JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
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2017
·Vol. 28
·期 20
·15142-15148
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IF 2.019
Chi Qingguo,Gao Zhiyou,Zhang Changhai,Cui Yang,Dong Jiufeng,Wang Xuan,Lei Qingquan
In this paper, sandwich structured polyimide hybrid films were prepared by layered coating, in which middle layer is different volume fraction BT/PI monolayer film and both the bottom and the top layers are pure PI. Compared with monolayer hybrid films, sandwich structured hybrid films exert much lower dielectric loss and conductivity, which owe to pure PI layers as insulation layers effective block off conductive paths of middle layer. Besides, the SEM images show hybrid film has obvious layering and without defects. This sandwich structure can redistribute electric field between three layers to optimize breakdown performance, which correspond to data processed by Weibull breakdown distribution. When the intermediary volume fraction is 3 vol%, the breakdown strength of sandwich structured hybrid films is 344.26 kV/mm, which is 1.26 times enhancement than pure PI film. In addition, based on the improvement of the breakdown strength, the energy storage density of hybrid films is improved significantly. When the electric field is 344.26 kV/mm, its energy storage density reached 1.94 J/cm 3 , which is 1.72 times enhancement of pure PI film.
研究领域:
材料科学
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电气工程
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产品关联
DOI
高影响因子
RSC Advances
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2016
·Vol. 6
·期 65
·60094-60100
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IF 3.289
Jianwei Li,Guangcheng Zhang,Yao Yao,Zhanxin Jing,Lisheng Zhou,Zhonglei Ma
In this research paper, a series of novel polyimide (PI) foams containing benzimidazole units were prepared derived from polyester ammonium salt (PEAS) precursor powders, which were synthesized by co-polymerization of benzophenone-3,3′,4,4′-tetracarboxylic dianhydride (BTDA) with two diamines of 2-(4-aminophenyl)-5-aminobenzimidazole (BIA) and 4,4′-diaminodiphenyl ether (ODA) with various molar ratios. The effects of incorporation of BIA on the morphology, thermal and mechanical properties of co-polyimide (co-PI) foams were explored. The results show that the BIA has a significant influence on foaming degree of PEAS precursor powders. The density of co-polyimide foams increases with increasing the BIA content in the polymer chains. Moreover, the thermal stability of the resultant co-polyimide foams presents a remarkable upward trend with incorporating more BIA units into the polymer chains. As the BIA loading up to 30 mol%, the glass transition temperature of co-polyimide foams increases around 50 °C in comparison with the pristine polyimide foam. Furthermore, the compressive strength of the co-polyimide foams is in the range of 0.30–0.75 MPa, which is superior to their of commercial polyimide foams with the same density. The co-polyimide foams with higher thermal and mechanical properties expand their potential application in many high-tech fields such as aerospace and aviation industries.
研究领域:
材料科学
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高分子化学
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DOI
高影响因子
Polymers
·
2021
·Vol. 13
·期 23
·4174
·
IF 4.329
Yu Sun,Tao Li,Haiyang Dai,Manman Wang,Renzhong Xue,Jing Chen,Dewei Liu
Three fluorinated polyimide (PI-FP, PI-FO and PI-FH) films with low dielectric constants and excellent comprehensive properties were successfully prepared using a polycondensation reaction method by incorporating p-phenylenediamine (PDA), 4-4′-diaminodiphenyl ether (ODA) and 4,4′-(Hexafluoroisopropylidene) bis (p-phenyleneoxy) dianiline (HFPBDA) into 4,4′-(Hexafluoroisopropylidene) diphthalic anhydride (6FDA), respectively. The effects of the diamine monomer structure on optical, dielectric and mechanical properties were investigated. Compared with PDA and ODA, HFPBDA can effectively improve the optical and dielectric properties of PI due to due to its special chain structure. Among the three PI films, PI-FH film presents the best optic transmission (highest transmittance = 90.2%) and highest energy gap (2.69 eV). The dielectric properties of PI-FH film improve the most. The dielectric constant and loss at 104Hz are reduced to 2.05 and 0.0034 at 104Hz, respectively, and remain stable up to 250 °C. The mechanical properties decrease in turn for PI-FP, PI-FO and PI-FH films due to the increase in free volume fraction. Nevertheless, PI-FH film still exhibits good mechanical properties with a tensile strength of 88.4 Mpa, a tensile modulus of 2.11 GPa and an elongation at break of 4.1%. The correlation between the dielectric and mechanical properties of PI films and their free volume characteristics is well explained with the help of positron annihilation spectroscopy.Keywords:polyimide;low dielectric constants;positron annihilation;free volume fraction
