The Experts below are selected from a list of 1893 Experts worldwide ranked by ideXlab platform
Heping Zhang - One of the best experts on this subject based on the ideXlab platform.
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flexible silica aerogel composites strengthened with Aramid Fibers and their thermal behavior
Materials & Design, 2016Co-Authors: Lunlun Gong, Xudong Cheng, Heping ZhangAbstract:Abstract To meet the flexibility of some practical applications, Aramid fiber reinforced silica aerogel composites (AF/aerogels) were successfully prepared, which possessed low density, remarkable flexibility and excellent thermal insulation properties. The microstructure of the AF/aerogels showed that the Aramid Fibers were inlaid in the aerogel matrix acting as the supporting skeleton, which established the foundation of mechanical properties. Three point bending indicated that improvement in flexibility could be achieved by ~ 5% fiber content without compromising the thermal insulation properties. As the fiber content increased, the density monotonously decreased to 0.142 g·cm − 3 while the thermal conductivity increased slightly with ranging between 0.0221–0.0235 W·m − 1 ·K − 1 . The hot plate experiments indicated the transient thermal transfer was similar to one-dimensional heat transfer and the heat transfer characteristics were further analyzed in which a simple method to estimate the thermal conductivity was established according to the Fourier's law. TG-DSC analysis revealed that the thermal stability was up to approximately 285 °C which was mainly depended on the thermostability of pure silica aerogels. All these characteristics indicated that the as-prepared AF/aerogels were excellent thermal insulation materials and have great practical application prospects.
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Aramid Fibers reinforced silica aerogel composites with low thermal conductivity and improved mechanical performance
Composites Part A: Applied Science and Manufacturing, 2016Co-Authors: Zhi Li, Xiaojing Shi, Lunlun Gong, Song He, Xudong Cheng, Heping ZhangAbstract:Aramid Fibers reinforced silica aerogel composites (AF/aerogels) for thermal insulation were prepared successfully under ambient pressure drying. The microstructure showed that the Aramid Fibers were inlaid in the aerogel matrix, acting as the supporting skeletons, to strengthen the aerogel matrix. FTIR revealed AF/aerogels was physical combination between Aramid Fibers and aerogel matrix without chemical bonds. The as prepared AF/aerogels possessed extremely low thermal conductivity of 0.0227 ± 0.0007 W m-1K-1with the fiber content ranging from 1.5% to 6.6%. Due to the softness, low density and remarkable mechanical strength of Aramid Fibers and the layered structure of the fiber distribution, the AF/aerogels presented nice elasticity and flexibility. TG-DSC indicated the thermal stability reaching approximately 290 °C, can meet the general usage conditions, which was mainly depended on the pure silica aerogels. From mentioned above, AF/aerogels present huge application prospects in heat preservation field, especially in piping insulation.
Aijuan Gu - One of the best experts on this subject based on the ideXlab platform.
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building unique surface structure on Aramid Fibers through a green layer by layer self assembly technique to develop new high performance Fibers with greatly improved surface activity thermal resistance mechanical properties and uv resistance
Applied Surface Science, 2017Co-Authors: Lifang Zhou, Aijuan Gu, Qingbao Guan, Li Yuan, Guozheng LiangAbstract:Abstract Combining green preparation and high performance is becoming the direction of sustainable development of materials. How to simultaneously overcome the two bottlenecks (poor surface activity and UV resistance) of Aramid Fibers (AFs) while improving thermal and mechanical properties through a green process is still an interesting issue with big challenge. Herein, new AFs (BL-AFs) were prepared by alternately self-assembling SiO2 and MgAlFe layered double hydroxide (LDH) on surfaces of AFs, successively, through a green layer-by-layer (LBL) self-assembly technique without using high temperature and organic solvent. The structures and properties of BL-AFs were systematically studied, which are controllable by adjusting the number of self-assembly cycle. The new Fibers with three or more self-assembly cycles have remarkably improved surface activity, thermal resistance, mechanical properties and UV resistance compared with AFs. Typically, with three self-assembly cycles, the initial degradation temperature and char yield of the new fiber (3BL-AF) are as high as 552.9 °C and 81.2%, about 92 °C and 25.2% higher than those of AF, respectively; after 168 h-UV irradiation, the retention of tensile performances of 3BL-AF fiber is as high as 91–95%, about 29–14% higher than that of AF, showing the best overall performances among all modified AFs prepared using a green technique reported so far. The origin behind the attractive performances of BL-AFs is revealed through correlating with structures of original and modified Fibers. The excellent comprehensive properties of BL-AFs demonstrate that the green method provided in this study is facile and effective to completely solve the bottlenecks of Aramid Fibers, and developing higher performance organic Fibers.
