CHEMICAL ENGINEERING RESEARCH & DESIGN
·
2022
·
IF 4.119
Mingyang Chen,Rui Yang,Pei Li
Since PMDA-ODA polyimide is insoluble, its soluble precursor PMDA-ODA poly (amic acid) (PAA) is used to prepare hollow fiber membranes (HFMs). Due to the existence of –CO–NH– and –COOH groups, PAA is subject to form hydrogen bonds with water and consequently leads to a very slow phase inversion rate during the non-solvent induced phase inversion process. Therefore, the hollow fiber spinning has to be carried out with a low take-up speed that limits the productivity. In this paper, we increased the take-up speed of PAA hollow fiber to 60 m/min by simply adding LiCl into polymer dope. Moreover, an integrally skinned defect-free PMDA-ODA hollow fiber membrane was obtained at the high take-up speed where the gas permeances were 6.8 ± 0.7, 2.2 ± 0.2, 0.4 ± 0.04 and 0.07 ± 0.01 GPU for H 2 , CO 2 , O 2 and N 2 , respectively, with an ideal selectivity of 3.1 ± 0.3, 31 ± 3.0 and 5.7 ± 0.6 for H 2 /CO 2 , CO 2 /N 2 and O 2 /N 2 , respectively. These results indicated a dense PMDA-ODA layer of 1 μm. To our best knowledge, this is the first time that a defect-free hollow fiber membrane for gas separation is prepared based on PMDA-ODA.
研究领域:
材料科学
·
化学工程
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产品关联
DOI
高影响因子
HIGH PERFORMANCE POLYMERS
·
2022
·
IF 1.73
Rui Yang,Ming Yang Chen,Pei Li
Carbon molecular sieve (CMS) membranes have excellent gas separation property over conventional polymeric membranes and superior anti-swelling property. PMDA-ODA polyimide has high thermal stability and good mechanical property. It has been extensively adopted as the precursor of CMS membrane. However, due to the insoluble nature, PMDA-ODA CMS membranes are limited to configurations like dense symmetric films or composite membranes using porous inorganic or metal substrates. In this work, CMS hollow fiber composite membranes based on an asymmetric PMDA-ODA hollow fiber were successfully prepared for the first time. The neat PMDA-ODA hollow fiber membrane was crosslinked by polyethyleneimine to alleviate pore collapsing during carbonization and then dip-coated by a PMDA-ODA PAA solution to seal the surface defects. The PDMA-ODA CMS composite hollow fiber membranes showed gas permeances of 93.4 GPU, 19.6 GPU, 6.5 GPU, and 4.7 GPU for CO2, O2, N2, and CH4, respectively, with an ideal selectivity of 14.4, 3.0, and 19.8 for CO2/N2, O2/N2, and CO2/CH4 gas pairs, respectively. The attractive gas separation property shows a great potential for industrial application.
研究领域:
材料科学
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化学工程
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DOI
高影响因子
POLYMER SCIENCE SERIES A
·
2023
·Vol. 64
·期 6
·653-661
·
IF 1
Jiang Taijun,Peng Jun,Wang Jin,Yang Jun,Zeng Guangsheng
Abstract The aim was to prepare copolyimide (BPDA/PMDA-PDA) films of low thermal expansion coefficient by incorporating 1,2,4,5-benzenetetracarboxylic anhydride (PMDA) into polymer backbones 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA)/ p -phenylenediamine (PDA). FTIR and WAXD were used to explore the chemical and physical microstructure of the PIs films. DMA, TMA and TGA were used to characterize the mechanical and thermal performance of the PIs film respectively. The results show that the smectic structure of the film was destroyed by introducing rigid PMDA groups. The free volume fraction of polymers reached its maximum value when 40 wt % PMDA was added. The glass transition temperature of the polymers increased from 330 to 430°C and the thermal decomposition temperature declined slightly with the addition of PMDA. The inflection point in thermal expansion coefficient (CTE) of the BPDA-PDA polymers in TMA test reached as high as 470°C. The glass transition temperature of the polymers increased but the service temperature range narrowed with the addition of PMDA. The optimized PMDA concentration to obtain a best CTE was 5% as was revealed by the experimental results. The insights obtained from the experiments indicated that excessive introduction of PMDA into the polymers could increase the glass transition temperature significantly. However, the operating temperature range may be reduced. This research could offer practical and valuable references to the application for co-PI films.
