11 results on '"Qu Chunyan"'
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2. Preparation of waterborne polyimide‐modified epoxy resin with high thermal properties and adhesion properties.
- Author
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Xing, Hao, Mao, Yanyu, Yang, Yang, Qu, Chunyan, Wang, Dezhi, Fan, Xupeng, Zhao, Liwei, Zhou, Dongpeng, and Liu, Changwei
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POLYIMIDES ,EPOXY resins ,THERMAL properties ,EPOXY coatings ,SALTWATER solutions ,GLASS transition temperature ,STRENGTH of materials - Abstract
In response to the theme of environmental protection and green development in the world in the recent years, waterborne epoxy resin has received more and more attention. Waterborne epoxy resin has lower toxicity, but its low toughness limits the application range of waterborne epoxy resin. Here, we first proposed a method of toughening waterborne epoxy resin with aqueous polyamide salt solution. In this article, a series of waterborne polyamic acid salts is used as modification polymer to improve the high‐temperature resistance and other properties of waterborne epoxy resins by copolymerization modification. Waterborne polyamic acid salt is dispersed uniformly in the epoxy resin. After curing, by compared with the pure epoxy resin, a semi‐interpenetrating network is formed, the cross‐linking density and the high‐temperature resistance of the material are increased, and the glass transition temperature increases from 105°C to 116°C. The storage modulus at 300°C increases from 6.15 to 15.76 MPa. Thermogravimetric Analysis results reveal that the corresponding temperatures of 5% and 10% weight loss increase from 403°C and 419°C to 415°C and 435°C, respectively. At the same time, the toughness of the imide chain segment and polar groups lead to the improved adhesion of the epoxy system, the peeling strength increase from 0.51 to 1.24 N cm−1, and the lap shear strength at high temperature (100°C) increase from 0.58 to 16.97 MPa. The water absorption decreases from 1.51% to 0.66%. The developed waterborne epoxy resin is expected to be used as a high‐temperature waterborne epoxy coating in high‐temperature coatings and other applications. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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3. In-Situ self-encapsulated flexible multi-layered poly (imide siloxane) copolymer film with resistance to atomic oxygen
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Tang Yao, Chang Jiaying, Qu Chunyan, Yang Haidong, Xiao Wanbao, Wang De-zhi, Li Liaoliao, Fan Xupeng, Liu Zhongliang, Zhao Daoxiang, Liu Changwei, and Zheng Shuai
- Subjects
Thermogravimetric analysis ,Materials science ,Scanning electron microscope ,Composite number ,02 engineering and technology ,Dynamic mechanical analysis ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Flexible electronics ,0104 chemical sciences ,chemistry.chemical_compound ,X-ray photoelectron spectroscopy ,chemistry ,Mechanics of Materials ,Siloxane ,Materials Chemistry ,General Materials Science ,Composite material ,0210 nano-technology ,Polyimide - Abstract
Silvered polyimide films, synthesized by an in-situ self-assembly method, find many applications in the fields of electronics and aerospace materials. In this work, polyimide/siloxanes were introduced into silvered PI films by an in-situ self-assembly process, which were resistant to atomic oxygen. Their atomic oxygen (AO) resistance behaviors were studied, wherein the mass loss of 20% Si-poly(amide acid salt) PAAS film was 30 ug cm−2 after exposure to AO fluence of 1.33 × 1020 O (10.5 h) and 190 ug cm−2 even after 42 h. Additionally, the volume resistivity value of the flexible PI/Ag composite film was 9.9 Ω cm−1 after 260 cycles of bending. The peel strength of PI/Ag/PI composite film was seven times more than that of the coated one (0.7 N cm-1 to 0.1 N cm-1). Moreover, (Dynamic Mechanical Analysis) DMA and (Thermogravimetric Analysis) TGA data also show that the introduction of self-encapsulating PAAS can not only increase the interlayer strength but maintain the performance of PI film. X-ray photoelectron spectroscopy, scanning electron microscopy, and atomic force microscopy were also employed to test the relative AO resistance behaviors. Thus, the silvered poly(siloxane amic acid) Si-PI composite films have AO resistance, high peel strength and alternating conductivity/ insulative effect, and hence can serve as a flexible printed circuit board for potential applications in low earth orbit.
