insulation besides light mass and inherent flame-resistant.

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13

Deng, Tingting, Guangxian Zhang, Fangyin Dai, and Fengxiu Zhang. "Mild surface modification of para-aramid fiber by dilute sulfuric acid under microwave irradiation." Textile Research Journal 87, no. 7 (March 22, 2016): 799–806. http://dx.doi.org/10.1177/0040517516639831.

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In aramid fiber-reinforced composites manufacturing, para-aramid fiber requires surface modification to improve its interfacial adhesion with matrix materials. In this study, aramid fiber was modified with dilute sulfuric acid, which was gradually concentrated under microwave irradiation. Results showed that the aramid fiber could be efficiently modified. Sulfonic acid groups were introduced on the surface of the aramid fiber, as confirmed by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The breaking strength and thermal stability of the modified aramid fiber were not adversely affected. When the concentration of sulfuric acid was 30.0 g/L, the breaking strength of the aramid fiber remained at 90.7% of the original value, and the number of sulfonic acid groups of 1 g modified aramid fibers was 1.38 × 10–5 mol/g. Thermogravimetric and X-ray diffraction analyses showed that the main structure of the aramid fibers was not affected. The aramid fiber surface was not severely etched, as evidenced by scanning electron microscopy images. Therefore, this modifying method involving a gradual change in sulfuric acid concentration may be widely applied in many fields.

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Opwis, Klaus, Bilal Celik, Rainer Benken, Dierk Knittel, and Jochen Stefan Gutmann. "Dyeing of m-Aramid Fibers in Ionic Liquids." Polymers 12, no. 8 (August 14, 2020): 1824. http://dx.doi.org/10.3390/polym12081824.

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Aramids represent a class of high-performance fibers with outstanding properties and manifold technical applications, e.g., in flame-retardant protective clothing for firefighters and soldiers. However, the dyeing of aramid fibers is accompanied by several economic and ecological disadvantages, resulting in a high consumption of water, energy and chemicals. In this study, a new and innovative dyeing procedure for m-aramid fibers using ionic liquids (ILs) is presented. The most relevant parameters of IL-dyed fibers, such as tensile strength, elongation and fastness towards washing, rubbing and light, were determined systematically. In summary, all aramid textiles dyed in ILs show similar or even better results than the conventionally dyed samples. In conclusion, we have successfully paved the way for a new, eco-friendly and more sustainable dyeing process for aramids in the near future.

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Gupta, Anik, Pedro Lastra-Gonzalez, Daniel Castro-Fresno, and Jorge Rodriguez-Hernandez. "Laboratory Characterization of Porous Asphalt Mixtures with Aramid Fibers." Materials 14, no. 8 (April 13, 2021): 1935. http://dx.doi.org/10.3390/ma14081935.

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Recent studies have shown that fibers improve the performance of porous asphalt mixtures. In this study, the influence of four different fibers, (a) regular aramid fiber (RegAR), (b) aramid fiber with latex coating (ARLat), (c) aramid fiber with polyurethane coating (ARPoly), (d) aramid fiber of length 12 mm (AR12) was evaluated on abrasion resistance and toughness of the mixtures. The functional performance was estimated using permeability tests and the mechanical performance was evaluated using the Cantabro test and indirect tensile strength tests. The parameters such as fracture energy, post cracking energy, and toughness were obtained through stress-strain plots. Based on the analysis of results, it was concluded that the addition of ARLat fibers enhanced the abrasion resistance of the mixtures. In terms of ITS, ARPoly and RegAR have positively influenced mixtures under dry conditions. However, the mixtures with all aramid fibers were found to have adverse effects on the ITS under wet conditions and energy parameters of porous asphalt mixtures with the traditional percentages of bitumen in the mixture used in Spain (i.e., approximately 4.5%).

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Lu, Zhao Qing, Mei Yun Zhang, Li Hua, and Guang Yun Zhu. "Study on Improvement Effect of Aramid Fiber and PVA Fiber on of Mica Paper Strength and Dielectric Properties." Advanced Materials Research 214 (February 2011): 508–12. http://dx.doi.org/10.4028/www.scientific.net/amr.214.508.

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In order to improve the properties of mica paper, aramid fiber and PVA fiber were employed in mica paper as additive. Aramid fiber can act as skeleton and improve the dielectric strength of mica paper greatly accordingly at the optimum dosages of aramid fiber, 4%. When 3% of PVA fibers were added the tensile strength of mica paper increased significantly. It is because PVA fibers can smelt and act as bond for mica flake and aramid fiber under high temperature. The optimum beating degree of aramid fiber was 35 oSR, and the optimum drying temperature was 100°C. Compared with traditional mica paper, dielectric strength of composite mica paper with aramid fiber and PVA fiber increased above 25% and tensile strength increased 2.30 times under this optimum condition. In addition, the insulation performance of composite mica paper also improved substantially.

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17

Zhu, Caizhen, Xiaofang Liu, Jing Guo, Ning Zhao, Changsheng Li, Jie Wang, Jianhong Liu, and Jian Xu. "Relationship between performance and microvoids of aramid fibers revealed by two-dimensional small-angle X-ray scattering." Journal of Applied Crystallography 46, no. 4 (June 22, 2013): 1178–86. http://dx.doi.org/10.1107/s0021889813010820.