研究领域:
材料科学
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化学工程
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DOI
高影响因子
Petroleum Science
·
2018
·Vol. 15
·期 1
·146-156
·
IF 1.624
Zhang Rui,Xu Xiaoying,Cao Bing,Li Pei
The pyromellitic dianhydride (PMDA) crosslinked poly(vinyl alcohol) (PVA) was coated on top of the PAN ultrafiltration membrane to form a PVA/PAN composite PV membranes for wastewater desalination. The composite membranes have high application value in industrial wastewater treatment. By varying the membrane fabrication parameters including the weight percent (wt%) of the PMDA, the crosslink temperature and duration, membrane with the best desalination performance was obtained. The composite membrane with a 2-μm-thick PVA selective layer containing 20 wt% of PMDA and being crosslinked at 100 °C for 2 h showed the highest NaCl rejection of 99.98% with a water flux of 32.26 L/(m 2 h) at 70 °C using the 35,000 ppm NaCl aqueous solution as feed. FTIR spectroscopy, wide-angle X-ray diffraction, thermogravimetric analysis and scanning electron microscope have been used to characterize the structures and properties of both the crosslinked PVA dense films and PVA/PAN composite membranes. The effects of the concentrations of PMDA, the crosslinking time and temperature to the membrane water contact angle, swelling degree, salt rejection and water flux were systematically studied.
研究领域:
材料科学
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环境工程
✓ 已验证
产品关联
DOI
高影响因子
Journal of Macromolecular Science Part A-Pure and Applied Chemistry
·
2023
·
IF 2.5
Guorong Qiu,Wenshi Ma
The polyimides were prepared by pyromellitic dianhydride (PMDA) or 4,4'-(4,4'-Isopropylidenediphenoxy)diphthalic anhydride (BPADA) as dianhydride monomer and 1,4-bis(4-aminophenoxy)benzene(TPE-Q) or 1,3-bis(4-aminophenoxy)benzene(TPE-R) as diamine monomer. The polyimides were well characterized by FT-IR, thermogravimetric analysis, dynamic thermomechanical analysis, dielectric measurement and tensile test. The flexibility of polyimide molecular chain was judged by the comparison of molecular volumes, molecular length and conformation transition energy through molecular simulations.
研究领域:
材料科学
·
高分子化学
·
介电材料
·
热分析
✓ 已验证
DOI
高影响因子
Desalination and Water Treatment
·
2024
·
IF 1
Rui Zhang,Jingjing Xue,Yuan Li,Bing Cao,Pei Li
To suppress pore collapsing and selective layer thickening of Poly (pyromellitic dianhydride-co-4,4’-oxydianiline) (PMDA-ODA) nanofiltration (NF) membrane during imidization, we proposed a novel two step method. Specifically, a PMDA-ODA polyamic acid (PAA) polymer dope was cast on top of a non-woven polyester fabric and then underwent non-solvent induced phase inversion to form a PMDA-ODA PAA membrane. The membrane was subsequently dried by solvent exchange and chemically imidized to form PMDA-ODA PI membrane. Compared with the thermally imidized PMDA-ODA PI membrane, which had a thick selective layer of 14.5 μm and pure water permeability of 1.5 L/(m 2 ·h·bar), membrane fabricated using the new method had a thinner selective layer of 1.04 μm and 7 times higher pure water permeability of 10.4 L/(m 2 ·h·bar) without losing rejections. Other than that, the NF membrane also showed good separation properties in organic solvent systems. It showed rejections of 87%~95% to Rose Bengal in DMF, THF, and DMSO, with stable permeabilities of 6.1–8.0 L/(m 2 ·h·bar), at a trans-membrane pressure of 20 bar for at least 24 h. Therefore, the PMDAODA PI membranes had great potential for NF in both water and organic solvent systems.
