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This study presents a comprehensive experimental project in polymer chemistry, centered on polyimide aerogels. The project encompasses the synthesis, structural characterization, mechanical property evaluation, and molecular dynamics simulations of aerogels. Emphasis is placed on the application of interdisciplinary knowledge and innovative experimental design. The educational framework adheres to an "Inspiration-Design-Experiment-Insight" research exploration model. This model begins by igniting students' interest in research, progresses through the design of experimental plans, proceeds to the execution of experimental procedures, and culminates in the analysis of results and the derivation of insights. The objective is to incrementally deepen students' understanding of chemistry and polymer science, foster innovation and research interest, and develop scientific thinking and literacy. [ABSTRACT FROM AUTHOR]

3, 3 5, 4, 4 5 -Biphenyltetracarboxylic dianhydride is a precursor of high・per£ormance material polyimide. This article adopts the method of Grignard reagent coupling to study the synthesis of 3, 3 ', 4, 4 J -biphenyl tetracarb oxy lie dianhydride ・ Firstly, 4 ・brom o・o-xylene reacted w 让h magnesium metal to prepare Grignard reagent・ Secondly, under the action of ferric trifluoromethanesulfonate, the Grignard reagent self-coupled to produce 3, 3 ', 4, 4' -tetramethyl biphenyl, which was oxidized and then dehydrated to ob・ tain 3, 3 '-biphenyl tetracarboxylic dianhydride・ The effects of key factors of the experiments were examined, the optimal reaction conditions of coupling were determined・ The reaction mechanism has been analyzed ・ The results showed that the coupling reaction temperature was 60 °C and the reaction time was 8 h, the yield of 3, 3 ', 4, 4 '・tetramethylbiphenyl reached 83% ・ The yield of 3, 3 ', 4, 4' -biphenyltetracarboxylic dianhydride was 78% ・ Mechanism analysis shows that Grignard reagent undergoes self coupling reaction with iron catalyst and 1, 2-dichloroethane to prepare 3, 3', 4, 4' -tetramethylbiphenyl. [ABSTRACT FROM AUTHOR]

The thermal aging process of polyimide is simulated by reactive molecular dynamics method to simulate the property changes of plasma-modified polyimide materials after thermal cracking. By studying the generation of gas during aging, it was found that as the temperature increases, the interaction forces between molecular chains weaken, resulting in a decrease in the denseness of the material, a decrease in the modulus of elasticity, and a decrease in the ability of the material to resist external stress. At the same time, the relative dielectric constant of the polyimide material increases due to the increase of temperature, and the insulation property of the material decreases and the breakdown strength is also weakened. [ABSTRACT FROM AUTHOR]

A novel fluorinated diamine monomer (FPMDA ) was synthesized from p-fluorobenzaldehyde and 2, 6-dimethylaniline, and then reacted with pyromellitic anhydride to obtain a fluorinated polyimide (FPI). The structures of the synthesized FPMDA diamine monomer and polyimide were characterized by FTIR, nuclear magnetic hydrogen spectroscopy, and mass spectrometry (MS) ;the thermal properties of the polyimide film were characterized using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The results showed that FPI has excellent solubility in solvents such as DMF, NMP, and THF. FPI also shows good thermal stability, under nitrogen environment, with thermal decomposition temperature Td5% of 550 °C, Td10% of 580 °C, and char yield of 58.7% at 1 000 °C, its glass transition temperature is greater than 400 °C . [ABSTRACT FROM AUTHOR]

Copyright of Journal of Tiangong University is the property of Journal of Tianjin Polytechnic University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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In this paper, stannous oxide (SnO) was synthesized by hydrothermal method, and then the obtained SnO was introduced into polyimide matrix by in-situ polymerization method to prepare SnO/PT composite films. The contents of SnO have significant influence on the dielectric constant, dielectric loss, tensile strength and breakdown strength of the film. When the contents of SnO was 1 Owt%, the dielectric constant of the SnO/PT composite film was as high as 456, the dielectric loss was only 0.034, the tensile strength was 65 MPa, and the breakdown strength was 146.9 MV/m, respectively. The introduction of SnO into PT could greatly improve the dielectric properties of the composite PT films, so that it has a good application prospect in energy storage, aerospace, insulation and other fields. [ABSTRACT FROM AUTHOR]