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- 2020
4. Novel allyl and propenyl monomers for modification of the bismaleimide resins, with excellent dielectric properties and high glass transition temperatures.
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Qu, Chunyan, Chang, Jiaying, Liu, Changwei, Wang, Dezhi, Xiao, Wanbao, Su, Kai, Feng, Hao, Li, Liaoliao, Zhao, Daoxiang, Zheng, Shuai, Tang, Yao, Fan, Xupeng, and Jing, Jiaqi
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GLASS transition temperature , *NUCLEAR magnetic resonance spectroscopy , *DIELECTRIC properties , *BISPHENOLS , *MONOMERS , *BISPHENOL A , *DYNAMIC mechanical analysis , *FOURIER transform infrared spectroscopy - Abstract
Two new monomers were prepared by the reaction of 2-allylphenol and 4,4′-biphenyldicarbonyl chloride under different reaction conditions. The monomers were characterized by Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. The curing processes of N, N -4,4′-bismaleimidodiphenylmethyene with 4,4′-bis(2-allylphenyl) biphenyldicarbonylate (BABC) and 4,4′-bis(2-propenylphenyl benzoate) ether (BPBE) were studied by rheological analysis and differential scanning calorimetry. Melting points of two monomers, BABC and BPBE, are 64°C and 121°C, respectively. The ABMI [4,4′-bis(2-allylphenyl)biphenyl bismaleimide] and PBMI [4,4′-bis(2-propenylphenyl)biphenyl bismaleimide] resins showed exothermic peaks at 233°C and 204°C, respectively. The measured melting points are significantly lower than that of the traditional bismaleimide resin which is modified by allyl bisphenol A. Dynamic mechanical analysis of the materials showed glass transition temperatures of ABMI and PBMI to be in the range of 213–258°C and 302–339°C, respectively. Thermogravimetric analysis of the cured resins showed 5% weight loss for ABMI and PMBI at 437°C and 428°C, along with char residues of 35.6–39.5%, respectively, at 800°C under nitrogen atmosphere. Furthermore, dielectric constants of propenyl-modified resins were lower (2.46–3.10) with dissipation factors of 0.0034–0.0036, compared with those of allyl bisphenol A resins. [ABSTRACT FROM AUTHOR]
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- 2020
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5. Preparation and characterization of high-performance polyamic acid salt hydrogel in aqueous solution.
- Author
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Zhou, Haoran, Zheng, Shuai, Liu, Changwei, Qu, Chunyan, Wang, Yiying, Xiao, Wanbao, Li, Hongfeng, Zhao, Daoxiang, and Chang, Jiaying
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SALTWATER solutions ,HYDROGELS ,AQUEOUS solutions ,INFRARED spectroscopy ,PHENYLENEDIAMINES ,ORGANIC solvents - Abstract
Herein, we report an easy-to-prepare polyamic acid salt (PAAS) hydrogel with multiple functionalities including rapid self-healing, stimuli-responsive properties, and conductivity. This study describes a method for synthesizing PAAS hydrogel in aqueous solution. Phenylenediamine and 3,3′,4,4′-biphenyltetracarboxylic dianhydride were used to prepare a hydrogel with a fully aromatic backbone via gradual polymerization. It is possible to use the gel in the field of biomaterials in the absence of organic solvents. The prepared hydrogel was characterized using Fourier-transform infrared spectroscopy and dynamic rheometry. The gel has good toughness and the storage modulus and tensile stress are, respectively, about 0.25 and 0.45 MPa. Our study may pave the way for the manufacture of PAAS hydrogel, which may promote the development of hydrogel materials. [ABSTRACT FROM AUTHOR]
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- 2019
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6. Synthesis, characterization, and properties of thermoplastic polyimides derived from 4,4’-(hexafluoroisopropylidene)diphthalic anhydride in diethylene glycol dimethyl ether.
