CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Yuluo Chen,Huicong Liu,Jinpeng Luo,Hang Xu,Xinran Hou,Yujie Yang,Chuanqiang Yin,Xiaomin Li,Lei Ma,Puxuan Yan,Lang Zhou
Polyimide (PI) has been widely used in aerospace, electronic information, novel energy, and other industries due to its excellent high- and low-temperature, radiation, and chemical corrosion resistance . However, the use of electrospun PI separators in lithium-ion batteries (LIBs) is limited due to their poor electrolyte wettability and insufficient mechanical strength . Inorganic materials such as aluminide have typically been used in the coating composition of PI separators. To investigate the effects of different aluminide components, in this work, PI materials were prepared by the complexation–hydrolysis method and used as separators for LIBs. The physicochemical and electrochemical properties of the different nanofiber membranes were studied by adjusting the calcination temperature. The results showed that the sample with the highest tensile strength was 107.6 MPa, which is close to the commercial polyolefin separator. When the calcination temperature increased to 300 °C and then exceeded 400 °C, the aluminide shell initially transformed into thin boehmite and then into γ-Al 2 O 3 phases. The mechanical properties of the nanofiber membranes were enhanced, and the wettability and electrochemical characteristics also improved to some extent. Furthermore, the nanofiber structure was destroyed at 500 °C and could not meet the long-term battery cycles. Therefore, when the calcination temperature was controlled between 300 °C and 400 °C, the aluminide-armored PI nanofiber membranes exhibited better comprehensive performance and were suitable for use as separators in LIBs, which was of great significance for improving the safety and stability of LIBs, especially power batteries.
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高影响因子
LANGMUIR
·
2023
·
IF 3.9
Yihao Nie,Xibin Yi,Xinfu Zhao,Shimo Yu,Minna Zhang,Jian Zhang,Guoliang Dou,Mengdi Wang
Polyimide (PI) aerogel has surfaced in research and development as a result of its heat resistance, flame retardancy, and low dielectric constant. However, it is still a challenge to reduce the thermal conductivity while improving its mechanical strength and retaining hydrophobicity. Herein, the PI/thermoplastic polyurethane (TPU) composite aerogel was synthesized by coupling TPU with PI via a novel method of chemical imidization combined with freeze-drying technology. With this technique, PI aerogel with excellent comprehensive performance is produced. Interestingly, the volume shrinkage of the composite aerogel decreased from 24.14 to 5.47%, which leads to low density (0.095 g/cm3) and elevated porosity (92.4%). In addition, strong mechanical strength (1.29 MPa) and high hydrophobicity (123.6°) were achieved. More importantly, PI/TPU composite aerogel demonstrated a low thermal conductivity of 29.51 mW m–1 K–1 at ambient temperature. Therefore, PI/TPU composite aerogel can be a promising material for hydrophobic and thermal insulation applications.
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PubMed
高影响因子
JOURNAL OF POLYMER RESEARCH
·
2022
·Vol. 29
·期 11
·1-14
·
IF 3.061
Zhang Zhao Xin,Yang Shang Ke,Shen Jun Wei,Yang Jia,Bian Jun,Zhang Ai Ping,Lin Hai Lan,Chen Dai Qiang
In order to systematically investigate the dependence of the properties of nanocomposites on the shape of nanofillers, including spherical and fibrous, and the contents and its special arrangement, polyimide (PI) as matrix, nano-silicon carbide particles (SiC p ) and whisker (SiC w ) as fillers were applied to prepare PI nanocomposite films by in-situ polymerization. FTIR and XRD tests verified the successful polymerization of SiC/PI nanocomposites. FESEM observations showed that both SiC p and SiC w nanofillers were uniformly dispersed in the PI matrix during in-situ polymerization and contributed to the improvements of properties. Compared with pure PI film, addition of SiC nanofillers enhanced obviously the heat resistance and the thermal stabilities of PI nanocomposites, as verified by TGA. Tensile tests indicated that the mechanical properties of PI nanocomposites enhanced with increasing SiC nanofillers. Moreover, SiC w was more prominent than SiC p in the reinforcement of PI nanocomposites. Due to the influences of dielectric properties by the changes of the spatial arrangement and the local distribution of electric field of the nanofillers in PI matrix, the dielectric constant of 3wt.%SiC p /PI and 3wt.%SiC w /PI nanocomposites reached 4.3 and 5.6, respectively. Compared with pure PI film, the dielectric constants of SiC p /PI and SiC w /PI nanocomposites were enhanced by 26% and 64%, respectively. In comparison, PI nanocomposites containing SiC w possessed higher effective permittivity than those containing SiC p under the same nanofillers concentration. This work is expected to show great significance to understand the microscopic mechanism of PI dielectric nanocomposites for high energy-storage applications.