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Although the crystal structure in aramid fibers and the relationship between the size and orientation of crystallites and the performance of a material have been explored in detail, the effect of microvoids in an aramid fiber on its performance is still not clear. However, it is known that the mechanical properties depend strongly on the fiber morphology. In the present research, two-dimensional small-angle X-ray scattering is applied to characterize the microvoids in aramid fibers. Pauw's two-dimensional full pattern fitting method and scattering model have been enhanced by introducing orientation parameters, such as zenith angle distribution and azimuthal angle distribution, and instrumental parameters like point spread function and beam profile function. A series of aramid fibers with different strengths were studied using the new two-dimensional full pattern fitting method to extract the microvoid parameters from the scattering patterns. The results show that the microvoids in the aramid fiber affect the fiber strength directly. The greater the number of spherical microvoids and the larger the ellipsoidal microvoids, the weaker the aramid fiber.

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Li, Long, and Xue Yu Hu. "Study on the Surface Metallization of Aramid Fibers." Advanced Materials Research 503-504 (April 2012): 1216–19. http://dx.doi.org/10.4028/www.scientific.net/amr.503-504.1216.

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In this paper, aramid fiber surface metallization was investigated by electroless nickel plating technology. Acid nickel plating and alkaline nickel plating of aramid fiber was compared. Through experiment, it was shown that the temperature of alkaline nickel plating was lower compared with acid nickel plating, and resistance of metalized aramid fibers by alkaline nickel plating was 36.8Ω•cm, and the resistance by acid plating was 51.2Ω•cm. The surface morphology of fibers was observed using SEM

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Abu Obaid, A., J. M. Deitzel, J. W. Gillespie, and J. Q. Zheng. "The effects of environmental conditioning on tensile properties of high performance aramid fibers at near-ambient temperatures." Journal of Composite Materials 45, no. 11 (March 8, 2011): 1217–31. http://dx.doi.org/10.1177/0021998310381436.

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Aramid and aramid copolymer fibers are used in a wide variety of military and civilian applications; however, the long-term effects of environmental exposure on tensile properties are still not well understood. The current effort investigates the effect of hygrothermal conditioning on the tensile properties of Kevlar® KM2 ®, Twaron®, and the newly available Russian copolymer, Armos® high performance fibers. Moisture uptake studies show that at room temperature, water diffuses more slowly into the copolymer Armos ® (D = 8.7 × 10-13 cm2/s) compared to the Kevlar® KM2® and Twaron® homopolymers (D = 2.16 × 10-12 cm2/s and D = 1.8 × 10 -12 cm2/s, respectively). Tensile properties have been measured for these aramid fibers that have been conditioned in water at 40°C, 60°C, 80°C, and 100°C for periods of 17 and 34 days. For both aramid and aramid copolymer fibers, hygrothermal conditioning did not significantly change fiber tensile properties below 80°C. At the most extreme condition of 100°C, 34 days, aramid fibers showed significant loss of tensile strength (58% for KM2 and 34% for Twaron®), while a reduction in tensile strength of 13% (Armos®) was observed for aramid copolymer (Armos®) fibers. Conditioned fibers exhibited no significant change in mass as a result of the conditioning procedure and FTIR spectroscopy results did not indicate signs of chemical or thermo-oxidative change due to hygrothermal conditioning. These results suggest that in aramid fibers, the primary mechanism of degradation at temperatures between 80°C and 100 °C is due to the ingress and egress of moisture in the highly ordered core structure of the fiber. The presence of water in the intercrystalline regions of the fiber core enable segmental chain motion that can relax tie molecules, alter crystal orientation, and change apparent crystallite size. Because of differences in molecular architecture and phase morphology, the aramid copolymer, Armos®, is less susceptible to degradation of tensile properties under these conditions.

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Hintze, C., M. Shirazi, S. Wiessner, A. G. Talma, G. Heinrich, and J. W. M. Noordermeer. "INFLUENCE OF FIBER TYPE AND COATING ON THE COMPOSITE PROPERTIES OF EPDM COMPOUNDS REINFORCED WITH SHORT ARAMID FIBERS." Rubber Chemistry and Technology 86, no. 4 (December 1, 2013): 579–90. http://dx.doi.org/10.5254/rct.13.87977.

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ABSTRACT There is a renewed interest in the application of short aramid fibers in elastomers because of the considerable improvement in mechanical and dynamic properties of the corresponding rubber composites. Possible applications of short aramid fiber–reinforced elastomers are tires, dynamically loaded rubber seals, diaphragms, engine mounts, transmission belts, conveyer belts, and hoses. Our studies are related to the investigation of dispersion, length distribution, and the fiber–matrix interaction of two types of short aramid fibers, standard coated and resorcinol formaldehyde latex (RFL) coated, in ethylene–propylene–diene rubber (EPDM). Because the detection of the polymer fiber morphology in rubber compounds is hampered in the presence of carbon black, which is typically used in industrial elastomer compounds, fiber length, fiber length distribution, and dispersion are investigated in corresponding carbon black–free model compounds. Optical methods, scanning electron microscopy, and tensile testing are employed to explore the short aramid fiber–reinforced elastomer composites. The effects of morphology and fiber–matrix interaction on the mechanical properties of composites are discussed. Regarding fiber type, it is shown that co-poly-(paraphenylene/3,4′-oxydiphenylene terephthalamide) (PP/ODPTA) fibers end up with a higher final length than does poly(para-phenylene terephtalamide) (PPTA), which results in considerably higher mechanical properties of corresponding rubber compounds. For each fiber type, the higher final length as a result of RFL coating and the interaction with the rubber matrix are the key factors that overcome even the negative effect of poorer dispersion of RFL-coated fibers. The differences between the short aramid fibers and aramid cords regarding the RFL coating are also discussed.

