JOURNAL OF APPLIED POLYMER SCIENCE
·
2020
·Vol. 138
·期 9
·49911
·
IF 2.52
Jian-Ni Liu,Da-Yong Wu,Wei-Hua Liang,Jian-Hua Cao
Achieving excellent thermal stability, good mechanical strength, and low-density in one product, is a big challenge in the design and synthesis of polyimide (PI) foams. We selected a rigid diamine monomer, 2-(4-aminophenyl)-5-aminobenzoxazole (DAPBO) to partially replace 4,4′-oxydianiline (ODA) in BTDA-ODA system, and studied the effect on properties of foamed PI products. With various molar ratio between DABPO and ODA (0:5, 1:4, 2:3, 3:2, 4:1, 5:0), the diamine(s) polymerized with 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA) and produced six PI precursors (PAE-0 ~ PAE-5). After foaming and thermal imidization, corresponding PI foams (PI-0 ~ PI-5) prepared. Among them, PI-3 has a glass transition temperature of 386°C, which is 95°C higher than PI-0, and its compressive strength reaches 1.32 MPa. Moreover, PI-3 has a uniform cell structure with an average pore size of ~200 μm. The analysis results show that PI-3 is in a transition state from amorphous to partial crystalline, maintaining a balance between flexibility and rigidity. The addition of DABPO not only increases the rigidity of polymer molecular segments, but also introduces N and O atoms that can form intermolecular hydrogen bonds between molecules, which increases the packing density and arrangement regularity of polymer molecules.
✓ 已验证
产品关联
DOI
高影响因子
CHINESE JOURNAL OF CHEMICAL ENGINEERING
·
2020
·
IF 2.627
Tadele Daniel Mekuria,Lei Wang,Chunhong Zhang,Ming Yang,Qingtao Lv,Diaa Eldin Fouad
Polyimide (PI) composite films were synthesized incorporating amino modified silicon nitride (Si 3 N 4 ) nanoparticles into PI matrix via in situ polymerization technique. The mechanical and thermal performances as well as the hydrophobic properties of the as prepared composite films were investigated with respect to the dosage of the filler in the PI matrix. According to Thermogravimetric (TGA) analysis, meaningful improvements were achieved in T 5 (5% weight loss temperature) and T 10 (10% weight loss temperature) up to 54.1 °C and 52.4 °C, respectively when amino functionalized nano-Si 3 N 4 particles were introduced into the PI matrix. The differential scanning calorimetry (DSC) results revealed that the glass transition temperature ( T g ) of the composites was considerably enhanced up to 49.7 °C when amino functionalized Si 3 N 4 nanoparticles were incorporated in the PI matrix. Compared to the neat PI, the PI/Si 3 N 4 nanocomposites exhibited very high improvement in the tensile strength as well as Young’s modulus up to 105.4% and 138.3%, respectively. Compared to the neat PI, the composites demonstrated highly decreased water absorption behavior which showed about 68.1% enhancement as the content of the nanoparticles was increased to 10 wt%. The SEM (Scanning electron microscope) images confirmed that the enhanced thermal, mechanical and water proof properties are essentially attributed to the improved compatibility of the filler with the matrix and hence, enhanced distribution inside the matrix because of the amino groups on the surface of Si 3 N 4 nanoparticles obtained from surface functionalization.
✓ 已验证
产品关联
DOI
高影响因子
COMPOSITES COMMUNICATIONS
·
2020
·
IF 4.915
Menglin Li,Lei Sheng,Rong Xu,Yang Yang,Yaozong Bai,Shangjun Song,Gaojun Liu,Tao Wang,Xianli Huang,Jianping He
Polyimide (PI) nanofiber membrane prepared by electrospinning technique exhibits poor mechanical strength for the slippage of fibers, which limits it applied into lithium ion battery (LIB). In this study, we are devoted to promoting the macro mechanical strength of PI nanofiber membrane by inhibiting the slippage among the fibers. Lithium polyacrylate (PAALi) is a kind of excellent binder, and it contributes to increasing the adhesion effect between the fibers. As a result, the PI nanofiber membrane treated by PAALi solution shows the mechanical strength of 16.1 MPa, higher than 5.0 MPa of pristine PI membrane. The introduction of this binder makes the originally loose and disordered PI nanofibers cross-link with each other and prevents from the slip between the fibers. Surprisingly, the PAALi binder has no effect on the thermal stability and electrochemical performance of PI nanofiber separator. Furthermore, these LiCoO 2 /Li cells using the modified PI nanofiber separators exhibit better cycling stability and superior rate performance compared with the cells containing pristine PI separators. It demonstrates that the use of PAALi binder is a promising method to improve the mechanical strength of nanofiber membrane, which gets it applied in the high-power LIB.