研究领域:
材料科学
·
物理学
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产品关联
DOI
PubMed
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2022
·
IF 4.326
Yinfu Luo,Long Ni,Xueqin Zhang,Xinyue Jiang,Huawei Zou,Shengtai Zhou,Mei Liang,Pengbo Liu
Rigid polyimide foams (PIFs) with excellent compressive and thermal properties were fabricated by thermal foaming of polyester ammonium salts (PEAS) precursors which were terminated by 5-norbornene-2,3-dicarboxylic anhydride (NA). The melt viscosities of PEAS precursors were found essential to obtaining PIFs with high closed cell ratios and improved interactions between foam cells, which were indispensable to improving mechanical properties. The room temperature compressive strength and compressive modulus of PIF (density: 146.3 kg m–3) with four repeating units reached 1.55 and 23.3 MPa, which were 7 and 9 times higher than that of PIF-∞ (230.9 kg m–3), respectively. Furthermore, the room temperature compressive strength of PIFs with foam densities of 358.3 kg m–3 reached 9.79 MPa. The PIFs demonstrated outstanding thermal properties with initial thermal degradation and glass transition temperatures higher than 450 and 290 °C, respectively. The thermal conductivities of PIFs fell in a range of 0.071–0.073 W m–1 K–1, which showed promising applications in the fields of aerospace, aeronautics, and marine use as high temperature-resistant structural materials.
研究领域:
材料科学
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化学工程
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产品关联
DOI
高影响因子
IONICS
·
2022
·Vol. 29
·期 2
·685-693
·
IF 2.961
Li Jinyun,Li Wenwen,Deng Guoxiong,Qin Ying,Wang Hongyan,Wang Yunjia,Xue Song
Cuprous oxide (Cu 2 O) is a promising photocathode for photo-electrochemical hydrogen production. One of the main issues limiting the application of Cu 2 O is photo-corrosion in aqueous electrolyte during the PEC process. Herein, to improve the stability of Cu 2 O, for the first time, a soluble polymer polyimide (PI) was introduced as a protective layer using a facile spin-coating method. It was found that dense PI films effectively isolated Cu 2 O from the aqueous electrolyte and inhibited self-reduction and oxidation reactions of Cu 2 O as evidenced by XRD spectra. Compared with bare Cu 2 O, the photocurrent density and stability of modified Cu 2 O samples were increased with increasing the spin-coating amount of PI solutions. It was found that sample Cu 2 O/PI-200 showed the highest current density value of 1.8 mA/cm 2 at 0 V RHE after 1200 s without attenuation, which is 40 times higher than the bare Cu 2 O (0.04 mA/cm 2 at 0 V RHE ). Further enhancing the PI amount, such as sample Cu 2 O/PI-300, will lead to a very stable but lower current density (1.48 mA/cm 2 ) during the whole test duration. EIS measurements indicated that thicker PI films lead to larger charge transfer resistance and higher capacitance in the space charge layer. Therefore, there is an optimum amount of PI (Cu 2 O/PI-200) to balance the above two opposite effects and achieve the best PEC performance. This work provides a facile strategy to improve the PEC activity and stability of Cu 2 O, which may be extended to other systems with photo-corrosion problems, such as BiVO 4 or ZnO.
研究领域:
材料科学
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能源研究
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DOI
高影响因子
COMPOSITES COMMUNICATIONS
·
2023
·
IF 8
Kaiqing Yao,Shaohua Jiang,Shanshan Li,Chunmei Zhang,Haoqing Hou
Facile techniques that are time- and cost-saving nowadays are required for preparing PI aerogels with low density, structural stability, high mechanical performance, and thermal stability in wide practical applications. In this work, a strategy of solvothermal imidization followed by vacuum drying, using electrospun short polyimide (PI) fiber as supporting skeleton, was reported to prepare high-performance PI aerogels without the implementations of special drying instruments. The mechanism of “self-gluing” of the fiber-constructed skeleton of PI during preparation process was applied to enhance the strength of the precursor gels and achieve structural stability. PI aerogels with hierarchically cellular structure possessed bimodal interconnected pores, tunable densities (From 39.1 mg cm −3 to 55.8 mg cm −3 ), and high porosity (>96%) are reported. The aerogels showed low energy-loss coefficients for 10 3 cyclic compressive tests and initial degradation temperature high than 400 and 500 °C in air and nitrogen atmosphere, respectively.