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Talikoti, Rajashekhar, and Sachin Kandekar. "Strength and Durability Study of Concrete Structures Using Aramid-Fiber-Reinforced Polymer." Fibers 7, no. 2 (January 26, 2019): 11. http://dx.doi.org/10.3390/fib7020011.

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Fiber-reinforced polymer (FRP) is an important material used for strengthening and retrofitting of reinforced concrete structures. Commonly used fibers are glass, carbon, and aramid fibers. The durability of structures can be extended by selecting an appropriate method of strengthening. FRP wrapping is one of the easiest methods for repair, retrofit, and maintenance of structural elements. Deterioration of structures may be due to moisture content, salt water, or contact with alkali solutions. Using FRP, additional strength can be gained by structural elements. This paper investigates the durability of aramid-fiber-wrapped concrete cube specimens subjected to acid attack and temperature rise. The study focuses on the durability of aramid-fiber-wrapped concrete by considering the compressive strength parameter of the concrete cube. Concrete cubes are prepared as specimens with a double wrapping of aramid fibers. Diluted hydrochloric acid solution is used for immersion of specimens for curing periods of 7, 30, and 70 days. The aramid-fiber wrapping reduces weight loss by 40% and improves compressive strength by 140%. In a fire resistance test, the specimens were kept in a hot air oven at a temperature of 200 °C at different time intervals. Even after fire attack, weight loss in specimens reduced by 60%, with about 150% enhancement in compressive strength due to aramid fiber.

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Shirazi, M., and J. W. M. Noordermeer. "FACTORS INFLUENCING REINFORCEMENT OF NR AND EPDM RUBBERS WITH SHORT ARAMID FIBERS." Rubber Chemistry and Technology 84, no. 2 (June 1, 2011): 187–99. http://dx.doi.org/10.5254/1.3570531.

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Abstract Among short fiber reinforced composites, those with rubbery matrices have gained great importance due to the advantages they have in processing and low cost, coupled with high strength. These composites combine the elastic behavior of rubbers with strength and stiffness of fibers. Aramid fibers have been chosen because of their significantly higher modulus and strength, compared to other commercial fibers. Compounds based on NR and EPDM are prepared. Short aramid fibers with different kinds of surface treatments, standard finish, and resorcinol formaldehyde latex (RFL)-coating result in different rubber–fiber interfaces. The reinforcing effect of these short aramid fibers is characterized by mechanical and viscoelastic experiments, and by studying the fracture surfaces with electron microscopy techniques. Related to the fiber coating and rubber curing system, sulfur- or peroxide-based, different reinforcement mechanisms are observed, where the combination of peroxide-cured EPDM with RFL-treated fibers is the only case showing clear signs of chemical adhesion. In all other combinations there are only indications of mechanical interactions of the fibers with the rubber matrices, due to bending/buckling of fibers, dog-bone shaped fiber ends, and surface roughness due to the RFL-coating.

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Khafidh, M., D. J. Schipper, M. A. Masen, N. Vleugels, W. K. Dierkes, and J. W. M. Noordermeer. "Validity of Amontons’ law for run-in short-cut aramid fiber reinforced elastomers: The effect of epoxy coated fibers." Friction 8, no. 3 (October 15, 2019): 613–25. http://dx.doi.org/10.1007/s40544-019-0311-5.

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Abstract Friction between two contacting surfaces is studied extensively. One of the known friction theories is Amontons’ law which states that the friction force is proportional to the normal force. However, Amontons’ law has been found to be invalid for elastomers. In the present study, the validity of Amontons’ law for short-cut aramid fiber reinforced elastomers is studied. Two types of fillers are used to reinforce the elastomers, namely highly dispersible silica and short-cut aramid fibers. Short-cut aramid fibers with two different surface treatments are used, namely non-reactive fibers with standard oily finish (SF-fibers) and fibers treated with an epoxy coating (EF-fibers). A pin-on-disc tribometer is used to investigate the frictional behavior of the composites in sliding contact with a granite counter surface. The results show that, after the run-in phase, Amontons’ law is valid for those composites that are reinforced by short-cut aramid fibers (without reinforcing filler, i.e., silica) if the contact pressure is below a threshold value. However, once the contact pressure exceeds this threshold value, Amontons’ law will be invalid. The threshold contact pressure of the composites containing EF-fibers is higher than of the composites containing SF-fibers. The composites that are reinforced by silica and short-cut aramid fibers do not follow Amontons’ law.

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Lu, Zhao Qing, Qiang Xu, Zhi Jie Wang, and Zhen Wu. "Effect of Properties of Polyimide Fiber Paper-Based Materials by Different Paper-Making Process." Advanced Materials Research 631-632 (January 2013): 603–7. http://dx.doi.org/10.4028/www.scientific.net/amr.631-632.603.

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Polyimide fibers and polyamide acid fibers was used as main materials to produce Polyimide fiber paper. A certain amount of PEO and aramid pulp was added and the sheet was treated by immersion and hot pressing in specified process. The experimental results showed that when the dosage of PEO and aramid pulp were 0.06% and 6% respectively, the sheet tended to present more excellent strength properties and electrical performance compared with sheet using single polyimide fibers as the main fiber materials.

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Pahomov, K. S., Yu V. Antipov, I. D. Simonov-Emelianov, and A. A. Kulkov. "Effect of sorption of epoxy binding components on aramide fiber properties." Plasticheskie massy, no. 3-4 (June 24, 2019): 7–10. http://dx.doi.org/10.35164/0554-2901-2019-3-4-7-10.

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The inﬂuence of an epoxy binder of complex composition and its individual components on the sorption and physicomechanical characteristics of domestic aramid fibers is considered. The data on diffusion mass transfer of epoxy binder and its individual components into aramid fiber of various grades are obtained. It has been established that the components of the binder, after penetrating into aramid fibers, can change their macrostructure, however, this practically does not lead to a decrease in their strength.