研究领域:
材料科学
·
环境工程
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DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2019
·
IF 7.015
Wenzhong Ma,Taiyu Li,Chao Jiang,Peng Zhang,Li Deng,Rong Xu,Qi Zhang,Jing Zhong,Hideto Matsuyama
Pervaporation (PV) performance of polyimide (PI) membranes has been attempted for the recovery of high concentrations of aprotic solvents, such as N, N-dimethyl formamide (DMF) and N, N-dimethylacetamide (DMAc). In this work, we explored the effect of chain structure on the solvent resistance and pervaporation performance of hydrophilic pyromellitic dianhydride (PMDA) and 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA) based polyimide membranes. According to the Hansen solubility parameters and membrane formation morphologies, we selected five aprotic solvent resistant PI membranes with different chain structures. It was found that the swelling degrees in DMF and DMAc was principally determined by the elasticity modulus of the PI membrane, and was significantly influenced by the polymer chain structure. The flexible linkages (such as –O CH 2 and CH 2 ) suppressed the PI chain packing, which resulted in the d -spacing and fractional free volume ( FFV ) of PMDA based PI membrane was higher than BTDA based PI membrane. BTDA-BZD membrane had the highest elasticity modulus together with the lowest d -spacing value (4.68 Å) due to its symmetric intermolecular interaction and rigid chain structure. PV experiments were conducted with DMF/water and DMAc/water mixtures over a wide range of temperatures (30–60 °C) with 90 wt% solvent concentration. The BTDA based PI (M4) composite membrane showed the highest separating factor around 275 at 30 °C in DMAc solution, which was much higher than in DMF solution (the separating factor is about 70). Furthermore, the chemical and thermal stability test for the PI composite membranes in the presence of the feed solvent under the PV process demonstrated the excellent separation stability in DMAc solution.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2019
·
IF 3.375
Yuan Li,Jingjing Xue,Xu Zhang,Bing Cao,Pei Li
For the first time, we demonstrated that the gelation/nonsolvent induced phase separation (Gel-NIPs) method could be applied to fabricate macrovoid-free flat-sheet nanofiltration membranes based on organo-insoluble polyimide (pyromellitic dianhydride–4,4′-diaminodiphenylmethane; PMDA-MDA). Specifically, the PMDA-MDA polyamic acid (PAA)/N-methyl pyrrolidone (NMP) dope was cast on a polyester-based nonwoven, gelatinized in a fridge, and immersed in water. Gelation greatly inhibited the growth of macrovoids and resulted in an asymmetric membrane with high permeability but low rejection. After adding 4 wt % TiO2 sol into the dope, the gelation process was accelerated, and the PMDA-MDA/TiO2 membrane had a dense skin layer with a macrovoid-free cross-sectional structure. Its permeability and rejection to Rose Bengal (RB, Mw = 1017 Da) were 8.3–9.2 L·m–2·h–1·bar–1 and 89.5–95.7%, respectively, in solvents including DMF, THF, and DMSO. The separation performance was stable at a feed pressure of 25 bar, indicating a great potential for organic solvent nanofiltration (OSN).
研究领域:
材料科学
·
膜技术
·
化学工程
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产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2023
·
IF 8.6
Xiuling Li,Yanan Pang,Yongle Zhang,Bo Ge,Junchang Liu,Yuling Zhang,Limin Zhao,Guina Ren,Zhaozhu Zhang
Solar interface heating evaporators are widely used and have been able to obtain clean water vapor from sewage. However, the soluble contaminants remaining in the original solution were not removed, and the floating organic pollutants affect the steam production rate. In this paper, the superhydrophobic Bi/BiOCl with low surface tension is synthesized and loaded to the felt to construct the floating layer of the photothermal device. The floating layer collaborated with the filter paper hydrophilic layer and the Pyromellitic dianhydride-Tris (4-aminophenyl) amine covalent organic framework (PMDA-TAPA COF) photothermal layer to treat the sewage containing dissolved pollutants, achieving an interfacial evaporation rate of 1.47 kg⋅m −2 ⋅h −1 . Importantly, the floating layer not only has a contact angle of 161°, which can selectively adsorb the organic solvents floating on the water surface, but also can degrade the pollutants dissolved in the water under the light and solving the problems that hinder device applications. The valence band and conduction band potentials of superhydrophobic Bi/BiOCl are at 3.065 eV and −0.435 eV, respectively, which produce h + and O 2 – under light to degrade dissolved pollutants in water. The introduction of novel superhydrophobic Bi/BiOCl photocatalyst in the floating layer provides a reference for solving the problem of pollutant residues.