研究领域:
材料科学
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化学工程
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产品关联
DOI
高影响因子
Science China-Materials
·
2023
·Vol. 67
·期 1
·272-278
·
IF 8.1
Zhang Yajun,Han Meikang,Hu Rongxiang,Zhang Peigen,Pan Long,Sun ZhengMing
Constructing three-dimensional (3D) porous structures is an effective method to improve microwave absorbing performance due to the multiple reflections. However, in traditional 3D porous structures, multiple reflections only occur within the pores. Promoting multiple reflections beyond the pores should further improve the absorbing performance. Herein, a 3D porous composite foam with sandwiched cell walls was developed to boost multiple reflections in both the submillimeter-scale pores and the submicron-scale cell walls, achieving multiscale microwave absorption. Polydopamine (PDA)-modified polyimide foam (PIF) was used as the 3D porous skeleton. The cell walls of the PDA@PIF were sandwiched by Ti 3 C 2 T x MXene. The resulting Ti 3 C 2 T x @PDA@PIF can absorb over 90% of the incident microwave over the whole X band, which is contributed by multiscale multiple reflections, conduction loss, and interfacial polarization. Meanwhile, the composite foam exhibits excellent flexibility and a low density of ∼30 mg cm −3 . This work offers a realistic approach for lightweight, flexible, and broadband microwave absorbers, enriching the structures for effective electromagnetic protection.
研究领域:
材料科学
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电磁学
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产品关联
DOI
高影响因子
POLYMER COMPOSITES
·
2023
·Vol. 44
·期 7
·4134-4141
·
IF 5.2
Hui Gao,Jinrong Li,Fangong Kong,Zhaojiang Wang,Feng Xu
Shape memory polyimides (SMPI) with adjustable shape recovery temperatures have been paid much attention in both fundamental research and practical applications. However, the intrinsically electrical insulation of SMPIs limits their applications. In this article, the electrically conductive shape memory polyimide-polyaniline (SMPI-PANI) composite with interpenetrating networks was synthesized by in situ polycondensation. Compared with pure SMPI, the electrical resistivity of SMPI-PANI composites reduced by about 12 orders of magnitude when the PANI content was 15 wt%. The addition of PANI had less influence on the glass transition temperature and storage modulus in glassy state. But the storage modulus of SMPI-PANI composites in rubbery state was over 40 times higher than that of pure SMPI, indicating that SMPI-PANI composites have higher stiffness during shape recovery. The SMPI-PANI composites demonstrate excellent shape memory performance with shape fixation ratio higher than 97% and shape recovery ratio higher than 93%. The SMPI-PANI composites also have good thermal stability with the effective decomposition temperatures higher than 150°C. The SMPI-PANI composite in our work is a potential material for deployable aerospace structure.
研究领域:
材料科学
·
高分子化学
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产品关联
DOI
高影响因子
COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING
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2023
·
IF 8.7
Xinzuo Huang,Rongxiang Hu,Fenghua Zhang,Yanju Liu,Jinsong Leng
An innovative process for producing flexible transparent graphene electrodes has been proposed. The electrochemically polished copper-foil was used as the metal substrate to prepare high-quality monolayer graphene. Monolayer graphene was transferred from copper-foil to transparent shape memory polyimide (TSMPI) intactly by novel flow-casting transfer technology, and the smart, ultra-clean and smooth flexible graphene electrode (pG@TSMPI) was fabricated. The light transmittance of pG@TSMPI at 550 nm is 86%, the average sheet resistance is 310 Ω/sq, and the surface roughness (Ra) is 18 nm. Smart white OLED was manufactured using pG@TSMPI as transparent anode, and its luminescence performance was comparable to that of ITO-based device. Depending on the shape memory effect of TSMPI substrate, the smart OLED has the superiorities of variable stiffness and reconfigurable shape, which can transform from 2D structure into complex 3D structure.
