Papers by Keyword: Polyimide

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Authors: Jia Qi Lin, Hui Lin, Wen Long Yang, Xiao Kang Li, Ying Liu, Zhi Bin Xie, Pa Nan Zhang
Abstract: The surface binding energy between the polyimide(PI) and zinc oxide (ZnO) have been simulated using the molecular dynamics theory.The PI / ZnO model has been established by using Forcite program package of Materials Studio software.The total atoms number about 300 million, the radius of the nano-ZnO cluster model have five groups are respectively 0.5 nm, 1 nm, 1.5 nm, 2 nm, 2.5 nm.The effect of different particle size of nano-ZnO on surface binding energy in PI / ZnO composites was investigated. The relationship between the surface binding energy of PI / ZnO composites and the nano-Zno radius, the maximum of surface binding energy were obtained. The computed results show that the intermolecular bonds between nano-ZnO and PI are mainly van der waals bonds.And the surface atomic number of nano-ZnO increases along with the increasing of nano-ZnO radius, indicating that the increasing of contact surface between the nano-ZnO and PI, which lead to the surface binding energy increases, the total energy lower and the system more stable.
556
Authors: Daniel P. Engelhart, Elena Plis, Russell Cooper, Sunita Humagain, Andrei Koch, Matthew Brunetti, Steven Greenbaum, Ryan Hoffmann
Abstract: Interaction of high energy electrons with spacecraft materials, such as polyimide (PI, Kapton-H®), is known to cause their physical degradation. However, understanding of the chemical nature of this damage and the effect on the electrical and optical properties of PI is still limited. This lack of understanding limits predictive spacecraft models (charging, thermal, etc) as only pristine material properties are used for calculation. This is a major source of error in spacecraft construction and anomaly resolution, since PI properties change after exposure to the space environment. In the presented study, we analyze the chemical, electrical, and optical changes to polyimide after exposure to 90 keV electrons.
48
Authors: Lin Liu, Yun Qing Zhu, Jing Song, Si Chen
Abstract: Multi-walled carbon nanotubes (MWCNTs) are incorporated into Polyimide (PI) film in both pristine and functionalized forms through in-situ polymerization. MWCNTs and NH2-MWCNTs lead to improved mechanical properties such as better tensile strength and elongation at break, as well as increased surface friction coefficient. The NH2-MWCNTs can reduce the total wear weight loss of the composite to a larger extent compared with MWCNTs. 1.0 wt% NH2-MWCNTs/PI has the lowest weight loss of 20.6 % of pure PI. Mechanism of two-stage wear procedure is discussed. We found that PI composite films with lower friction coefficient tend to lose less weight in the first stage, and the ones with better mechanical properties show better wear resistance in the whole wear procedure. Owing to the low surface energy, Natural mica is employed as the substrate for PI film.
88
Authors: Zhao Qing Lu, Qiang Xu, Zhi Jie Wang, Zhen Wu
Abstract: Polyimide fibers and polyamide acid fibers was used as main materials to produce Polyimide fiber paper. A certain amount of PEO and aramid pulp was added and the sheet was treated by immersion and hot pressing in specified process. The experimental results showed that when the dosage of PEO and aramid pulp were 0.06% and 6% respectively, the sheet tended to present more excellent strength properties and electrical performance compared with sheet using single polyimide fibers as the main fiber materials.
603
Authors: Jiu Mei Xiao
Abstract: A simple process to fabricate porous polyimide membranes (PPMs) and effect of warm-up temperature rates on morphologies of the PPMs were reported in this paper. The polymer solution layer consisting of the corresponding polyamic acid (PAA), solvent and the pore forming agents with high boiling temperature or high decomposition temperature was first treated under a lower temperature (about 150°C). The received solid membrane was further imidized by a higher temperature (about 270°C) and the pore forming agents were removed from the membrane at a temperature above their boiling temperature or decomposition temperature at last. Then a PPM was obtained. As the temperature was elevated gradually, the porosity of the received PAA membrane was lower than that of the PPM treated by a faster warm-up temperature rate.