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A novel strategy of fabricating high performance UV-resistant Aramid Fibers with simultaneously improved surface activity, thermal and mechanical properties through building polydopamine and graphene oxide bi-layer coatings
Chemical Engineering Journal, 2017Co-Authors: Jiaojiao Zhu, Qingbao Guan, Li Yuan, Guozheng Liang, Aijuan GuAbstract:Using facile strategy to prepare UV resistant Aramid Fibers (KFs) with high surface activity, thermal and mechanical properties is the most important and urgent issue of sustainably developing high performance organic Fibers. Herein, a novel two-step strategy has been built to prepare new KF (KF-PDA-GO) with remarkably improved integrated performances by forming polydopamine (PDA) and graphene oxide (GO) bi-layer coatings on the surfaces of KFs. Orthogonal tests based on three factors and three levels were designed and carried out to systematically study the influences of dopamine (DA) concentration, GO concentration and reaction temperature on the structure and performances of KF-PDA-GO Fibers. Results show that the reaction temperature is the decisive factor for both surface active and UV-resistance. All KF-PDA-GO Fibers not only have greatly improved surface activity and UV resistance, overcoming the two intractable disadvantages of KFs, but also show outstanding thermal resistance and higher tensile properties including tensile strength, modulus, elongation and break energy. For the new fiber (KF-PDA-GO3) prepared with the optimum conditions, its surface free energy increases 54%, meanwhile the retention of tensile strength after 168 h-UV irradiation is as high as 93.4%, almost the best value among the latest modified KF Fibers reported. Different failure modes are found between original and modified KF Fibers through intensively discussing the morphological and chemical structures of Fibers. This investigation provides a novel and facile method to develop new KF Fibers with higher integrated performances, especially outstanding surface activity, UV resistance, thermal and mechanical properties.
Henry Angelo Sodano - One of the best experts on this subject based on the ideXlab platform.
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enhanced interfacial strength of Aramid fiber reinforced composites through adsorbed Aramid nanofiber coatings
Composites Science and Technology, 2019Co-Authors: Jalal Nasser, Jiajun Lin, Kelsey Steinke, Henry Angelo SodanoAbstract:Abstract Aramid Fibers are well-known for their excellent tensile properties and low density but are limited in composite applications due to their inert surface which leads to poor interfacial properties. One method that has shown promise in recent years is the application of nanoscale reinforcements to the surface of the Fibers to improve mechanical interaction with the matrix. With Aramid Fibers, it is ideal to perform an interfacial reinforcement utilizing the dense hydrogen bonding which is responsible for the Fibers strength. Here, it is demonstrated that recently developed Aramid nanoFibers (ANFs) can adsorb onto the surface of macroscale Aramid Fibers to enhance the interfacial properties through mechanical interlocking with the matrix. A simple and rapid dip-coating process is used to deposit the ANFs on the Aramid fiber surface. These ANFs bond with the fiber through physisorption and hydrogen bonding, yielding a 70.27% increase in interfacial shear strength and a 25.6% increase in short beam shear strength in composites prepared by dip-coating unidirectional tape into a solution of ANFs. Notably, the interfacial gains are made while fully preserving the strength of the Aramid fiber following the treatment, therefore ensuring in-plane properties of the composite are maintained. This work shows that the introduction of an ANF interphase may present a novel and convenient method to improve the interfacial strength of Aramid reinforced composites, enabling cost-effective and simplified production of stronger structural materials.