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高影响因子
POLYMER ENGINEERING AND SCIENCE
·
2022
·Vol. 62
·期 12
·4226-4234
·
IF 2.573
Wang Zhang,Hanzhou Jiang,Yong Nie,Xingzhong Fang,Guofei Chen
A series of polyimide/polytetrafluoroethylene (PI/PTFE) hybrid films were synthesized by blending water-soluble polyamide acid salts with water-based PTFE dispersion and thermal imidization to enhance the dielectric proprieties of PI. The relationship between PTFE filler content and the properties of films has been investigated. The results showed that the dielectric properties of PI were effectively improved by PTFE fillers and all films showed excellent heat resistance. When the addition of PTFE filler was 30 wt%, the PI and PTFE in PI/PTFE-30 hybrid film still showed good compatibility and dispersity. The dielectric constant and dielectric loss factor were decreased to 2.42 and 0.0044 at 10 GHz, respectively. Meanwhile, the film PI/PTFE-30 had the lowest water absorption (0.11%) and maximum water contact angle (95.3°).
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JOURNAL OF APPLIED POLYMER SCIENCE
·
2022
·Vol. 139
·期 48
·e53231
·
IF 3.057
Shang Ke Yang,Zhao Xin Zhang,Ai Ping Zhang,Hai Lan Lin,Xun Tao Zhang,Liu Xin Xiao,Jun Bian,Dai Qiang Chen
This work employed polymer active agent polyvinylpyrrolidone (PVP) treated barium titanate (BT) nanoparticles (PVP@BT) as functional nanofillers to fill polyimide (PI) matrix to fabricate PI nanocomposite films. The microstructure, dielectric properties, and heat resistance of PI, PI/BT, and PI/PVP@BT dielectric nanocomposite films were investigated. Fourier transform infrared spectrometer (FTIR) indicated that PVP has been successfully coated on the surface of BT nanoparticles. Due to the enhanced aggregation of monomers on the PVP@BT nanoparticles, higher molecular weight and viscosity of PI/PVP@BT nanocomposite films were achieved. Compared with PI/BT nanocomposite films, the dispersion of PVP@BT nanoparticles in PI/PVP@BT nanocomposite films was better, as verified by field emission scanning electron microscope and high-resolution transmission electron microscopy. Filling a small amount of PVP@BT nanoparticles into the PI matrix improved the dielectric properties of the resultant nanocomposite films. The dielectric constant of the nanocomposite films with 10 wt% filler loading was up to 7.1 at 1000 Hz, which was 2.5 times higher than that of pure PI (2.9). PI nanocomposite film dielectric loss was generally lower than 0.015. Thermogravimetric analysis (TGA) tests verified that both pure PI and PI nanocomposite films showed excellent thermal stability. This work can be expected to provide a new strategy for designing and manufacturing PI dielectric nanocomposite films for energy storage applications.
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ACS Applied Polymer Materials
·
2022
·
IF 4.855
Shuaishuai Liu,Yanyan Wang,Chao Xiao,Miao Jiang,Xin Ding,Hui Zhang,Kang Zheng,Lin Chen,Xingyou Tian,Xian Zhang
Owing to superior comprehensive performance, polyimide film (PI) has been extensively used as flexible substrate to support and fix electronic components. However, the current PI film has inferior thermal conductivity, especially in the vertical direction, causing failure of electronic devices in overheating conditions. Herein, an electrically insulating pea-pod-like filler with high thermal conductivity in both horizontal and vertical directions was prepared by encapsulating interconnected carbon microsphere (CM) with graphene-like carbon nitride (g-C3N4). The resultant thermal conductivity of PI film in horizontal and vertical directions has been improved by 11 (1.98 W m–1 K–1) and 2.4 (0.43 W m–1 K–1) times at 30 wt % CM@g-C3N4 loading, respectively. Furthermore, benefiting from satisfactory light absorption of CM@g-C3N4, the PI/CM@g-C3N4 film displays rapid heating capability under illumination. Meanwhile, the PI/CM@g-C3N4 film keeps intrinsic electrical insulation, thermal and dimensional stabilities. This work provides an effective method to solve the bottleneck of the current PI film in inadequate thermal conductivity.