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF POLYMER RESEARCH
·
2020
·Vol. 27
·期 6
·1-5
·
IF 2.426
Wang Zhanwen,Li Shizhuo,Wang Jianhua,Han Enlin,Tian Guofeng,Wu Dezhen
Polyimide (PI)/ bisphenol A dicyanate esters (BADCy) composite laminates with varying resin contents were prepared by filament winding and autoclave molding process. The laminates exhibited ultralow dielectric constant ( ε of 3.15–3.25) and dielectric loss (tan δ of 0.004–0.006) as well as excellent mechanical properties. When the resin content was 35.6%, the composite achieved outstanding comprehensive properties with tensile strength and modulus equal to 1485.1 MPa and 80.9 GPa, respectively, and the inter-laminar shear strength (ILSS) up to 66.2 MPa. The failure mode of laminates followed an explosive gage middle (XGM) mechanism, which suggested a favorable interface between fiber and resin. According to the mixed law equation, PI fiber at a frequency of 10.2 GHz exhibited dielectric constant of 3.41 ± 0.03 and dielectric loss of about 0.002–0.004. The successful preparation of PI fiber reinforced BADCy composite with low dielectric constant provides new ideas for material design and selection of lightweight high-strength structural-functional integrated composites.
✓ 已验证
产品关联
DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2021
·
IF 4.539
Yizhi Zhao,Zhigang Shen,Xiaojing Zhang
Graphene and graphene/nanoparticles were explored to enhance the atomic oxygen (AO) corrosion resistance of polyimide (PI) composites. Graphene flakes (EGs) were produced by electrochemical method using alternating current (AC). A series of EGs/PI composite films were prepared by in-situ polymerization. After exposure to AO, although all EGs/PI composite films were resistant to AO, we found a much greater enhancement, i.e. adding 1.5 wt% EGs can reduce the mass loss of the composite by 42%. On this basis, EGs/SiO 2 and EGs/Al 2 O 3 co-doping fillers were firstly used to further enhance the AO corrosion resistance of PI. The sample co-doped 1.5 wt% EGs with 3 wt% SiO 2 could achieve a 71% decrease in the composite’ mass loss. Bonding effect and barrier effect of graphene fillers are responsible for the enhanced protective performance. At the same time, the “synergistic effect” between EGs and nanoparticles also plays a role in the enhancement. These preliminary but interesting results pave a novel way for the study of AO corrosion resistance.
✓ 已验证
产品关联
DOI
高影响因子
Advanced Fiber Materials
·
2021
·Vol. 4
·期 1
·108-118
·
IF 0
Li Jianwei,Zhang Xuanning,Lu Yuyan,Linghu Keliang,Wang Chen,Ma Zhonglei,He Xinhai
The separator with excellent mechanical and thermal properties are highly required for lithium ion batteries (LIBs). Therefore, it is crucial to develop novel nanofibrous membranes with enhanced mechanical strength and thermal stability. In this work, the fluorinated polyimide (FPI) was synthesized and blended with polyvinylidene fluoride (PVDF) to fabricate composite nanofibrous membranes (CNMs) via electrospinning method. Benefiting from the introduction of aromatic FPI, the prepared PVDF/FPI nanofibrous membranes were endowed with enhanced mechanical strength and thermal stability. When the FPI content increased from 0 to 30 wt%, the tensile strength of composite nanofibrous membranes enhanced from 1.57 to 2.30 MPa. Moreover, there are almost no dimensional shrinkage for the CNM-30 containing 30 wt% FPI after heat treatment at 160 °C for 1 h. Furthermore, the prepared CNMs show improved electrochemical performances in comparison with neat PVDF and commercial Celgard membranes. The electrolyte uptake and ionic conductivity of the CNMs could reach to 522.4% and 1.14 ms·cm −1 , respectively. The prepared CNMs could provide an innovative and promising approach for the development and design of high-performance separators.