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Ma, Liqun, Zhu, Guangyu, Liu, Changwei, Qu, Chunyan, Jia, Hongge, Li, Liaoliao, Cao, Zhibo, and Zhang, Hui
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POLYIMIDES ,ANHYDRIDES ,THERMAL stability ,MOLECULAR weights ,THERMAL properties - Abstract
By regulating the order of monomer addition, four kinds of copolymer polyimides (PIs) were prepared using diethylene glycol dimethyl ether (DEGDE) and N,N-dimethylacetamide (DMAc) as the solvents. The molecular weights of polyamide acids (PAAs) ranged from 3.8 × 10
5 to 9.2 × 105 . All of the films displayed high glass transition temperatures (Tg s) ranging from 313°C to 346°C. The polymer films show excellent thermal stabilities with 5% weight loss at temperatures of 505–524°C and char yields at 800°C were as high as 55% under nitrogen. The peel strengths of flexible copper (Cu) clads were in the range from 0.337 N cm−1 to 0.598 N cm−1 . Compared to the molecular weight and peel strength of fresh PAA, those of PAAs prepared using DMAc significantly decreased after storage for 3 months at 0°C. However, when DEGDE was used as the solvent, the molecular weights of the PAAs and the thermal properties of the PIs were maintained after long storage time. [ABSTRACT FROM AUTHOR]- Published
- 2018
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7. Preparation and magnetic and thermal properties of flexible polyimide films with iron nitrophthalocyanine-coated magnetite microspheres.
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Liu, Changwei, Qu, Chunyan, Wang, Dezhi, Yu, Weimiao, Xiao, Wanbao, and Su, Kai
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POLYIMIDE films , *SURFACE coatings , *MAGNETIC materials , *SCANNING electron microscopy , *X-ray diffraction , *NANOPARTICLES , *THERMAL properties - Abstract
To effectively utilize the one-step solvent–thermal route to prepare iron (Fe)–nitrophthalocyanine/magnetite (Fe3O4) hybrid microspheres, we have developed a novel series of flexible Fe3O4/Fe-phthalocyanine (FePc)/polyimide (PI) composite films with various Fe3O4/FePc nanoparticle loadings (15, 27, and 40 wt%) and imidized at different temperatures (200°C and 300°C). The morphology and structure of the composite films were monitored using scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction, and the hybrid microspheres were found uniformly dispersed in the polymer matrices without any agglomeration. Mechanical and thermal properties of the composites were also investigated. The observed results indicated enhanced thermal stabilities, dramatically increased tensile modulus, and increased glass transition temperatures of the composite films, with the increment in the content of inorganic nanoparticles. Besides that, the Fe3O4/FePc/PI magnetic films showed higher saturation magnetization (24.33 emu g−1, 27 wt% Fe3O4/FePc loading) with high-temperature treatment compared with that of the Fe3O4/PI film (18.79 emu g−1, 27 wt% Fe3O4 loading). It proved to be an effective way to prevent Fe3O4 nanoparticles from oxidizing by coating the nanoparticles with organic layer. The flexible composite films can easily be moved under a relatively low magnetic field, indicating them to be the high-performance absorbing materials in potential applications. [ABSTRACT FROM AUTHOR]
- Published
- 2016
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8. Simple and environmentally friendly approach for preparing high-performance polyimide precursor hydrogel with fully aromatic structures for strain sensor.