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high strength fiber reinforced composites with surface fibrilized Aramid Fibers
Journal of Applied Physics, 2018Co-Authors: Jalal Nasser, Jiajun Lin, Henry Angelo SodanoAbstract:Debonding of the fiber-matrix interface is a common issue in composites, especially for Aramid fiber reinforced composites due to their smooth and inert surface. Here, a novel surface treatment is developed for Aramid Fibers in order to enhance the interfacial properties in composites while preserving the fiber's tensile strength. The fibrilization approach follows the recent work on the Aramid nanoFibers and uses a solution of potassium hydroxide and dimethyl sulfoxide at room temperature. This process is performed to exfoliate the surface fibrils such that a pseudo-wiskerized fiber is prepared, which provides mechanical interlocking with the matrix. The surface bound fibrils also contain increased polar functional groups, which additionally provides improved wetting due to the enhanced compatibility of the fiber with the matrix as well as offering reactive sites to allow covalent bonding with the reactive thermosets such as epoxy. It is shown that the surface fibrilized Fibers possess an 128% improved interfacial shear strength with an epoxy matrix, as well as a 62% increased short beam strength, compared with untreated fiber reinforced composites. The tensile strength of the treated Fibers is demonstrated to be preserved, ensuring a significant improvement in the common failure modes without a degradation of in-plane properties. The results indicate the potential of this treatment as a simple, fast, and cost-effective method to improve not only the interface in the Aramid fiber reinforced polymer matrix composites but also the bulk laminated composite.Debonding of the fiber-matrix interface is a common issue in composites, especially for Aramid fiber reinforced composites due to their smooth and inert surface. Here, a novel surface treatment is developed for Aramid Fibers in order to enhance the interfacial properties in composites while preserving the fiber's tensile strength. The fibrilization approach follows the recent work on the Aramid nanoFibers and uses a solution of potassium hydroxide and dimethyl sulfoxide at room temperature. This process is performed to exfoliate the surface fibrils such that a pseudo-wiskerized fiber is prepared, which provides mechanical interlocking with the matrix. The surface bound fibrils also contain increased polar functional groups, which additionally provides improved wetting due to the enhanced compatibility of the fiber with the matrix as well as offering reactive sites to allow covalent bonding with the reactive thermosets such as epoxy. It is shown that the surface fibrilized Fibers possess an 128% improved i...
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Aramid nanoFibers for multiscale fiber reinforcement of polymer composites
Composites Science and Technology, 2018Co-Authors: Brendan A. Patterson, Angelica Okorom, Mohammad H. Malakooti, Jiajun Lin, Henry Angelo SodanoAbstract:While Aramid Fibers have been innovative for ballistic protection because of their high energy absorption, minimal usage has been applied to continuous fiber reinforced polymer (CFRP) composites in structural applications. One of the challenges with Aramid Fibers results from their processing, which yields smooth and chemically inert surfaces that limit the ability of the Fibers to adhere to polymeric matrices. Here, it is shown that Aramid nanoFibers can adhere to the surface of macroscale Aramid reinforcements to improve the strength of the composite interface and reinforce the matrix as well. Aramid nanoFibers are formed through the dissolution of Aramid Fibers followed by isolation and dispersion into an epoxy matrix. When employed in CFRP, Aramid nanoFibers prove to be effective reinforcement agents through improvement in both matrix properties as well as modifying the interfacial shear strength, which leads to improved interlaminar shear strength and fracture toughness. The interface enhancements are attributed to hydrogen bonding and π-π coordination between the Aramid nanoFibers and the macro Fibers providing improved transfer load from the fiber to the matrix. This work demonstrates that Aramid nanoFibers may provide the robust mechanical properties that are necessary for structural applications while utilizing a cost-effective and convenient nanoscale building block.
Guozheng Liang - One of the best experts on this subject based on the ideXlab platform.
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building unique surface structure on Aramid Fibers through a green layer by layer self assembly technique to develop new high performance Fibers with greatly improved surface activity thermal resistance mechanical properties and uv resistance
Applied Surface Science, 2017Co-Authors: Lifang Zhou, Aijuan Gu, Qingbao Guan, Li Yuan, Guozheng LiangAbstract:Abstract Combining green preparation and high performance is becoming the direction of sustainable development of materials. How to simultaneously overcome the two bottlenecks (poor surface activity and UV resistance) of Aramid Fibers (AFs) while improving thermal and mechanical properties through a green process is still an interesting issue with big challenge. Herein, new AFs (BL-AFs) were prepared by alternately self-assembling SiO2 and MgAlFe layered double hydroxide (LDH) on surfaces of AFs, successively, through a green layer-by-layer (LBL) self-assembly technique without using high temperature and organic solvent. The structures and properties of BL-AFs were systematically studied, which are controllable by adjusting the number of self-assembly cycle. The new Fibers with three or more self-assembly cycles have remarkably improved surface activity, thermal resistance, mechanical properties and UV resistance compared with AFs. Typically, with three self-assembly cycles, the initial degradation temperature and char yield of the new fiber (3BL-AF) are as high as 552.9 °C and 81.2%, about 92 °C and 25.2% higher than those of AF, respectively; after 168 h-UV irradiation, the retention of tensile performances of 3BL-AF fiber is as high as 91–95%, about 29–14% higher than that of AF, showing the best overall performances among all modified AFs prepared using a green technique reported so far. The origin behind the attractive performances of BL-AFs is revealed through correlating with structures of original and modified Fibers. The excellent comprehensive properties of BL-AFs demonstrate that the green method provided in this study is facile and effective to completely solve the bottlenecks of Aramid Fibers, and developing higher performance organic Fibers.