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Shape memory polymers (SMPs) are a class of smart materials that have the ability of transform shape in response to external stimuli, such as heat, light, electricity and magnetic. To design suitable macromolecules and crosslinking mode of polyimide to obtain shape memory polymer with high transition temperature, high strength for application of aerospace, high temperature and other harsh environment is very important. Herein, using well-dispersed graphene oxide (GO) as the reinforced phase, polyhexahydrotriazine crosslinked polyimide/graphene shape memory composite (PI-PHT) was prepared by solvent volatilization and high temperature cyclization. The structure of the materials was characterized by nuclear magnetism and infrared spectrum demonstrating the successful preparation of composites. The mechanical properties tested by universal testing machine showed that after introduction of graphene, the strength, toughness, thermo-mechanical properties and shape memory properties of the composite were significantly improved. When the mass fraction of GO was 5%, the tensile strength and toughness of PI-PHT reached 105.7 MPa and 12.4 MJ/m3 , respectively (1.3 times and 2 times higher than that of PI-PHT without adding GO, respectively) duo to the strong interaction between the well-dispersed grapheme and polyimide. The shape memory properties and shape recovery force were detected by dynamic thermo-mechanical analyzer. The results showed that the shape fixation rate, recovery rate and recovery stress of PI-PHT-5% reached 97.2%, 92.6% and 9.46 MPa, respectively [ABSTRACT FROM AUTHOR]

Copyright of China Synthetic Fiber Industry is the property of Sinopec Baling Petrochemical Company and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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Polyimide(PI) composite films were prepared by the method using 4,4'-diaminodiphenyl ether(ODA) as the diamine monomer, phthalic anhydride (PMDA) as the anhydride monomer, 3-aminopropyltriethoxysilane (KH550) as the coupling agent, and isopropanol aluminum [Al(OPri)3] as the aluminum source・ PI was used as the matrix, and A1O(OH) served as the reinforcement phase・ The structure and properties of the composite films were characterized by SEM, FTIR, XRD, TG, DSC, water contact angle measurement, paint film marker, and pencil scratch tester. The results show that the thermal stability of the composite films first increases and then decreases with the increase of the content of aluminum soL When the content of aluminum sol is 10%, the A1O(OH)/PI composite films exhibits the best high-temperature resistance, with the 5% weight loss temperature reaching 567 °C and the glass transition temperature of 381.4 °C.. [ABSTRACT FROM AUTHOR]

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In order to ensure the normal operation and safety at work of electronic equipment, the research on thermal management of electronic components has continued increasing in recent years. Graphite film produced with polyimide (PI) as the substrate is an important thermal conductivity material, and its thermal conductivity can be improved through doping modification. Compared with solid thermal conductive filler, ionic liquid has better compatibility with polyimide matrix, and has been commonly used in gas separation membrane, colorless polyimide (CP1) and other applications. This article used 4, 4'-diaminobenzoylanilide (DABA) and 3, 3', 4, 4'-biphenyltetracarboxylic dianhydride (BPDA) as monomers, and modified PI films by using l-ethyl-3-methylimi-dazolium bis[(trifluoromethyl)sulfonyl]imide(lL) that had the characteristic of multiple hydrogen bond sites. Then, high thermal conductivity graphite film was prepared by graphitization. The research results show that when the 1L content is 5.0 wt%, the grain size of the graphite film is 78.417 nm, the degree of graphitization reaches 88%, and the thermal conductivity reaches 770 W/mK, which is 1.53 times that of the pure PI cornerstone ink film. [ABSTRACT FROM AUTHOR]

Polyimide (PI) separator with high porosity was prepared by non-solvent induced phase transformation method, and the PI separator was modified by using hexagonal boron nitride (h-BN) and nano-alumina (Al2O3) as blend coating. By adjusting the blending mass ratio of h-BN and Al2O3, the PI composite separator with different coating effects was obtained. The chemical structure and micromorphology of the separator were characterized, and the comprehensive electrochemical performance of the separator and the inhibition effect on lithium dendrites were explored. The results show that when the mass ratio of h-BN and Al2O3 is 8:2, the PI composite separator shows the best comprehensive electrochemical performance. The ionic conductivity and lithium ions transfer number reached 0.871 mS/cm and 0.54, respectively. The discharge specific capacity was 118.9 mA·h/g at 5 C, and the capacity retention rate was 80.2% after 300 cycles at 1 C current density. The composite separator can effectively inhibit the growth of lithium dendrites and ensure the stability of the battery for a long-time cycle. [ABSTRACT FROM AUTHOR]

