Latent active unit triggered crosslinking inside aramid fiber with improved transverse connection and composite properties

Lyu, Jun; Chen, Yiyang; Liu, Miaoxuan; Liu, Boya; Yang, Jialin; Liu, Yang; Liu, Xiang Yang

doi:10.1016/j.compscitech.2023.110104

Cited by 3 publications

(1 citation statement)

References 35 publications

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“…Herein, we report a scalable approach for the continuous spinning of high-performance heterocyclic aramid aerogel fibers (HAAFs) by the combination of the “ropes bind rods” reinforcement concept and the “redox responsive sol–gel transition” strategy. With benzimidazole moieties containing in the main chain, heterocyclic aramid (PABI) exhibited better processability and even higher mechanical properties as compared to its counterpart PPTA. − Importantly, taking advantage of the coordination ability of benzimidazole ligand with cobalt ions, − we realized the redox reaction induced transition between highly dynamic PABI/Co 2+ complex and kinetically stable PABI/Co 3+ complex. − With this capability, the spinning dope composed of the PABI/Co 2+ complex ensured good spinnability, while as the spinning dope was extruded into the oxidation bath, it rapidly converted into the highly stable PABI/Co 3+ complex and formed gel fibers. Such an in situ cross-linked process makes a good balance between the “static” sol–gel process of aerogel materials and the “dynamic” spinning process of fiber materials and allows precise control of the degree of cross-linking and network structure of the gel fibers by adjusting reaction conditions and parameters.…”

Section: Introductionmentioning

confidence: 99%

Strong, Tough, and Recyclable Aramid Aerogel Fibers with Homogeneous Nanoscale Structures for High-Temperature Thermal Insulation Applications

Zhang,

Liu,

Huang

et al. 2024

ACS Appl. Nano Mater.

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Aramid aerogel fibers (AAFs) have attracted tremendous attention recently because of their lightweight, temperature resistance, and flame retarding characteristics, which hold great promise in wearable thermal insulation applications. However, there is still a lack of an efficient method for the fabrication of high-performance AAFs with homogeneous nanoscale structures and optimized thermal/mechanical properties. This paper reports a scalable approach for the continuous spinning of heterocyclic AAFs (HAAFs) by the combination of the "ropes bind rods" reinforcement concept and the "redox responsive sol−gel transition" strategy. The redox reaction responsiveness of the coordination property between cobalt ions and benzimidazole ligand contained in heterocyclic aramid (PABI) is exploited as triggering for sol−gel transition in the spinning process, where the highly dynamic PABI/Co 2+ complex in spinning dope rapidly converts into a highly stable PABI/Co 3+ complex upon extruding into an oxidation bath and forms gel fibers. Incorporating a small amount of flexible benzimidazole-containing polymer further promotes the gelation of PABI/Co 2+ system and strengthens the PABI/Co 3+ cross-linked networks on the basis of a "ropes bind rods" concept on the nanoscale level, which ensures the continuous spinning of HAAFs. The resultant HAAFs demonstrated a homogeneous nanoscale porous structure thanks to the in situ constructed cross-linked networks that prevent the gel skeleton from distortion in subsequent treatment. As a result, the HAAFs show mechanical strength among the highest reported values for AAFs and excellent toughness that is superior to all previous AAFs. The AAFs also exhibit good thermal stability and flame retardancy for thermal insulation applications. The recyclability of HAAFs is finally demonstrated based on the reversible feature of metal coordination bonds. This work is expected to provide an efficient strategy for the design and scalable fabrication of aramid and other high-performance aerogel fibers.

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Section: Introductionmentioning

confidence: 99%

Strong, Tough, and Recyclable Aramid Aerogel Fibers with Homogeneous Nanoscale Structures for High-Temperature Thermal Insulation Applications

Zhang,

Liu,

Huang

et al. 2024

ACS Appl. Nano Mater.

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The effects of graphene oxide addition on low velocity impact performance of aramid fiber reinforced epoxy composites

Azimpour‐Shishevan,

Mohtadi‐Bonab,

Rahmatinejad

2023

J of Applied Polymer Sci

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In this study, the impact of incorporating graphene oxide (GO) nanoparticles into the matrix of aramid fiber reinforced polymer (AFRP) composites was investigated. The GO nanoparticles were dispersed in the AFRP matrix at three different weight percentages: 0.1%, 0.3%, and 0.5%. The fabrication of the GO dispersed AFRP nanocomposites was achieved using the vacuum assisted resin infusion molding (VARIM) method, and the AFRP plates were cut using a water jet. The sectioned specimens of the fabricated nanocomposites were subjected to low velocity impact tests. The effects of introducing GO nanoparticles at different percentages were evaluated by analyzing the contact force, deflection, maximum absorbed energy versus time and contact force versus deflection curves. Finally, the key parameters of low velocity impact, including contact force, deflection, and maximum absorbed energy, were compared for the different fabricated AFRP nanocomposites. Based on the results, the AFRP composite with 0.3 wt.% of GO nanoparticles exhibited the best performance under low velocity impact loading conditions. However, the agglomeration of nanoparticles became a significant challenge when higher percentages of GO nanoparticles were added to the composite structure. The findings highlight the importance of determining the optimal percentage of nano materials for incorporation into composite structures.

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Effects of oxidation‐induced aggregation structure transformation of aramid fiber on interfacial adhesion of epoxy resin

Li,

Liu,

et al. 2024

J of Applied Polymer Sci

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The large‐scale pretreatment and efficient surface activation of aramid fibers (AFs) before composite fabrication remains a major challenge. In this study, we developed a heat treatment–induced surface modification method to change the reactive groups on AFs. Results indicated that the O/C ratio and the number of ester groups on the AFs as well as the surface morphology of the AFs could be flexibly controlled using the heat treatment–induced surface modification method. Furthermore, the surface oxidation mechanism of the AFs changed from point oxidation to surface oxidation during heat treatment. As the heat‐treatment time increased, the crystallinity and tensile strength of the AF monofilament considerably increased. An optimal heat‐treatment time of 30 min was provided considering that long‐time heating (>30 min) would destroy the surface molecular chains. Under this optimal heat‐treatment time, the number of ester groups reached the maximum, which enhanced the reactivity of the AFs in the epoxy resin matrix. The interfacial shear strength between the AFs treated for 30 min and epoxy resin microdroplet increased by 12.64%, reaching as high as 18.17 MPa. Moreover, the contact angle between the AF monofilament and epoxy resin droplet reached a minimum value of 54.7°. Furthermore, the thickness of the interfacial bond layer between the AFs and epoxy resin reached 50–60 nm. These results provide effective theoretical guidance for the large‐scale application of AFs in composite materials.

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Latent active unit triggered crosslinking inside aramid fiber with improved transverse connection and composite properties

Cited by 3 publications

References 35 publications

Strong, Tough, and Recyclable Aramid Aerogel Fibers with Homogeneous Nanoscale Structures for High-Temperature Thermal Insulation Applications

Strong, Tough, and Recyclable Aramid Aerogel Fibers with Homogeneous Nanoscale Structures for High-Temperature Thermal Insulation Applications

The effects of graphene oxide addition on low velocity impact performance of aramid fiber reinforced epoxy composites

Effects of oxidation‐induced aggregation structure transformation of aramid fiber on interfacial adhesion of epoxy resin

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