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A novel strategy of fabricating high performance UV-resistant Aramid Fibers with simultaneously improved surface activity, thermal and mechanical properties through building polydopamine and graphene oxide bi-layer coatings
Chemical Engineering Journal, 2017Co-Authors: Jiaojiao Zhu, Qingbao Guan, Li Yuan, Guozheng Liang, Aijuan GuAbstract:Using facile strategy to prepare UV resistant Aramid Fibers (KFs) with high surface activity, thermal and mechanical properties is the most important and urgent issue of sustainably developing high performance organic Fibers. Herein, a novel two-step strategy has been built to prepare new KF (KF-PDA-GO) with remarkably improved integrated performances by forming polydopamine (PDA) and graphene oxide (GO) bi-layer coatings on the surfaces of KFs. Orthogonal tests based on three factors and three levels were designed and carried out to systematically study the influences of dopamine (DA) concentration, GO concentration and reaction temperature on the structure and performances of KF-PDA-GO Fibers. Results show that the reaction temperature is the decisive factor for both surface active and UV-resistance. All KF-PDA-GO Fibers not only have greatly improved surface activity and UV resistance, overcoming the two intractable disadvantages of KFs, but also show outstanding thermal resistance and higher tensile properties including tensile strength, modulus, elongation and break energy. For the new fiber (KF-PDA-GO3) prepared with the optimum conditions, its surface free energy increases 54%, meanwhile the retention of tensile strength after 168 h-UV irradiation is as high as 93.4%, almost the best value among the latest modified KF Fibers reported. Different failure modes are found between original and modified KF Fibers through intensively discussing the morphological and chemical structures of Fibers. This investigation provides a novel and facile method to develop new KF Fibers with higher integrated performances, especially outstanding surface activity, UV resistance, thermal and mechanical properties.
Liqun Zhang - One of the best experts on this subject based on the ideXlab platform.
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surface modification of Aramid Fibers by catechol polyamine codeposition followed by silane grafting for enhanced interfacial adhesion to rubber matrix
Industrial & Engineering Chemistry Research, 2016Co-Authors: Lei Wang, Nan Ying Ning, Wencai Wang, Rina Sa, Ming Tian, Liqun ZhangAbstract:In this work, we develop a modified mussel-inspired method to enhance interfacial adhesion of Aramid fiber to a rubber matrix. Through a simple dip-coating procedure, catechol and polyamine could initially codeposit as a poly(catechol-polyamine) (PCPA) coating on the surface of the Aramid fiber. Then, the PCPA layer could be further grafted with silane coupling agent γ-(glycidyloxypropyltrimethoxysilane) (GPTMS). Results indicated that GPTMS was successfully grafted onto the Aramid fiber surface via the bridging of the PCPA layer. The interfacial adhesion between the Aramid Fibers and the rubber matrix was improved compared to that achieved by polydopamine in our previous study. In addition, this method is more applicable to the rubber industry than polydopamine coating because of its cost-effectiveness and short reaction time.
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surface silverized meta Aramid Fibers prepared by bio inspired poly dopamine functionalization
ACS Applied Materials & Interfaces, 2013Co-Authors: Wencai Wang, Ming Tian, Li Liu, Hua Zou, Xiuying Zhao, Liqun ZhangAbstract:A facile method was developed to fabricate highly electrically conductive Aramid Fibers. The immobilization of silver nanoparticles on the surface of polymetaphenylene isophthamide (PMIA) Fibers was carried out by the functionalization of the PMIA Fibers with poly(dopamine), followed by electroless silver plating. The poly(dopamine) (PDA) layer was deposited on the PMIA surface by simply dipping the PMIA substrate into an alkaline dopamine solution. The silver ions can be chemically bound to the catechol and indole functional groups in PDA. The silver ions were reduced into silver nanoparticles by using glucose as the reducing agent, resulting in a distinct silver layer on the PMIA surface. The obtained silver deposit was homogeneous and compact. The chemical composition of the modified PMIA Fibers was studied by X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDS), and the crystalline structure of the silver-coated PMIA Fibers was characterized by powder X-ray diffraction...