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Zhou, Haoran, Zheng, Shuai, Qu, Chunyan, Wang, Dezhi, Liu, Changwei, Wang, Yiying, Fan, Xupeng, Xiao, Wanbao, Li, Hongfeng, Zhao, Daoxiang, Chang, Jiaying, Chen, Chunhai, and Zhao, Xiaogang
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STRAIN sensors , *POLYIMIDES , *HYDROGELS , *MOTION detectors , *RAW materials - Abstract
• PAAS hydrogel was prepared through an environmentally friendly method. • PAAS hydrogel owns self-healing, stimulus responsive etc. properties. • PAAS hydrogel is highly suitable for use as sensitive strain sensors. The development of wearable devices, soft robots, and electronic skin requires strain sensors that integrate multiple functionalities, such as being stretchable, self-healing, and biocompatible. In this work, we prepared a fully aromatic polyamic acid salt (PAAs) hydrogel using a novel and simple approach. This study describes an environmentally friendly and green synthetic method for synthesizing. The obtained PAAs hydrogel exhibits excellent stretch ability and has an elongation rate of about 1350%. It can also rapidly complete self-healing and return to the original mechanical strength without needing any external stimuli. In addition, the PAAs hydrogel has excellent temperature responsiveness. When used as a strain sensor, the PAAs hydrogel has a sensitive electrical resistance response even after 200 cycles and adhesiveness to various surfaces, especially human skin. To the best of our knowledge, this is the first time to prepare a high-performance polyimide (PI) precursor hydrogel that can be used as a raw material for PI aerogel. Because of its superb overall performance, low preparation cost, efficient preparation, and environmentally friendliness, the PAAs hydrogel is highly suitable for use as sensitive strain sensors for applications in motion detection. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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9. A combination of "Inner - Outer skeleton" strategy to improve the mechanical properties and heat resistance of polyimide composite aerogels as composite sandwich structures for space vehicles.
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Sun, Qi, Tian, Kun, Liu, Sihan, Zhu, Qing, Zheng, Shuai, Chen, Jing, Wang, Liping, Cheng, Si, Fan, Zhen, Fan, Xupeng, Wang, Dezhi, Qu, Chunyan, and Liu, Changwei
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SANDWICH construction (Materials) , *COMPOSITE structures , *SPACE vehicles , *THERMAL insulation , *FATIGUE limit , *AEROGELS - Abstract
Low density aerogels with high fatigue resistance are widely used in the manufacturing of core material structures in aircraft fuselage to be able to tolerate the extreme environment of aerospace. However, most organic aerogel materials have poor energy absorption of external impact forces, and are prone to irreversible deformation, such as contracture and collapse in the process of long-term service. In order to solve this problem, a new type of thermosetting-thermoplastic polyimide composite aerogel was prepared, with its microstructure presenting the coexistence of the inner and outer skeletons. The intermolecular forces promoted the assembly of the soft thermoplastic layer and the strong thermosetting layer in the thermodynamic process with 4.63–6.55 μm range. The hard-soft layer structure improved the compressive and the shear load bearing capacities by bending of the panel (Compressive modulus is 1.60 MPa–3.52 MPa, tensile modulus is 1.04 MPa–1.45 MPa). Its permanent degradation less than 1.5 % after 500 cycles at 30 % strain. C–CPIAs also exhibited excellent heat resistance and thermal insulation performances, with a T 5% value of 612 °C (C-CPIA-2), T g of 458 °C (C-CPIA-3). The sandwich materials can be used as outer protective composite material of aircraft fuselage for future deep space missions. [ABSTRACT FROM AUTHOR]
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- 2024
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10. High-strength and high-temperature-resistant multilayer interconnected polyimide paper derived from anisotropic aerogel via a hot-extrusion strategy for aerospace applications.
