Search results for "polyimide"
showing 10 items of 17 documents
Atomic layer deposition of polyimide thin films
2007
The atomic layer deposition (ALD) of different polyimide thin films has been studied. We have demonstrated self-limiting ALD deposition of PMDA–DAH, PMDA–EDA, PMDA–ODA and PMDA–PDA thin films at 160 °C. The maximum deposition rate of 5.8 A cycle−1 was obtained for the PMDA–DAH process. Although the deposition rate was high at 160 °C, a sudden decrease was observed when the temperature was increased. Regardless of the process studied, no film growth was obtained at 200 °C or above. Deposited polyimide films were analysed by FTIR, AFM and TOF-ERDA. According to the FTIR measurements, imide bonds were formed already in as-deposited films indicating polyimide formation without any additional th…
Temperature effects on the performances of the ATHENA X-IFU thermal filters
2016
The X-Ray Integral Field Unit (X-IFU) detector on-board ATHENA is an array of TES micro-calorimeters that will operate at ~50 mK. In the current investigated design, five thermal filters (TF) will be mounted on the cryostat shields to attenuate IR radiative load and avoid energy resolution degradation due to photon shot noise. Each filter consists of a thin polyimide film (~50 nm thick) coated with aluminum (~30 nm thick). Since the TF operate at different temperatures in the range 0.05-300 K, it is relevant to study how temperature affects their mechanical/optical performances (e.g. near edge absorption fine structures of the atomic elements in the filter material). Such results are crucia…
Mechanical and thermal behaviour of networks with “flexible” and “rigid” chains
1996
“Rigid-rod” telechelics were synthesized via repetitive Diels-Alder reaction of biscyclohexadienes and bis(1,2,4-triazoline-3,5-diones). The bistriazolinediones were used in slight excess. The rigidity of the building blocks and the molecular weight were varied. Various amounts of these reactive telechelics are used to crosslink cis-1,4-polybutadiene. The mechanical and the thermal properties of these two-component networks were investigated by stress-strain, differential scanning calorimetry and dynamic-mechanical measurements. The occurrence of microphase separation between the “rigid” and the “flexible” components is discussed to explain the properties of these materials.
Carbon nanotubes embedded in a polyimide foil for proton acceleration with a sub-ns laser
2021
A series of thin films made of aligned carbon nanotubes (CNTs) embedded in a polyimide substrate was designed, fabricated and used for the first time to accelerate protons and C ions by interaction with a sub-nanosecond, high power laser beam (600 J energy and 300 ps pulse width) with peak intensity of about 3 × 1016 W/cm2 on target. Each target was 5 μm thick, and the composite material contained CNTs aligned in different directions in the substrate. The results obtained from the analysis of a Thomson Parabola spectrometer, and of the spots imprinted by ions on a series of PM355 nuclear track detectors, indicate high energies (up to 3 MeV for protons and 9 MeV for C ions) and a marked infl…
Changes in Surface Free Energy and Surface Conductivity of Carbon Nanotube/Polyimide Nanocomposite Films Induced by UV Irradiation.
2021
Changes in surface energy and electrical conductivity of polyimide (PI)-based nanocomposite films filled with carbon nanotubes (CNTs) induced by UV exposure are gaining considerable interest in microelectronic, aeronautical, and aerospace applications. However, the underlying mechanism of PI photochemistry and oxidation reactions induced by UV irradiation upon the surface in the presence of CNTs is still not clear. Here, we probed the interplay between CNTs and PIs under UV exposure in the surface properties of CNT/PI nanocomposite films. Changes in contact angles and surface electrical conductivity at the surface of CNT/PI nanocomposite films after UV exposure were measured. The unpaired e…
Iris-Like Tunable Aperture Employing Liquid-Crystal Elastomers
2014
A liquid-crystal elastomer (LCE) iris inspired by the human eye is demonstrated. With integrated polyimide-based platinum heaters, the LCE material is thermally actuated. The radial contraction direction, similar to a mammalian iris, is imprinted to the LCE by a custom-designed magnetic field. Actuation of the device is reproducible over multiple cycles and controllable at intermediate contraction states.
Fine plastic foil as backing for sputtered nickel targets
2013
Targets of 58Ni and 60Ni with areal density between 71 and 105 μg/cm2 backed with polyimide foil of 35–40 μg/cm2 were prepared by sputtering with Ar ions produced by a home made sputtering device at the Target Laboratory, University of Jyväskylä. The efficiency of the procedure was about 20 %.
Smart artificial muscle actuators: Liquid crystal elastomers with integrated temperature feedback
2015
Abstract We present a smart, thermally stimulated liquid crystal elastomer actuator with an integrated heater and temperature sensor based on deformable polyimide wiring technology. Due to optimal thermal contact to the active material, heating from room temperature to the point of maximum contraction takes only 19.6 s; cooling requires only 5.6 s. The integrated temperature sensor allows closed-loop operation and characterize the thermomechanical properties of the material: open-loop positioning precision was found to be better than 45 μm and no inherent drift or hysteresis were observed. The maximum force generated by the actuator was 133 mN, corresponding to 76 kPa of stress. This ultra-…
Analysis of measurements of stopping powers of formvar, polyimide, polysulfone, and vyns for 3.6 to 10.5 MeV7Li ions
2002
The stopping powers of formvar, polysulfone, polyimide, and vyns for 7Li projectiles have been measured with the transmission technique and thin foil targets. The experimental data have been analyzed in terms of modified Bethe–Bloch theory to extract characteristic values of the mean excitation energy and Barkas effect parameter, as well as to study the effects of including a single effective charge parameter. Results of this investigation are in general supportive of the outcomes of earlier similar studies with protons and α-particles traversing the same target materials in the sense that previously reported trends in projectile-dependent behavior of values of mean excitation energy and Ba…
Optical thermal filters for eXTP: manufacturing and characterization
2020
In order to ensure the effective detection of X-ray astronomical detectors by blocking ultraviolet, visible and infrared light, adding optical thermal filter in front of the load is an effective method. According to the scientific requirements of eXTP, optical thermal filters with aluminized polyimide (PI) film structure had been designed and tested in this paper, the results of mechanical tests including burst pressure, vibration and acoustic tests, also the transparent properties of optics in UV, Vis and IR lights are presented. The mechanical test results show that the filters for LAD and SFA can't pass the acoustic tests, causing the thickness of PI should be increased or a nickel mesh …