Various aromatic diamines and dianhydride monomers were selected to synthesize binary or multistructured polyamide acid solutions by solution polymerization, and the corresponding structured polyimide films were prepared by solution casting and thermal amination. The effects of different monomers, compositions, and other factors on the properties of polyimide were explored by testing and characterizing the structures and properties of polyamide acid (PAA) and polyimide (PI). This experiment is based on industrial practice, which is consistent with the process of industrial research and development. Encouraging students to deeply understand the relationship between the structure and performance of polymer materials can stimulate their innovative thinking and cultivate their ability to analyze and solve practical engineering problems. [ABSTRACT FROM AUTHOR]

Firstly, imide diacid monomer (ODPA-GABA) was synthesized by the imidization reaction between 4,4’-oxydiphthalic anhydride (ODPA) and aminobutyric acid (GABA) . Then, a series of polyimides (PIs) with amide group were prepared by Yamazaki phosphorylation of ODPA-GABA with three different diamine monomers. The structure and properties of PIs were deeply researched. It is found that the introduction of alkyl chain effectively improved the solubility of PIs, making them soluble not only in strong polar high boiling point solvents such as m-cresol and N-methylpyrrolidone (NMP), but also in tetrahydrofuran and chloroform. The synthesized PIs possessed good thermal stability, their initial decomposition temperatures θi under nitrogen atmosphere were above 400 ℃, and the values of glass transition temperature (θg) were in the range from 186 ℃ to 208 ℃．In addition,all PIs could be easily processed into flexible films by the solution casting or blade coating due to the improved solubility.All the resulting PI films showed good transparency of over 85%at 500nm.Meanwhile,due to the strong hydrogen bond interaction between the amide structure,PI films exhibited excellent mechanical and thermal mechanical properties,which is expected to be used as the substrate materials for organic optoelectronic devices. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Petrochemical Universities / Shiyou Huagong Gaodeng Xuexiao Xuebao is the property of Journal Editorial Department Of Liaoning Shihua University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Polymer Materials Science & Engineering is the property of Sichuan University, Polymer Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Silver modified aminated carbon nanotubes(MWCNTs-ODA/Ag) were prepared by functionalizing carbon nanotubes with silver nitrate(AgNO3) and 4, 4'-diaminodiphenyl ether (ODA). After in-situ polymerization, coating and thermal amination, MWCNTs-ODA/Ag/PI composite films were obtained by using ODA and pyromellitic dianhydride (PMDA) as polyimide (PI) monomers and MWCNTs-ODA/Ag as nano fillers. The effects of different nano filler contents on properties of the composite films were analyzed. The results show that when the addition amount of MWCNTs-ODA/Ag is 3% (mass fraction, the same below), the tensile strength of Ag/PI-3% film is 123.0 MPa, which is 17.9% higher than Ag/PI-0% film. The thermal conductivity reaches 0.55 W·m-1·K-1, which is 5 times that of Ag/PI-0% film. The thermal conductivity of the composite film is greatly improved with excellent mechanical properties and heat resistance.

In order to meet the application requirements of polymer composite coating under high temperature conditions and promote the practical application of polymer organic composite coating in the field of high temperature protection, polyimide (PI) was selected as the resin matrix, and the heat resistance was modified and enhanced by adding nano-Si3N4. Moreover, the effects of silane coupling agent KH550 and different content of Si3N4 on the surface state and heat resistance of the coating were studied. Results showed that the glass transition temperature (Tg) of the composite coating with 10% (mass fraction) Si3N4 increased to 495 ℃, which was higher than that of pure PI coating (483 ℃). After the addition of KH550, on one hand, KH550 introduced amino functional groups on the Si3N4 surface to cross-link it with the PI molecular chain; on the other hand, KH550 directly interacted with PI molecules to enhance the viscosity of the coating, so that the dispersion of Si3N4 and the binding force of the coating and the substrate were significantly improved. Besides, the PI composite coatings with different contents of Si3N4 were prepared for comparison, and it could be found that the PI composite coating with 10% Si3N4 exhibited the optimal heat resistance and surface quality.