研究领域:
环境科学
·
材料科学
·
化学工程
·
纳米技术
✓ 已验证
产品关联
DOI
高影响因子
Desalination and Water Treatment
·
2025
·
IF 1
Jingyi Chen,Chunyu Ji,Junsheng Liu,Jie Zhang
A series of new PMDA@CS/PVA composite membranes were fabricated by the crosslinking of pyromellitic dianhydride (PMDA) with chitosan (CS) and poly(vinyl alcohol) (PVA) in the presence of glutaraldehyde (GA) as a crosslinking agent. While, their adsorptions for Cu(II), Co(II), and Ni(II) in a single- and multiple mixed solutions were investigated. It was found that the incorporation of PMDA in the membranes can significantly enhance the adsorption capacity of membranes for these metals. The fitting of kinetic modeling s showed that the sorption manner of Cu(II), Co(II) and Ni(II) on the membranes obeyed the quasi-2nd kinetic modeling, indicating that it was dominated by chemisorption. The kinetic rate constants K 2 of membranes A-E for Cu(II), Co(II), and Ni(II) were in the region of 0.005–0.02, 0.026–0.082, and 0.002–0.053 [g/(h·mg)], respectively. The fitting of sorption isotherm modeling followed the Langmuir isotherm equation and the maximal Langmuir adsorption capacities for Cu(II), Co(II), and Ni(II) could reach 36.466, 32.119, and 30.916 mg/g, respectively. In addition, in the multi-component solutions, these membranes exhibited better selection for Cu(II) in Cu(II), Co(II), and Ni(II) mixed solutions. Moreover, it can be recycled five times when an EDTA was used as a de-sorbent. The exploration based on statistical physics principle confirmed that the adsorption of these membranes for Cu(II) is a mono-ion manner. These findings suggest that PMDA@CS/PVA composite membranes are promising sorbents for the removal of toxic metal ions from waste vehicle power batteries or metal-bearing wastewater.
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产品关联
DOI
高影响因子
RSC Advances
·
2016
·Vol. 6
·期 109
·107533-107541
·
IF 3.289
Xinliang Fang,Shanfeng Wang,Yanxiao Li,Xiaoyun Liu,Xinxin Li,Shaoliang Lin,Zhong-Kai Cui,Qixin Zhuang
Novel Fe3O4/polyimide (PI) composite films with extraordinary dielectric properties were prepared via in situ polymerization of PI in the presence of 4,4′-diaminodiphenyl ether (ODA), pyromellitic dianhydride (PMDA) and compatible amine-functionalized carbon-coated Fe3O4 nanoparticles (Fe3O4@C–NH2). Fe3O4 nanoparticles prepared via solvothermal reaction were coated with crosslinked glucose and then surface-grafted via carbodiimide coupling. The core–shell structure of Fe3O4@C–NH2 was thereafter obtained with amine functionalities on the carbonized-glucose shell. Homogeneous dispersion of Fe3O4@C–NH2 and strong interfacial covalent bonding on the shell surface contributed to high dielectric constants (ε) and extremely low dielectric losses (tan δ) in the composite films. The highest dielectric constant of the composite films was 58.6 at 1 kHz when the Fe3O4@C–NH2 composition was 1.13 vol%, as well as a low dielectric loss of 0.0091 and a high breakdown strength of 126.5 ± 11.3 MV m−1 were observed without considerable sacrifice of the thermal stability and mechanical properties.
研究领域:
材料科学
·
高分子化学
·
纳米技术
·
电气工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2023
·
IF 9.5
Haojie Zeng,Feiyun Sun,Jianjun Zhang,Ying Wang,Songwen Yang,Dingyu Xing
Polyvinyl alcohol (PVA) has been employed and crosslinked as the selective layer of NF membranes with enhanced hydrophilicity. However, the influences of different crosslinking methods and agents on the reaction mechanism and membrane performance still need to be comprehensively studied. In this study, NF membranes were prepared by coating crosslinking (CC-membrane) and gradient crosslinking (GC-membrane) methods. Compared with CC-membrane, the GC-membrane possessed a 65% higher flux with Na 2 SO 4 rejection around 90%, under the optimal preparation conditions with PVA content of 0.10%, curing at 80 °C for 10 min. Crosslinking agents including 1,3,5-benzenetricarboxylic acid (TMA), 4,4′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) and pyromellitic dianhydride (PMDA) with different spatial structure were used to optimize the GC-membrane. As confirmed by SEM, XPS, FTIR and contact angle tests, the 6FDA-GC membrane showed a thinner, smoother and more hydrophilic selective layer, and kept an excellent balance between the water flux (88.6 L/m 2 h) and Na 2 SO 4 rejection (88.7%). This is because the 6FDA with a large molecule and flexible spatial structure could form a more integrated crosslinking structure compared to PMDA. Meanwhile, the 6FDA-GC membrane showed rejections of over 80% towards the endocrine-disrupting compound 17α-Ethinylestradiol and exhibited stable antifouling ability and durability. Overall, this work studied systematically the influences of various crosslinking agents on the GC-membrane, and verified the potential of hydrophilic PVA membranes for nanofiltration.
研究领域:
材料科学
·
化学工程
·
环境科学
·
膜技术
✓ 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）