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高影响因子
REACTIVE & FUNCTIONAL POLYMERS
·
2022
·
IF 4.966
Qian Liu,Zijie Fan,Xibin Yi,Shiwei Chen,Bing Li,Weiyue Luo
The polyimide is a promising semiconductor photocatalyst . However, its photocatalytic activity is poor because of its small specific surface area, low visible light absorption and easy recombination of photoexcited electron and hole. Herein, porous polyimide/carbon quantum dots/ZnS quantum dots material aerogel with excellent photocatalytic performance is prepared via supercritical fluid drying technology. The material aerogel has large surface area and the structure is porous network. The carbon quantum dots increase the visible light absorption of the polyimide aerogel . The ZnS quantum dots change the VB edge, CB edge and band gap of the polyimide aerogel. Both carbon quantum dots and ZnS quantum dots could improve the charge transfer and facilitate the separation of photoexcited electron and hole. The visible-light photocatalytic performance over oxytetracycline of porous polyimide/carbon quantum dots/ZnS quantum dots material aerogel is increased largely compared to pure polyimide aerogel. The photocatalytic degradation mechanism of the polyimide material aerogel is proposed. ·O 2 − and h + play the key role in the photocatalytic degradation. This work supplies an effective method to prepare visible-light photocatalytic materials.
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高影响因子
POLYMERS FOR ADVANCED TECHNOLOGIES
·
2022
·Vol. 33
·期 5
·1685-1694
·
IF 3.348
Huailiang Hui,Yanpeng Li,Yu Feng,Jialong Li,He Zhao,Congcong Zhu,Dong Yue,Jinghua Yin,Xiaoxu Liu
Polymer-based nanodielectrics are widely used in microelectronics, aerospace and electrical insulation fields because of their excellent insulation and mechanical properties, but the strategies and mechanisms to improve their insulation strength need to be further studied. Herein, introducing MOFs (UiO-66) particles into polyimide (PI) matrix obtained the unexpected discovery that MOFs with 3D porous structure did not degrade the insulation strength and mechanical stretching of composite films, conversely, remarkably increased the breakdown strength ( E b ) and mechanical strength at low doping concentration. With only 1 wt% doped of UiO-66, the maximum E b of UiO-66/PI composite film is 458.6 kV/mm, which is about 64% higher than PI (279.8 kV/mm). To study the mechanism of performance improvement, the interface structure was characterized by synchrotron radiation small-angle X-ray scattering, and the interface influence factor is introduced to modify the classical dielectric model. It was found that the hydroxyl groups on UiO-66 can form hydrogen bonds with the PI molecular chain, and this strong interaction at the interface is the main reason for the performance improvement of low-content doped composites. This study provides a strategy for improving the insulation properties of composites at low doping and offers some insights into the application of MOFs in high performance dielectrics.
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高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2022
·
IF 16.744
Jinchao Li,Jun Liu,Wenjie Xu,Jun Long,Wenheng Huang,Yaping Zhang,Liangyin Chu
With an innovatively synthesized X-shaped tetramine monomer 4,4',4'',4'''-(1H,3'H-[5,5'-bibenzo[d]imidazole]) tetraaniline with imidazole groups, a series of novel sulfonated polyimide membranes with covalent self-crosslinking and branching structures (sc-bSPI-x) are designed and prepared for application in vanadium redox flow battery (VRFB). The synergistic effects of protonated imidazole and sulfonic acid are supposed to create proton transport channels and Donnan exclusion, leading to break the trade-off between proton conductance and vanadium ion resistance. Among all the prepared sc-bSPI-x membranes, the sc-bSPI-14 membrane with 14% theoretical cross-linking degree shows the highest ion selectivity (2.78 × 10 5 S min cm −3 ), which is about 6.5 times of commercial Nafion 212 membrane (0.43 × 10 5 S min cm −3 ). The VRFB performances including self-discharge time, coulombic and energy efficiencies at 80–200 mA cm −2 of sc-bSPI-14 membrane are superior to those of Nafion 212 membrane (sc-bSPI-14: self-discharge time 46 h, CE = 97.6–99.2% and EE = 82.9–63.2%; Nafion 212: self-discharge time 11 h, CE = 86.5–94.5% and EE = 78.4–61.4%). Meanwhile, the 1000-time cycling charge–discharge test of sc-bSPI-14 membrane at 140 mA cm −2 is performed, demonstrating its outstanding operational stability. The results indicate that the proposed sc-bSPI-14 membrane is a promising candidate for VRFB application.