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Bulut, Mehmet, Ömer Yavuz Bozkurt, and Ahmet Erkliğ. "Damping and vibration characteristics of basalt-aramid/epoxy hybrid composite laminates." Journal of Polymer Engineering 36, no. 2 (March 1, 2016): 173–80. http://dx.doi.org/10.1515/polyeng-2015-0168.

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Abstract Damping and vibration characteristics of basalt-aramid/epoxy hybrid composites with different basalt/aramid fiber mixing ratios were investigated. Unidirectional basalt and twill weave aramid fibers were used as reinforcement. Non-hybrid basalt/epoxy and aramid/epoxy composite laminates were also fabricated for comparison. Dynamic characteristics of the composite laminates were determined experimentally using dynamic modal analysis. Damping properties were calculated with the logarithmic decrement method using a vibration response envelope curve. Loss modulus, storage modulus and damping ratio of the structures were also considered. It was observed that the results of hybrid configurations showed a distribution between non-hybrid basalt/epoxy and aramid/epoxy composites. Furthermore, the employment of aramid fibers in composite laminates enhances the damping properties of laminates, but reduces the strength values.

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Kalajahi, Pouya Faraji, Arman Shahbazi, Karim Shelesh-Nezhad, and Naser Arsalani. "The effects of aramid short fiber and CaCO3 nanoparticles inclusions on the elastic, damping, and thermal behavior of polypropylene composite." Journal of Thermoplastic Composite Materials 33, no. 12 (April 8, 2019): 1707–20. http://dx.doi.org/10.1177/0892705719835285.

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Aramid short fiber (ASF) and calcium carbonate (CaCO3) nanoparticle were incorporated into polypropylene (PP) in an attempt to enhance the elastic, damping, and thermal performances. Different samples were melt mixed by employing a counter rotating twin-screw extruder and then compression molded using hot and cold presses, respectively. Scanning electron microscopy (SEM) studies displayed good dispersion and anchoring effect of the aramid fibers within the PP matrix. Differential scanning calorimetry (DSC) indicated higher crystal nucleating effect for the CaCO3 nanoparticles when compared to that of the aramid fibers. The influences of aramid fiber and CaCO3 nanoparticle on the elastic and damping components and glass transition temperature of composites were studied using a dynamic mechanical thermal analyzer under the fixed oscillation frequency, constant amplitude, temperature sweep, and dual cantilever geometry. The additions of aramid fiber and calcium carbonate (CaCO3) into PP noticeably increased the storage and loss moduli over a wide range of temperature (−50 to 150 °C). However, the effect of ASF was more prominent particularly at high temperatures. The incorporation of aramid fibers into PP enhanced the storage and loss moduli equal to 74% and 67%, respectively, at 100°C. Moreover, flexural tests under quasi-static loading were carried out, and the results indicated a greater capacity for the dynamic mechanical thermal analysis as compared to the simple mechanical tests in evaluating the composites. The anchoring effect of aramid fiber in PP matrix and the presence of CaCO3 nanoparticles in PP-aramid fiber interphase were found to be the key factors in achieving the improved rigidity, damping, and heat performances in PP/ASF/CaCO3 composites.

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Lee, Jaewoong, R. M. Broughton, S. D. Worley, and T. S. Huang. "Antimicrobial Polymeric Materials; Cellulose and m-Aramid Composite Fibers." Journal of Engineered Fibers and Fabrics 2, no. 4 (December 2007): 155892500700200. http://dx.doi.org/10.1177/155892500700200404.

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Cellulose and m-aramid were dissolved in an ionic liquid, and dry-jet wet spinning was employed to prepare composite fibers which could be rendered antimicrobial through exposure to chlorine bleach. The small domains of the m-aramid allowed a much higher accessibility and degree of chlorination than has been reported even for 100% m-aramid fibers. The mechanical properties including denier, tenacity, and strain at break were evaluated. The chlorinated composite fiber inactivated both Gram-positive and Gram-negative bacteria. The antimicrobial activity was retained after repeated washing and recharging.

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Lei, Xudong, Kailu Xiao, Xianqian Wu, and Chenguang Huang. "Dynamic Mechanical Properties of Several High-Performance Single Fibers." Materials 14, no. 13 (June 25, 2021): 3574. http://dx.doi.org/10.3390/ma14133574.

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High-performance fiber-reinforced composites (FRCs) are widely used in bulletproof structures, in which the mechanical properties of the single fibers play a crucial role in ballistic resistance. In this paper, the quasi-static and dynamic mechanical properties of three commonly used fibers, single aramid III, polyimide (PI), and poly-p-phenylenebenzobisoxazole (PBO) fibers are measured by a small-scale tensile testing machine and mini-split Hopkinson tension bar (mini-SHTB), respectively. The results show that the PBO fiber is superior to the other two fibers in terms of strength and elongation. Both the PBO and aramid III fibers exhibit an obvious strain-rate strengthening effect, while the tensile strength of the PI fiber increases initially, then decreases with the increase in strain rate. In addition, the PBO and aramid III fibers show ductile-to-brittle transition with increasing strain rate, and the PI fiber possesses plasticity in the employed strain rate range. Under a high strain rate, a noticeable radial splitting and fibrillation is observed for the PBO fiber, which can explain the strain-rate strengthening effect. Moreover, the large dispersion of the strength at the same strain rate is observed for all the single fibers, and it increases with increasing strain rate, which can be ascribed to the defects in the fibers. Considering the effect of strain rate, only the PBO fiber follows the Weibull distribution, suggesting that the hypothesis of Weibull distribution for single fibers needs to be revisited.