The water-soluble thermoplastic polyimide sizing agent was synthesized from bisphe- nol A-type diether diether dianhydride (BPADA), m-phenylenediamine and 4, 4′-(1, 3-phenylenedioxy) dianiline (TPE-R). The surface of domestic high-strength and high-modulus carbon fiber (HMCF) was sized and prepared into composite material. The effects of molar ratios of different monomers on the characteristics of the sizing agent and the surface structure properties of the fibers after sizing treatment were studied, and the effects of thermoplastic sizing agents on the interfacial properties of domestic high-strength and high-modulus carbon fiber reinforced thermoplastic polyetherketone (PEKK) resin matrix composites were further analyzed. The results show that when the monomer molar ratio of BPADA to TPE-R is 1∶1, the synthesized thermoplastic sizing agent not only has a uniform molecular weight distribution, but also has excellent thermal stability, e.g. its thermal weight loss is only 5% with the temperature up to 554 ℃. After sizing, the surface O/C ratio is increased from 0.08 to 0.18 (increased by 125%). Besides, the fiber strength is slightly increased and the modulus is almost unchanged. More importantly, the interfacial performance of the composites is significantly improved after sizing treatment, and the interlaminar shear strength of the HMCF/PEKK composites can be improved from 38.5 MPa to a maximum of 59.4 MPa with an increase of up to 54.3%.

The performance change and mechanism of polyimide composites with carbon fiber sizing and desizing states during thermal aging at 330 ℃ were compared and analyzed from the aspects of thermal oxidation mass loss, surface morphology and micro morphology, mechanical properties and glass transition temperature. The results show that carbon fiber desizing can reduce the mass loss rate of thermal oxidation of polyimide composites. The interface layer of the composites with sizing carbon fiber contains epoxy sizing agent, which has low temperature resistance. Therefore, the interface is easy to be damaged in the process of thermal aging, resulting in more cracks and rapid separation of edge fibers. Although the composites with sizing carbon fiber has high interlaminar shear strength before aging, it decreases rapidly in the early stage of thermal aging. On the contrary, the interlaminar shear strength of the composites with desizing carbon fiber is higher after aging for 200 h. The bending strength of the two composites before aging is basically the same, but the bending strength of the composites with sizing carbon fiber decreases rapidly in the early stage of aging; however, desizing has little effect on bending modulus. The glass transition temperature of the composites with desizing carbon fiber increases by about 15 ℃. After thermal aging, the glass transition temperature of the composites with sizing carbon fiber increases slightly, while the composites with desizing carbon fiber remain unchanged. Therefore, the high temperature desizing treatment of carbon fiber is conducive to improving the stability of polyimide composites for long-term use at high temperature.