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MACROMOLECULAR MATERIALS AND ENGINEERING
·
2022
·Vol. 307
·期 7
·2100941
·
IF 4.402
Long Ni,Yinfu Luo,Baowei Qiu,Liwei Yan,Huawei Zou,Shengtai Zhou,Mei Liang,Pengbo Liu
Lightweight flexible polyimide foams (PIFs) with different rigid-flexible molecular structure networks are prepared by microwave-assisted foaming of polyester ammonium salt (PEAS) precursor powders, followed by post curing process to complete final imidization. The optimum foaming temperatures of PEAS precursors range from 85 to 135 °C, and the melting rate of PEAS is adjusted to meet the volatile releasing rate to fabricate PIFs. Results show that PIFs with nearly fully open cell rate (99.99%), micron pore sizes (400–500 µm), and micro/nano multiscale structures exhibit excellent mechanical flexibility and elasticity. The prepared PIFs demonstrate exceptional thermal stability and heat resistance in both dynamic and static environments. The PIFs possess low thermal conductivity and superior thermal insulation properties that demonstrate potential applications in high-tech fields such as aerospace, marine use, and microelectronics among others.
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APPLIED THERMAL ENGINEERING
·
2022
·
IF 6.465
Zhiheng Zheng,Tao Shi,Huan Liu,Dezhen Wu,Xiaodong Wang
Solar energy is the cleanest and most abundant renewable energy source that can be utilized to displace fossil fuels and provide an effective solution for future energy shortage and climate change. Aiming at enhancing the capture efficiency of solar photothermal energy, we developed a novel type of phase-change composites based on polyimide (PI)/phosphorene (PR) hybrid aerogel and polyethylene glycol (PEG). The composites were prepared by fabricating a series of PI/PR hybrid aerogels with different loadings of PR nanosheets using freeze-drying and thermal imidization techniques, followed by vacuum impregnation of PEG as a phase change material into the aerogel framework. The obtained hybrid aerogels exhibited a lightweight nature with a density of 21.9 mg·cm −3 when 16 wt% PR nanosheets were incorporated, resulting in an extremely high PEG loading of 4067% in the aerogel system. The combination of PI and PR nanosheets leads to a significant enhancement in solar light absorption and photothermal energy conversion for the hybrid aerogel/PEG composites. The loading amount of PEG was also improved remarkably due to an increase in the volume capacity of the hybrid aerogels resulting from the introduction of PR nanosheets. The resultant hybrid aerogel/PEG composites not only exhibit a high latent-heat capacity of over 170 J·g −1 and a high photothermal conversion efficiency of 82.5%, but also show good thermal impact resistance to keep their original shape and form well after heating at 80 °C for 20 min and maintain a high thermal cycle stability after thermally cycled for 500 times. These superior performances make the hybrid aerogel/PEG composites capable of dealing with a wide range of applications in solar photothermal energy capture and storage. This study provides a promising strategy for the design and development of high-performance and lightweight composite PCMs to meet the requirement of applications for efficient utilization of solar energy.
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Gels
·
2023
·Vol. 9
·期 6
·467
·
IF 4.6
Lu Zhao,Junyong Chen,Defang Pan,Yan Hou
The use of energy-saving materials is an effective strategy for decreasing energy consumption and carbon emission. Wood is a type of biomass material with a natural hierarchical structure, which results in its high thermal insulation. It has been widely used in construction. However, developing wood-based materials without flammability and dimensional instability is still a challenge. Herein, we developed a wood/polyimide composite aerogel with a well-preserved hierarchical pore structure and dense hydrogen bonds inside, resulting in its excellent chemical compatibility and strong interfacial interactions between its two components. This novel wood-based composite was fabricated by removing most hemicellulose and lignin from natural wood, followed by the fast impregnation using an ‘in situ gel’ process. The introduction of polyimide into delignified wood substantially improved its mechanical properties, with the compression resistance being improved by over five times. Notably, the thermal conductivity coefficient of the developed composite was approximately half that of natural wood. Furthermore, the composite exhibited excellent fire-retardancy, hydrophobicity, thermal insulation, and mechanical properties. This study provides a novel method for wood modification, which not only aids interfacial compatibility between wood and polyimide but also retains the properties of the two components. The developed composite can effectively reduce energy consumption, making it promising for practical and complex thermal insulation applications.Keywords:wood;polyimide;hydrophobicity;thermal insulation;fire-retardant
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高影响因子
危险品化学品经营许可证（带存储）