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Pincheira, Gonzalo, Cristian Canales, Carlos Medina, Eduardo Fernández, and Paulo Flores. "Influence of aramid fibers on the mechanical behavior of a hybrid carbon–aramid–reinforced epoxy composite." Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications 232, no. 1 (October 28, 2015): 58–66. http://dx.doi.org/10.1177/1464420715612827.

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This article is focused on the study of the contribution of aramid fibers in a hybrid carbon–aramid fiber twill weave used to reinforce epoxy resin. To evaluate the influence of the aramid fibers, a comparative study between carbon and carbon–aramid woven–reinforced composites, considering the mechanical behavior of both materials under several loading conditions, is performed. The tests used in this study are meant to analyze the effect of aramid reinforcements on the composite stiffness, strength, impact, and fracture performance. Higher values of energy absorption and fracture toughness were exhibited by the carbon–aramid composite. The mechanical tests performed indicated that the aramid phase present in the hybrid carbon–aramid composite induced an important enhancement on the impact (37.9% in energy absorption) and fracture resistance (12.7% for fracture initiation and 43% for steady state regime), compared to small reductions on the material stiffness. In addition, the ultimate strain and the through thickness compression strength were favorably affected, with an increase up to 19.5% and 8.3%, respectively, by the presence of aramid fiber that presents a more ductile response with respect to the carbon reinforcement.

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31

Song, Ying Deng, Bin Tai Li, and Li Ying Xing. "Structure and Compressive Property of Heterocyclic Aramid Fiber." Materials Science Forum 898 (June 2017): 2158–65. http://dx.doi.org/10.4028/www.scientific.net/msf.898.2158.

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The F-3 fiber is a trade name of a recently developed type of heterocyclic para-aramid fibers in China. To investigate the relationship between structure and compressive properties for F-3 fiber, the structural parameters and compressive strength have been analyzed in detail compared with the Kevlar-49 fiber. The structural parameters were determined by wide-angle X-ray diffraction (WAXD) analysis and sonic velocity method. The results showed that the orientation of chains of F-3 fiber was higher than that of Kevlar-49 fiber. The results of the tensile recoil method showed that F-3 and Kevlar-49 fibers had approximate compressive strength. The analysis of relation between structure and mechanical properties suggested that the combination of orientation parameter and shear modulus between adjacent chains resulted in the approximate compressive strength of F-3 and Kevlar-49 fibers.

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32

Sun, Hui, Haijuan Kong, Haiquan Ding, Qian Xu, Juan Zeng, Feiyan Jiang, Muhuo Yu, and Youfeng Zhang. "Improving UV Resistance of Aramid Fibers by Simultaneously Synthesizing TiO2 on Their Surfaces and in the Interfaces Between Fibrils/Microfibrils Using Supercritical Carbon Dioxide." Polymers 12, no. 1 (January 7, 2020): 147. http://dx.doi.org/10.3390/polym12010147.

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Aramid fibers with low density and high strength, modulus, and thermal resistance are widely used in applications such as bulletproof vests and cables. However, owing to their chemical structure, they are sensitive to ultraviolet light, which degrades the fibers’ useful mechanical properties. In this study, titanium dioxide (TiO2) nanoparticles were synthesized both on the aramid III fiber surface and in the interfacial space between the fibrils/microfibrils in supercritical carbon dioxide (scCO2) to improve the UV resistance of aramid fibers. The effects of scCO2 treatment pressure on the TiO2 structure, morphology, surface composition, thermal stability, photostability, and mechanical properties were investigated using Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, ultraviolet–visible spectroscopy, and single-fiber test. The results show that amorphous TiO2 formed on the fiber surface and the interface between fibrils/microfibrils, and decreased the photodegradation rate of the aramid III fiber. Moreover, this modification can also improve the tensile strength via treatment at low temperature and without the use of a solvent. The simple synthesis process in scCO2, which is scalable, is used for mild modifications with a green solvent, providing a promising technique for synthesizing metal dioxide on polymers.

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33

Yuxian, Li, Liu Meihong, Sun Junfeng, Wang Juan, and Tian Shuo. "Study on the effect of hybrid fiber length on tensile strength of sealing composites." Journal of Engineered Fibers and Fabrics 15 (January 2020): 155892502096822. http://dx.doi.org/10.1177/1558925020968226.

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The present paper aims at investigating the relationship between fiber length of hybrid fibers and the tensile strength of sealing composite materials. First, three kinds of fibers: cellulose fiber, aramid pulp fiber, and mineral wool fiber were sieved and their weight-average length was measured. Second, a uniform design method of U8 (43) was adopted to prepare sealing composites by the beater-addition process, and the properties of the tensile strength of the composite were examined. In the end, the relation model was concluded and verified using multi-linear regression analyzation and was further analyzed using micro mechanic theory and interfacial bonding mechanism. The results show that the regression equation can be used to estimate the tensile strength of composites with different hybrid fiber lengths. The tensile strength increased corresponding to the increase of the length of the cellulose fiber but decreased with the increase of the length of aramid pulp and mineral wool fiber. Particularly the fiber length of aramid pulp fiber had the most significant effect on tensile properties. The cases were decided by the comprehensive effects of fibers dispersion, interfacial bonding, and micromechanics.

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34

Palola, Sarianna, Jyrki Vuorinen, Jacques W. M. Noordermeer, and Essi Sarlin. "Development in Additive Methods in Aramid Fiber Surface Modification to Increase Fiber-Matrix Adhesion: A Review." Coatings 10, no. 6 (June 10, 2020): 556. http://dx.doi.org/10.3390/coatings10060556.