✓ 已验证
产品关联
DOI
Energy Technology
·
2019
·Vol. 8
·期 1
·1901013
·
IF 3.163
Xufei Liu,Peng Mei,Sheng Lei,Xiaofang Zhang,Qian Liu,Yingkui Yang
3D N-doped carbon nanobelt (NCB) networks are fabricated by one-pot hydrothermal polycondensation of co-monomer salts of dianhydride and diamine followed by carbonization of the resulting nanobelt-like polyimides. As control samples, solvothermally polymerized petal-like polyimides and conventionally polymerized spindle-like polyimides are also produced, which further yields N-doped carbon petals and N-doped carbon spindles after identical carbonization, respectively. Interestingly, all N-doped carbons copy the morphologies of their polyimide precursors well. Specially, the 800°C-treated NCB exhibits a robust 3D architecture composed of intertwined nanobelt networks with high N-doping levels and electroactivity-enriched N configurations. Remarkably, the symmetric supercapacitor assembled by such NCB electrodes delivers large specific capacitance (193 F g −1 at 1 A g −1 ), high rate capability (176 F g −1 at 20 A g −1 ), and long cycling stability (nearly 100% retention over 10,000 cycles at 20 A g −1 ). The energy density is as high as 27 Wh Kg −1 at the power density of 500 W Kg −1 , and retains 24 Wh Kg −1 at the power density up to 20,000 W Kg −1 . This work opens up an affordable and scalable approach to the rational fabrication of heteroatom-contained carbon materials for high-performance supercapacitors with well-balanced power and energy output.
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF POLYMER ENGINEERING
·
2019
·Vol. 39
·期 10
·917-925
·
IF 1.072
Danbo Mao,Gang Lv,Guohan Gao,Bin Fan
Optical polyimide (PI) films were prepared by spin-coating from nearly non-volatile dimethylacetamide (DMAc) solutions. The uniformity of film thickness met the requirements of diffraction imaging quality. The results show that the final rotating speed ω , dynamic viscosity η , and initial polymer solid concentration c are the main factors affecting the film thickness T , and an empirical relationship which describes the film thickness as a function of the measured parameters was established to be T ∝ c 3.473 , η 0.586 , ω − 0.811 . Moreover, the viscosity dependence on concentration is system specific. Unlike traditional photoresist, the thickness uniformity of the PI film is determined by both spinning and precure process, which is intensively discussed in the present work. Uniform, 22-μm thick, PI films with transmitted wavefronts peak to valley (PV) ≤ 1/5 λ and root mean square (RMS) ≤ 1/50 λ were prepared under the optimum process: spin speed 900 rpm, initial fluid viscosity 10,500 cp, final spin time 120 s, precure temperature 70°C, spin process repeated 3 times. The results will find use in the production of optical quality membrane for ultra-lightweight optics or other applications.