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Jia, Tingting, Chen, Hao, Fan, Zhen, Xu, Huikang, Huang, Jinlong, Wang, Pengtao, Xing, Hao, Jia, He, Fan, Xupeng, Zhou, Haoran, Wang, Dezhi, Qu, Chunyan, Gohy, Jean-François, and Liu, Changwei
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POLYIMIDES , *AEROGELS , *CORPORATE bonds , *TECHNOLOGICAL innovations , *THERMAL stability , *THERMAL properties - Abstract
An anisotropic aerogel hot-extrusion strategy is designed to convert polyimide aerogels into aerogel-based paper. The multilayer interconnected aerogel-based paper exhibits excellent thermal stability and mechanical properties, and the mechanical properties remain great at high temperatures. This aerogel-based paper has huge application potential in the aerospace field. [Display omitted] • Multi-layer interconnected aerogel based paper was successfully prepared by anisotropic aerogel hot extrusion strategy. • Aerogel-based papers exhibit excellent thermal stability and stable mechanical properties (PI-1: 216.28 MPa at 25 °C). • The tensile strength of PI-1 was 3 times that of commercial polyimide paper and 24 times that of aramid paper at 400 °C. • Aerogel-based paper maintain stable mechanical property after 5000 cycles. The continuous improvement of papermaking technology has attracted widespread attention. However, the prevention of high-temperature decomposition and a subsequent decline in mechanical strength is still a significant challenge with current papermaking technology. Herein, a newly developed multilayer interconnected polyimide aerogel-based paper was successfully prepared via an anisotropic aerogel hot-extrusion strategy. Precursor solutions of highly rigid benzimidazole units containing intermolecular hydrogen bonds and linear rod-like benzimide units were first prepared. Anisotropic precursor polyimide (PAAS) aerogels with a thickness of 3 mm were then manufactured by unidirectional freeze-drying. Then, aerogel-based papers with a thickness of 40 μm and microstructure multilayer interconnected properties were obtained by a hot extrusion strategy and a thermal imidization process. This polyimide structural paper exhibited excellent thermal and mechanical properties. Through the design of micro and macro structures, the tensile strength of the aerogel-based paper was much higher than that of commercial paper at both room temperature and 400 ℃. This aerogel-based paper also exhibited high-temperature cycle stability, high flexibility, and good stretchable bending properties. The successful preparation of this aerogel-based paper demonstrates the feasibility of the hot extrusion strategy. This work provides a new papermaking technology method and broadens the application field of paper. [ABSTRACT FROM AUTHOR]
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- 2023
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11. Anisotropic all-aromatic polyimide aerogels with robust and high-temperature stable properties for flexible thermal protection.
- Author
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Ma, Shengqi, Wang, Chengyang, Cong, Bing, Zhou, Hongwei, Zhao, Xiaogang, Chen, Chunhai, Wang, Dezhi, Liu, Changwei, and Qu, Chunyan
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AEROGELS , *SANDWICH construction (Materials) , *THERMAL properties , *LIGHTWEIGHT materials , *THERMAL conductivity , *THERMAL insulation , *FOAM - Abstract
• Unidirectional anisotropic PIAs have been prepared by freeze-drying. • The PIA shows excellent thermal stability and stable mechanical behavior. • The u -PIA-6 exhibits great strength, which is over twice as high as that of the TEEK-HH at 177 °C with a similar density. • The u -PIA shows great thermal insulation properties in anisotropic. Polyimide aerogels (PIAs) are the new type of high-performance lightweight material that combines the excellent thermal and mechanical behavior of polyimides with the highly porous and lightweight properties of aerogels. PIAs can meet the increasing material requirements of high-tech fields such as the aerospace and transportation industries. This study reports a series of all-aromatic anisotropic polyimide aerogels (p-phenylenediamine (PDA) and 3,3′,4,4′-biphenyltetracarboxylic dianhydride (s-BPDA)) with unprecedented behavior. These PIAs were synthesized using a random or unidirectional freeze-drying method followed by thermal imidization of the precursor solution. Their mechanical and thermal conductivity performance were anisotropic (u -PIA-8 strength: 1.86 and 0.14 MPa, thermal conductivity: 62.9 and 50.1 mW·m−1·K−1 along the axial and radial direction, respectively). Furthermore, the PIAs possessed excellent compression behavior in a wide temperature range from 25 °C to 316 °C, with a compressive strength over twice that of the commercial polyimide foam TEEK-HH (u -PIA-6 strength: 0.83 and 0.32 MPa at 177 and 316 °C, TEEK-HH strength: 0.31 MPa at 177 °C). These aerogels also demonstrated good thermal insulation performance after being held at 300 °C for 20 min (u -PIA-8: 76.3 °C at 25 mm). These highly anisotropic aerogels exhibit flexible thermal protection properties that extend the potential use of PIAs to applications such as high-temperature-resistant rocket fairings, sandwich structures, and arc-shaped structures for aerobats or the automobile industry. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
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