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This review article highlights and summarizes the recent developments in the field of surface modification methods for aramid fibers. Special focus is on methods that create a multifunctional fiber surface by incorporating nanostructures and enabling mechanical interlocking. To give a complete picture of adhesion promotion with aramids, the specific questions related to the challenges in aramid-matrix bonding are also shortly presented. The main discussion of the surface modification approaches is divided into sections according to how material is added to the fiber surface; (1) coating, (2) grafting and (3) growing. To provide a comprehensive view of the most recent developments in the field, other methods with similar outcomes, are also shortly reviewed. To conclude, future trends and insights are discussed.

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35

Yin, Lianpeng, Zongtao Zhou, Zhu Luo, Jincheng Zhong, Peng Li, Bo Yang, and Le Yang. "Reinforcing effect of aramid fibers on fatigue behavior of SBR/aramid fiber composites." Polymer Testing 80 (December 2019): 106092. http://dx.doi.org/10.1016/j.polymertesting.2019.106092.

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36

Kato, Takahisa, and Akira Magario. "The Wear of Aramid Fiber Reinforced Brake Pads: The Role of Aramid Fibers." Tribology Transactions 37, no. 3 (January 1994): 559–65. http://dx.doi.org/10.1080/10402009408983329.

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37

Zhang, Xiao Wei, Shu Peng Liu, Yu Peng Qian, and Ying Bo Zhu. "Preparation of Aramid Mica Composite Insulation Material." Advanced Materials Research 214 (February 2011): 16–20. http://dx.doi.org/10.4028/www.scientific.net/amr.214.16.

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While mica papers are used as insulation material binders and reinforcement materials are needed to enhance the mechanical strength which might reduce insulation property of mica paper materials. In this paper aramid fibers and mica flakes are mixed to make composite paper insulation, both have the high strength, heat resistance of aramid fibers and high dielectric strength, corona resistance of mica flakes. When this composite material is preparing, process of mix pulp papermaking was chosen, combined with mica flake and aramid fiber modification. Prepared composite material has properties of high tensile strength, dielectric strength, heat resistance, softness, can be used as high quality insulation.

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38

Cuong, N. K., and Z. Maekawa. "Fabrication of Aramid Fiber Knitted Fabric Reinforced Polypropylene Composites." Advanced Composites Letters 7, no. 3 (May 1998): 096369359800700. http://dx.doi.org/10.1177/096369359800700302.

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In this paper, the effects of fabrication conditions on mechanical properties of aramid fiber knitted fabric reinforced thermoplastic polypropylene composites have been investigated. Composite laminates were fabricated by variation of impregnation time and compression molding pressures. Impregnation of matrix resin into aramid fibers was identified by observing cross-sections of laminates. Tensile tests were carried out on samples cut from the laminates parallel to the wale and course directions. Tensile properties increased with increasing the impregnation time or the compression molding pressure. The tensile properties also display higher in wale direction than in course direction. SEM micrographs of fractured surfaces reveal poor adhesion between aramid fibers and polypropylene matrix.

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39

Wen, Yi Fang, Yan Nian Rui, Hong Wei Wang, and Xin Chen. "Research on Sound Absorption Properties of Aramid Micro-Perforated Composite Sound Absorbing Material." Key Engineering Materials 458 (December 2010): 14–22. http://dx.doi.org/10.4028/www.scientific.net/kem.458.14.

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Aramid fiber is one of the most promising materials used in secondary structure of the airplane, which has many merits such as low density, abrasion resistance, impact resistance, permanent flame retardance etc. Current research at home and abroad is mainly on the manufacturing process, mechanical and electrical properties of aramid fibers while the sound absorption property research is less. We prepared aramid micro-perforated composite materials according to the theory of micro-perforated absorber, in order to test and analyse sound absorption properties of micro-perforated sound-absorbing materials with different thickness, aperture, perforation ratio and combined program by using acoustic standing wave tube measurement system. Experimental results show that: the absorption effect of the Micro-perforated Panel Aramid Composite is obvious, in a certain frequency; the absorption coefficient is greatly improved. The study offers a new method for aramid fibers which could be applied in planes and cars.

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Wang, Yan, Jakub Wiener, Jiri Militky, Rajesh Mishra, and Guocheng Zhu. "Ozone Effect On the Properties of Aramid Fabric." Autex Research Journal 17, no. 2 (June 27, 2017): 164–69. http://dx.doi.org/10.1515/aut-2016-0027.

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Abstract The limitation of aramid fiber is its surface property, which results in its very poor interfacial adhesion to most of commercial resins. In order to improve the surface property of the aramid fiber, ozone treatment was carried out in this work. The aramid fabrics were evaluated in terms of surface morphology, wicking effect, tensile property, and ball bursting test. The results showed that the surface morphology of aramid fabrics did not undergo an obvious change; the wicking effect increased slightly with an increase in ozone treatment time; the tenacity and elongation of aramid fibers and fabrics did not significant change after ozone treatment, but the tenacity and elongation of aramid yarns showed significant improvement after ozone treatment, and increased with the increase of ozone treatment time; the ball bursting load and penetration displacement had a slight increase as well after ozone treatment. Therefore, ozone treatment could be one method to improve the surface property of the aramid fiber.

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41

Zhang, Quichen, Ying Liang, and Steven B. Warner. "Partial carbonization of aramid fibers." Journal of Polymer Science Part B: Polymer Physics 32, no. 13 (October 1994): 2207–20. http://dx.doi.org/10.1002/polb.1994.090321308.