✓ 已验证
产品关联
DOI
高影响因子
Polymers
·
2019
·Vol. 11
·期 12
·2068
·
IF 3.164
Huiwen Qu,Zhiliang Wang,Dingyong Cang
Polymer, especially polyimide (PI), is the best suitable substrate material for the design of flexible electronics. The compact silver can be reduced on the surface of PI films by surface modification and in situ self-metallization technique. The formed silver layers have good electrical and mechanical flexibility. A flexible bandpass filter on a PI flexible substrate by surface modification and in situ self-metallization technique at room temperature are presented in this work. Measured results show that the proposed flexible bandpass filter could achieve a fractional bandwidth of 80.8% with an insertion loss (IL) of less than 0.6 dB. The performance of the designed filter is almost constant under different bending, folding, and rolling conditions. The formed silver layers also present good adhesion with PI substrates. This technology provides an alternative approach for manufacturing flexible filters without high-temperature thermal annealing, costly equipment, and vacuum conditions.Keywords:flexible electronics;polyimide substrate;bandpass filter;surface modification;in situ self-metallization
✓ 已验证
产品关联
DOI
PubMed
高影响因子
MACROMOLECULAR MATERIALS AND ENGINEERING
·
2019
·Vol. 304
·期 4
·1800709
·
IF 3.038
Hui Tong,Jing Fu,Aftab Ahmad,Tao Fan,Yudong Hou,Ju Xu
Polymer dielectrics, with advanced dielectric properties and heat resistance, are critical for high-temperature capacitors in various applications. However, the high performance of heat resistance and dielectric properties are quite difficult to achieve all together due to their mutual implication. Here, by intensively investigating the correlation between molecular structure and properties, polyimide dielectrics with i) enhanced dielectric constant by introducing sulfonyl group, ii) low dissipation factor by introducing flexible linkage, and iii) high T g (glass transition temperature) by retaining an aromatic structure, are obtained. The sulfonyl-containing polyimides with different flexible linkages exhibit simultaneously a high dielectric constant (4.50–5.98), low dissipation factor (0.00298–0.00426), and outstanding breakdown strength (most above 500 MV m −1 ), as well as superior heat resistance ( T g : 244–304 °C). Specifically, the polyimide (SPI-1) with sulfonyl group in diamine moiety and para-para linkage shows stable dielectric properties up to 150 °C, and the discharged energy density and charge–discharge efficiency can be as high as 7.04 J cm −3 and 91.3% at 500 MV m −1 , respectively.
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
·
2019
·Vol. 136
·期 24
·47638
·
IF 2.188
Zhongche Liu,Wenjing Ma,Mengjie Zhang,Qilu Zhang,Ranhua Xiong,Chaobo Huang
The oil–water separation technologies of removing oil pollutants from water in an efficient and economical way is a challenge. The current methods used for oil–water separation suffer many shortcomings, including a low separation efficiency, complex separation equipment, high operation costs, and secondary pollution. In this study, we fabricated a highly flexible, high-intensity, quite stable superhydrophobic and superoleophilic polyimide (PI) nanofibrous membranes, which are much more efficient and cost efficient for oil–water separation by modifying the membranes with a polydopamine (PDA) solution and polytetrafluoroethylene (PTFE) dispersion. The fabricated membrane (PDA–PTFE–PI) possesses both the high tensile stress of PI and the superhydrophobic and superlipophilic properties of the PDA–PTFE coating. The modified membrane could separate various oil–water mixtures efficiently at a high flux (6000 L·m −2 ·h −1 ) and an extremely high efficiency (>99%). Furthermore, even when the membrane was under an extremely hostile environment (with an ultrahigh temperature, strong acidity, or strong basicity), it still remained quickly stable with a good separation efficiency and recyclability after 10 cycles. We anticipate that our study will provide a new technology for the highly efficient mass production of oil–water mixture management. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136 , 47638.
✓ 已验证
产品关联
DOI
高影响因子
Smart Materials and Structures
·
2019
·Vol. 28
·期 5
·055031
·
IF 3.543
Xinzuo Huang,Fenghua Zhang,Yanju Liu,Jinsong Leng
Colorless shape memory polyimide (CSMPI) has potential applications in broad fields, especially in advanced optoelectronics due to the excellent optical transparency, shape memory effect and high temperature resistance. In this work, high flexible dianhydrides and fluorine-containing diamines were used to synthesize CSMPI, which simultaneously combined great shape memory performance with high optical transparency. The effects of monomer ratios and imidization temperatures on the molecular structure and properties were investigated. Moreover, the CSMPI film possesses a higher glass transition temperature (Tg) of 234 °C, compared with the reported transparent shape memory polymers. Most importantly, the transmittance of CSMPI film is 87%–90% at 450–800 nm, meeting the requirements of heat resistance and transmittance of the substrate. Both shape recovery and shape fixity are over 97%. Flexible and colorless CSMPI films severed as substrates provide more potential in optoelectronic devices such as OLED and OPV, etc.
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）