Tn this study, Fe3O4 magnetic material was prepared by co--precipitation method, and polyimid-based polyporous carbon/nano-magnetic iron particles (PTC, PTC/Fe-l, I〉IC/Fe-2, I〉IC/Fe-3 composite absorbent with different amounts of magnetic particles were prepared by vacuum freeze-drying and high-temperature pyrolysis. The excellent heat resistance of polyimide ensures the integrity of pore structure during high temperature pyrolysis. The complete porous structure can improve the impedance matching condition. The addition of an appropriate amount of nano-magnetic iron particles can improve the dielectric loss and increase the magnetic loss, which makes the electromagnetic wave decay rapidly in the absorber. When I/Fe-2 thickness is 4,57 mm, the minimum reflection loss (RLmm) is -24.1 3 dB. When I/Fe-2 thickness is 4,89 mm, the effective absorption bandwidth (EABW, greater than 9()%EMW absorption, RL less than -10 dB) is 2.54 GHz. Tn addition, when PTC/Fe-3 thickness is 4. 91 mm, RL ]rijH is -54. 43 dB, and when I〉IC/Fe-3 thickness is 5.18 mm, EABW is 2.65 GHz. The polyimid-based multi-pore carbon/nano magnetic iron particle absorbent designed in this work has excellent EMW absorption performance and can be used as a candidate for absorbing agent. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Donghua University (Natural Science Edition) is the property of Journal of Donghua University (Natural Science) Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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Polyimide（PI） material has become a hot precursor for the preparation of graphite cooling film in recent years because of its six-membered ring molecular structure and high carbon content. As a transition metal element, nickel is often used as the substrate for graphene catalytic growth. Doping nickel in the polyimide substrate can effectively improve its carbonization and graphitization degree and improve its thermal conductivity. However, pure nickel metal particles will deposit in the precursor of PI, polyamide acid（PAA）, which makes it difficult to disperse uniformly. In this work, the PI composite film was prepared by adding a metal complex soluble in organic solvent, nickel acetylacetone（Ni（acac）2）, into the PI matrix and graphitized at 2 700 ℃ to obtain a graphite film. The nickel obtained from the decomposition of Ni（acac）2 at high temperature can promote the carbonization of polyimide, and its solubility in organic solvent also significantly improves the dispersion of nickel in the PI matrix. Finally, the polyimide carbon film with a flat surface was prepared, and its thermal conductivity can reach 782 W/（m·K）, which is 30 times higher than that of the carbon film prepared by pure PI. The purpose of this paper is to analyze the carbonization process of polyimide catalyzed by metal complex Ni（acac）2 and the final carbon film structure, and explore the possibility of finally preparing high thermal conductivity graphite film.  [ABSTRACT FROM AUTHOR]

Copyright of Polymer Materials Science & Engineering is the property of Sichuan University, Polymer Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Surface modification of poly(benzoxazole-imide) (PI) film was carried out by means of oxygen plasma treatment. A flexible copper clad laminate (FCCL) was fabricated using Ni-Cr ion implantation and electro-Cu plating process. Controlling the constant pressure, the effects of such treatment conditions as power and time were systematically investigated on the surface roughness, chemical composition and interface adhesion with Cu. It is found that the optical parameters for production of FCCL with excellent adhesion and solder resistance are 50 W/5 min and 100 W/10 min, respectively. Suitable roughness, reactive radical with high content pendent oxygen group, and metal-oxazole complex help to endow exceptional adhesive property to the interface of PI/Cu. And the peel strength of FCCL prepared from PI film with such modified surface rises by 60%.

According to the flanged structure of composite casing, a typical sample with laminated structure manufactured by RTM process was designed using T800 grade carbon fiber fabrics reinforced polyimide composite. The strength property under the uniaxial tension condition was simulated by finite element method, and the calculated fracture load was 21.7 kN. The maximum strain was appeared at the corner of flanged structure, indicated that the corner area of flanged structure was weak relatively. Ultrasonic C-scan and optical microscope methods were applied to analyze the internal quality of the corner area. The results show that the overall internal quality of the sample corner area is good without obvious delamination defects. However, some micro-pores enriched at near surface and the fill region are still visible. The measured average tensile fracture load is 19.81 kN, and that is very close to the calculated value. After cyclic loading with 25% of the fracture load for 24000 times, the residual tensile fracture load is still 19.94 kN, this result means fatigue test has no effect to the mechanical property of the samples. Little interlayer defects and cracks happened in several samples at the corner area, but no visual damage. It shows that the sample can still bear the load after the delamination defects appear.

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In order to improve wear comfortability and durability of protective clothing for medical use, the washable fabric of protective clothing for medical use was developed. Its protective performance was studied. Four kinds of fabrics for medical protective clothing were prepared by point-type offline composite processing technology with polyimide nanofiber membrane via electrospinning as core barrier layer and woven fabrics as inner and outer layers. The fabric appearance, protective properties, comfortability and mechanical properties before and after washing were tested and analyzed. Results showed that the protective fabrics prepared with polyester/cotton blended woven fabric as outer layer had excellent protective performance, wear conformability and mechanical properties after 20 times washes. It could meet the wash resistant of protective clothing for medical use. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Materials Engineering / Cailiao Gongcheng is the property of Journal of Materials Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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Copyright of Journal of Donghua University (Natural Science Edition) is the property of Journal of Donghua University (Natural Science) Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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