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42

Yao, Jian, Junhong Jin, Emiliano Lepore, Nicola M. Pugno, Cees W. M. Bastiaansen, and Ton Peijs. "Electrospinning of p -Aramid Fibers." Macromolecular Materials and Engineering 300, no. 12 (July 21, 2015): 1238–45. http://dx.doi.org/10.1002/mame.201500130.

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43

Forsyth, D. S., S. O. Kasap, I. Wacker, and S. Yannacopoulos. "Thermal Fatigue of Composites: Ultrasonic and SEM Evaluations." Journal of Engineering Materials and Technology 116, no. 1 (January 1, 1994): 113–20. http://dx.doi.org/10.1115/1.2904246.

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Results are presented on the evaluation of thermal fatigue in three fiber reinforced polymer composites, using ultrasonic techniques and scanning electron microscopy. The composites examined were (a) continuous carbon fibers in a vinylester matrix (b) continuous aramid fibers in a vinylester matrix and (c) randomly oriented aramid fibers in a polyphenylene matrix. Specimens of these composites were subjected to thermal fatigue by thermal cycling from −25°C to 75°C. Changes in ultrasonic attenuation and velocity were monitored during thermal cycling, and scanning electron microscopy was used to qualitatively evaluate any damage. It was observed that ultrasonic attenuation is sensitive to thermal fatigue, increasing with increasing number of thermal cycles. SEM evaluations showed that the primary damage due to thermal fatigue is due to fiber-matrix debonding.

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44

Lu, Xiang Hui, Chen Liu, Jun Tian, and Yang Li. "Study of Applying Aramid Fiber Treated Insurface to EPDM Rubber Composite Materials." Applied Mechanics and Materials 446-447 (November 2013): 18–21. http://dx.doi.org/10.4028/www.scientific.net/amm.446-447.18.

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The surface of aramid fiber is very smooth and chemical inert.The adhesiveness of aramid fiber with EPDM rubber materials is not good.So the tensile strength of EPDM rubber composite materials is influenced seriously.This paper modified the surface of aramid fiber with silicon coupling agentKH-550. We test the chang of fibers in surface with the ESCA,and the result is that content of carbon decreased ,while content of nitrogen and oxygen element increased.The activity of surface of fiber has been increased. Strength of composite materials increased from 2.58MPa to 3.22 MPa . The SEM photos of samples indicate that the weight of EPDM rubber on surface of EPDM rubber is more than untreated fiber composite materials .The treating effect on aramid fiber is best when the concentration of KH-550 is 5%,5hours.

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45

Zhao, Huifang, Yinbang Zhu, and Lizheng Sha. "Study of the relationship between characteristics of aramid fibrids and mechanical property of aramid paper using DSC." e-Polymers 14, no. 2 (March 1, 2014): 139–44. http://dx.doi.org/10.1515/epoly-2013-0063.

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AbstractFiber classification of aramid fibrids was carried out using a Bauer-McNett fiber classifier, and the molecular weight and thermal properties of different sizes of aramid fibrids were determined with viscometry and differential scanning calorimetry (DSC), respectively. Aramid handsheets were made from different sizes of aramid fibrids and aramid short fibers, and the relationship between mechanical strength of aramid handsheets and thermal properties of aramid fibrids was examined. In addition, aramid papers from four different sources were also investigated to elucidate the relationship between their thermal properties and mechanical strength. It was found that aramid fibrids passing through 30-mesh screens and remaining on 50-mesh screens and aramid fibrids with narrower molecular weight distribution are suitable for the production of high-strength aramid papers. Lower crystallinity and wider molecular weight distribution are important contributors to the lower mechanical strength of domestic aramid paper when compared to that of Nomex paper.

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46

Chan, Ly, Ganchai Tanapornraweekit, and Somnuk Tangtermsirikul. "Investigation of Aramid Fibers Compared with Steel Fiber on Bending Behavior of Hybrid RC Beams." Materials Science Forum 860 (July 2016): 117–20. http://dx.doi.org/10.4028/www.scientific.net/msf.860.117.

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This paper presents an experimental study on bending behavior of aramid and steel fiber reinforced concrete (AFRC and SFRC) members. The objective is to investigate effects of two types of aramid fiber and one type of steel fiber in hybrid reinforced concrete (RC) beams. The term hybrid beam is defined as the beam with fiber reinforced concrete (FRC) cast in tension zone and normal concrete (without fiber) cast in compression zone of the beam. The diameter of aramid fiber (AF) is 0.5mm and the surface condition is twist fiber consisting of two single fibers. The fiber lengths are 30mm and 40mm for two types of aramid fiber. The diameter of steel fiber (SF) is 0.6mm and the length is 33mm with hooked ends. Four reinforced concrete (RC) beams with a dimension of 150×200×2100 mm3 were designed to undergo flexural failure. All the tested beams are with the same reinforcement ratio (0.93%), having a fiber volume fraction (Vf) of 1% for each type of fiber. One RC beam without fiber was prepared and tested as a controlled specimen. The height of the FRC tension zone at ultimate state was calculated to be 170mm. Load capacity, average and maximum crack widths of hybrid aramid and steel fiber reinforced concrete beams (HAFRCs & HSFRC) under four-point bending tests were discussed.

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Vleugels, N., W. K. Dierkes, A. Blume, L. A. E. M. Reuvekamp, and J. W. M. Noordermeer. "MAIN GOVERNING FACTORS INFLUENCING MECHANICAL PROPERTIES OF SHORT-CUT ARAMID FIBER–REINFORCED ELASTOMERS." Rubber Chemistry and Technology 92, no. 3 (July 1, 2019): 445–66. http://dx.doi.org/10.5254/rct.19.82593.