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Authors: Yu Hua Qiao, Huai Min Miao, Yong Biao Xu, Wei Jiang, Yan Hong Zheng, Lian Cai Wang
Abstract: Radiation effects on polyimide (PI) membranes were studied with different irradiation doses by 60Co. The PI membrane were synthesized from 2,2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane (Bis-AP-AF) with 3,3',4,4'-Benzophenone tetracarboxylic dianhydride (BTDA). The single gas permeability of He, H2, CO2, O2, N2 and CH4 were measured and compared in order to determine the effect of the the irradiation doses on the gas separation properties. The results showed that the ideal selectivity of He/CH4, H2/CH4, CO2/CH4 and H2/N2 of the irradiation PI membrane can be significantly improved by irradiation of 60Co source. The optimum irradiation doses were 50 kGy. The highest ideal selectivity of He/CH4, H2/CH4, CO2/CH4 and H2/N2 is 3635.86, 2287.57, 282.00 and 205.29, respectively. In other word, the ideal selectivity of He/CH4, H2/CH4, CO2/CH4 and H2/N2 of the irradiation PI membrane with 50 kGy irradiation doses is 2.27, 2.11, 1.89 and 1.08 times higher than that of the PI membranes without irradiation.
123
Authors: Yan Hong Zheng, Yu Zhai, Jian Mei Guo, Hong Yan Yu, Lian Cai Wang, Xin Miao Zeng
Abstract: Radiation effects on polyimide (PI) films were studied with different irradiation doses by 60Co. The PI film were synthesized from 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (Bis-AP-AF) with 3,3',4,4'-Benzophenone tetracarboxylic dianhydride (BTDA). The tensile strength, tensile modulus and elongation at break of the irradiation PI films were measured and compared in order to determine the effect of the irradiation doses on the tensile properties. The results showed that the tensile strength, tensile modulus and elongation at break of the irradiation PI film can be significantly improved by irradiation of 60Co source. The optimum irradiation doses were 50 kGy. The maximum increment of tensile strength, tensile modulus and elongation at break of the irradiation PI film is 37.8%, 45.0% and 95.2%, respectively.
323
Authors: Sunan Tiptipakorn, Piriyathorn Suwanmala, Kasinee Hemvichian, Yingpit Pornputtanakul
Abstract: In this study, the composites prepared from polyimide (PI) and polyaniline (PANI) were radiated with electron beam (EB) at the radiation doses of 0, 50, 150, 200, and 300 kGy. The electrical conductivity and thermal properties of the radiated composites were determined and compared with those of the composites doped with 6M HCl. The results revealed that the electrical conductivity was enhanced from 3.42 x 10-16 S/cm (untreated polyimide without polyaniline) to 6.97 x 10-5 S/cm when the PI/PANI composite was doped with HCl at 10 phr of PANI; furthermore, the conductivity was increased to 2.16 x 10-4 S/cm for the composite at 10 phr of PANI with radiation dose of 200 kGy. In addition, it was found that the glass transition temperature of the composite was increased with the increase of PANI content for either EB radiation method or protonic acid doping method. It could be noted that the electrical conductivity values of the radiated composites were higher than those of composites doped with HCl at the same PANI content.
861
Authors: Jia Qi Lin, Jun Hui Shi, Jing Leng, Ming Hui Xia, Qing Guo Chi
Abstract: In this paper, ZnO Nano-particles is embedded in polyimide, and physical and chemical properties of polyimide/ZnO composite materials have been studied. It is found that different ZnO content will cause UV absorption edge blue shift, and EL tests show that electricity aging and pre-breakdown have changed. For PI/ZnO(1%) and PI/ZnO(2%) composite materials, Electricity aging is at 1.4Mv/cm and 1.5Mv/cm, Pre-breakdown field is at 1.9Mv/cm and 1.8Mv/cm, respectively. In addition, there are emission peaks at 442.8nm, 514.2nm, 609.4nm in the EL spectrum of the PI/ZnO (1%) films and 538nm, 633.2nm of PI/ZnO(2%) films, which indicates that some defects in this area.
137
Authors: Hirofumi Saito, Hiroki Komatsuzaki, Ryuta Ikoma, Takayuki Komori, Keigo Kuroda, Yohta Kimura, Yudai Fukushi, Hirotaka Maenosono, Syohei Koide, Masahiro Satano, Yasushiro Nishioka
Abstract: Improved fabrication processes of an all-polyimide micro electroosmotic flow pump using hot embossing are described. Microchannels in the micropump were fabricated by hot embossing on a transparent polyimide substrate. A silicon micromachined mold was pressed into the transparent polyimide substrate at a temperature of 300 oC to form microchannel patterns on the substrate. The depth and width of the microchannels were 25 μm and 50 μm, respectively. A UV ozone treatment was performed to improve adhesion between the transparent polyimide substrate and film capping layer. This UV ozone treatment enhanced adhesion and resulted in the reduction of the adhesion temperature as low as 100 oC, and nearly no deformation of the microchannels was observed. As a result, the electroosmotic flow pump exhibited the flow rate of 0.7 μl/min when a voltage of 50 V was given between the electrodes separated 20 mm each other.
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