研究领域:
材料科学
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光电技术
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DOI
高影响因子
HIGH PERFORMANCE POLYMERS
·
2017
·
IF 1.179
Jianwei Li,Guangcheng Zhang,Zhanxin Jing,Jiantong Li,Lisheng Zhou,Hongming Zhang
In this study, a series of porous polyimide films containing benzimidazole units were prepared through a phase separation process. The dibutyl phthalate was selected as porogen. The copolyimides were prepared by the reaction of 3,3′,4,4′-benzophenonetetracarboxylic dianhydride with two diamines of 2-(4-aminophenyl)-5-aminobenzimidazole (BIA) and 4,4′-diaminodiphenyl ether with various molar ratios. The resultant porous polyimide films exhibit optimum cell-size distributions. The effects of BIA on morphology, mechanical, and thermal properties of the porous films were explored. It was found that as the BIA content reached up to 30 mol%, the porous copolyimide film demonstrates remarkable thermal stability and admirable mechanical properties with the glass transition temperature of 294°C, 5% weight loss temperature in argon flow up to 545°C, and a tensile strength of 48 MPa. The incorporation of BIA into the polyimide chains brought the highly rigid structures and strong intermolecular interactions, resulting in the enhancement in the thermal stability and the mechanical properties.
研究领域:
材料科学
·
化学工程
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DOI
高影响因子
HIGH PERFORMANCE POLYMERS
·
2017
·
IF 1.179
Guangliang Song,Lina Wang,Dandan Liu,Jianan Yao,Yiming Cao
Polyimides (PIs) with single phenyl pendant substitution were prepared based on three diamines containing phenyl pendant group, namely, 2,5-bis(4-aminophenoxy) biphenyl, 2-phenyl-4,4′-diaminodiphenyl ether, and 2,5-diaminobiphenyl (p-PDA), with the dianhydride component of 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and 3,3′,4,4′-biphenyltetracarboxylic dianhydride, respectively. The physical properties of the membranes were examined, including thermal properties, fractional free volume (FFV), solubility, and morphological structures, and were compared with the analogues without phenyl pendant. Gas transport properties of the membranes were investigated and discussed from the viewpoint of structure–property relationship. For 6FDA-derived PI membranes, gas permeability increased as the degree of PI backbone rigidity leveled up. Gas transport properties were not improved by the incorporation of phenyl pendant group for 6FDA type containing ether linkage and marginally improved as compared between PI (6FDA/p-PDA) and PI (6FDA/p-phenylenediamine (PDA)). To increase the phenyl substitution density of 6FDA/PDA-type backbone, a novel diamine bearing two phenyl pendant groups, that is, 2,6-diphenyl-1,4-diaminobenzene (p, p′-PDA) was synthesized, and PI derived from 6FDA and p, p′-PDA was prepared. The gas permeability coefficients of PI (6FDA/p, p′-PDA) were remarkably larger than those of PI (6FDA/p-PDA) and PI (6FDA/PDA).
研究领域:
材料科学
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化学工程
✓ 已验证
DOI
高影响因子
HIGH PERFORMANCE POLYMERS
·
2020
·
IF 1.568
Pengfei Jiang,Hongge Jia,Jingyu Xu,Hailiang Zhou,Mingyu Zhang,Shuangping Xu,Yu Zang,Xunhai Zhang,Yuyan Zhang
In this study, we firstly used 1-carboxyethyl-3-methylimidazolium ionic liquid as a capping agent to terminate a binary linear polyimide containing different groups such as ether bonds, carbonyl groups, and fluorine, and prepared six kinds of polyimides capped with ionic liquids (IL-PI). The mechanical properties of the polyimide membranes capped with ionic liquids were higher than those of the uncapped polyimide membranes. The elastic modulus of polyimide membrane from 1,3-bis (4-aminophenoxy) benzene (BPDA) and 3,3′4,4′-benzophenone tetracarboxydianhydride (BTDA) by using ionic liquid as the end capping agent (IL-BPDA-BTDA) was 2012 MPa, which is about 70 times higher than that without the end capping agent. In a TG test, all polyimides capped by ionic liquids showed good thermal properties. The residual amount of the polyimides was more than 40% at 1000 °C, which was higher than the other uncapped polyimides. In conclusion, polyimide membranes with high temperature resistance and high mechanical strength were prepared through an ionic liquid termination method.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）