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ABSTRACT This study concerns short-cut aramid fiber reinforcement of synthetic elastomer compounds and their influence on the processability and mechanical properties. Short-fiber reinforcement of elastomers is very complex, because it depends on many mutually interacting factors: fiber concentration, fiber orientation distribution, fiber length and distribution, fiber-matrix interfacial strength, and properties of the matrix. The relationship between these influencing factors is highlighted in an S-SBR compound by design of experiments. Two 3 mm long aramid fibers were used: an epoxy-amine–coated fiber and a virgin fiber without coating. To potentially achieve a fiber–matrix interaction, the following silane coupling agents were employed: bis-(triethoxysilylpropyl)-disulfane (TESPD), bis-(triethoxysilylpropyl)-tetrasulfane (TESPT), S-3-(triethoxysilylpropyl)-octanethioate (NXT), and an alkylpolyether-mercapto-silane (Si 363), all in combination with the adhesion-activated aramid fibers and in comparison with the virgin fibers. They are compared on equimolar basis with regard to the amount of reactive ethoxy groups versus TESPD, making use of a “design of experiments” approach of the experimental setup. The outcome shows that, contrary to common assumptions, the effect of the fiber–matrix interaction is grossly overshadowed by the effects of other factors (i.e., fiber concentration and orientation) on the vulcanization system. For each mechanical property response, an optimization prediction is calculated and confirmed with an experimental run, showing, for example, a 330% potential improvement in the Young's modulus.

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48

Xing, Xiangyang, Jianzhong Pei, Chenchen Shen, Rui Li, Jiupeng Zhang, Jianyou Huang, and Dongliang Hu. "Performance and Reinforcement Mechanism of Modified Asphalt Binders with Nano-Particles, Whiskers, and Fibers." Applied Sciences 9, no. 15 (July 26, 2019): 2995. http://dx.doi.org/10.3390/app9152995.

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The asphalt binders could be modified to improve road perfo rmances by using various methods, and the reinforcement mechanisms are obviously different and quietly affect the road performances. According to the composite reinforcement theory, nano-CaCO3 particles, CaCO3 whiskers, and aramid fibers were used as reinforcements to prepare modified asphalt binders, and the conventional technical performances and dynamic shear rheometer (DSR) rheological properties were measured and investigated. In addition, scanning electron microscopy (SEM) was applied to observe the interfaces between reinforcements and asphalt matrixes and the different reinforcement mechanisms were analyzed. The test results showed that the use of nano-CaCO3 particles, CaCO3 whiskers, and aramid fibers can improve the high-temperature stability of modified asphalt binders by different reinforcement mechanisms. The nano-CaCO3 particles were still effective under high-temperature conditions and could last for a long time through the principle of dispersion enhancement. The CaCO3 whiskers segregate easily and cannot be well dispersed in asphalt binders. The aramid fibers played an important role of stress transmission and fiber reinforcement in asphalt binders, and 2 mm-aramid fibers hold the best reinforcement effects. The conclusions can provide a reference for the selection and application of modifiers in the preparation of modified asphalt in laboratory and engineering projects.

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Wu, Liwei, Wei Wang, Qian Jiang, Chunjie Xiang, and Ching-Wen Lou. "Mechanical Characterization and Impact Damage Assessment of Hybrid Three-Dimensional Five-Directional Composites." Polymers 11, no. 9 (August 24, 2019): 1395. http://dx.doi.org/10.3390/polym11091395.

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The effects of braided architecture and co-braided hybrid structure on low-velocity response of carbon-aramid hybrid three-dimensional five-directional (3D5d) braided composites were experimentally investigated in this study. Low-velocity impact was conducted on two types of hybridization and one pure carbon fiber braided reinforced composites under three velocities. Damage morphologies after low-velocity impact were detected by microscopy and ultrasonic nondestructive testing. Interior damages of composites were highly dependent on yarn type and alignment. Impact damage tolerance was introduced to evaluate the ductility of hybrid composites. Maximum impact load and toughness changed with impact velocity and constituent materials of the composites. The composite with aramid fiber as axial yarn and carbon fiber as braiding yarn showed the best impact resistance due to the synergistic effect of both materials. Wavelet transform was applied in frequency and time domain analyses to reflect the failure mode and mechanism of hybrid 3D5d braided composites. Aramid fibers were used either as axial yarns or braiding yarns, aiding in the effective decrease in the level of initial damage. In particular, when used as axial yarns, aramid fibers effectively mitigate the level of damage during damage evolution.

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50

Khakhin, L. A., A. V. Kulik, I. A. Arutyunov, S. N. Potapova, E. V. Korolev, and D. V. Svetikov. "Synthesis and Application of Aramids." Oil and Gas Technologies 129, no. 4 (2020): 3–9. http://dx.doi.org/10.32935/1815-2600-2020-129-4-3-9.

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Presented overview covers existing methods for aromatic heterocyclic polyamides (aramids) production. Aramids application areas are also covered. Aramids are used to produce light, high-strength, heat-resistant, and fire-resistant multifunctional materials. Examples are honeycomb plastics, polymer paper and high-modulus fibers. The latter capable of maintaining high mechanical properties under load at elevated temperatures. In 2018, the global market for aramids was 97,000 tonnes per year. According to the forecast, it will reach 110 thousand tons per year by 2020. Development of production of aramid fibers is important for the global industry.

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Journal articles on the topic 'Aramid fibers'

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