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YOSHIO IMAI
1994 Volume 7 Issue 2 Pages
251-256
Published: 1994
Released on J-STAGE: August 04, 2006
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This paper reviews recent progress in synthetic methods for aromatic polyimides in terms of conventional two-step, one-step, and three-step process where tetracarboxylic acid derivatives or diamine derivatives are used as starting materials with some emphasis on author's works.
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YUKISHIGE KITANO
1994 Volume 7 Issue 2 Pages
257-260
Published: 1994
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A review is given on the application of molecular simulation technique to calculate the crystal structure of polyimides showing some selected examples, which include a comparison between molecular sumulation technique and X-ray diffraction analysis of the rigid-rod aromatic heterocyclic polyimide, a structural characterization of an ordered aromatic polyimide, ‘Kapton’, and an X-ray structural analysis of a thermoplastic polyimide.
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SEI-ICHI MUKAI
1994 Volume 7 Issue 2 Pages
261-272
Published: 1994
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The process for the formation of high-modulus structure was re-examined through the cast films fabrication study for poly bis 2, 2′-disubstituted biphenylene pyromellite imides (PBPPI-XX: substituents). As the result, it has been clarified that the imide-cyclization behaiviors during intermediate curing zone below 250°C play influential parts and the introduction of volumetrically moderate substituents like methyl group and so on are helpful for the improvement of tensile properties. The reason can be consistently explained from TMA diagrams in this intermediate curing zone rather than from WARD profiles.
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TAKASHI YAMASHITA, HAN-SUNG YU, HIROSHI YOSHIMOTO, KAZUYUKI HORIE
1994 Volume 7 Issue 2 Pages
273-274
Published: 1994
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MASATOSHI HASEGAWA, TAKAFUMI MATANO, YOICHI SHINDO, TOKUKO SUGIMURA
1994 Volume 7 Issue 2 Pages
275-280
Published: 1994
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The degree of in-plane molecular orientation of the unstretched polyamic acid(PAA) films and the corresponding polyimide (PI) film cured thermally have been quantitatively estimated by measuring the dichroic ratio of a rigid-rod dye (perylenebisimide) dispersed molecularly in their films at an incidence angle. Thermal imidization of PAA(BPDA/PDA) cast on a substrate enhanced markedly the degree of in-plane orientation of the PI chains, meaning that spontaneous in-plane molecular orientation occurred without stretching of the film. However, no spontaneous in-plane orientation was observed for BPDA/ODA system as well as PMDA/ODA system. Thus, it was found that the spontaneous orientation behavior depends strongly on the PI chain rigidity or linearity in contrast to that the degree of in-plane orientation for various PAAs is essentially independent of the chemical structure. PI(BPDA/PDA) cured in free-standing showed the degree of the in-plane orientation much smaller than the PI film imidized on a substrate.
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Tomoyuki Yuba, Shiyoshi Yokoyama, Masa-aki Kakimoto, Yoshio Imai
1994 Volume 7 Issue 2 Pages
281-284
Published: 1994
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YOICHI SHINDO, MASATOSHI HASEGAWA, YOICHI SONOBE, TOKUKO SUGIMURA
1994 Volume 7 Issue 2 Pages
285-292
Published: 1994
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The intermolecular crosslinks and the changes in polymer coil dimension during the competitive intra-and intermolecular photocrosslinking reactions were studied for polyimides of benzophenoneteracarboxylic dianhydride with oligomers having various degrees of bis(aminopropyl) polydimethylsiloxane (BAPSX, n=8, 15, 61) in tetrahydrofuran under u.v.irradiation at 30°C. The magnitude of M
w, <s
2>
1/2, and A
2 was evaluated by a light-scattering measurement. The deviation of the intermolecular crosslinks from linearity during the reaction becomes more pronounced as the initial polymer concentration decreases or the number of BAPSX oligomers in a polyimides increases. The value of Φ
inter/[C]
θ for a polyimide with a BAPSX oligomer (n=8) was determined to be 6.7×10
2 dm
3 mol
-1 in the early stage of crosslinks formation. The extent of the contraction of polymer coils due to intramolecular crosslinking increases as the number of BAPSX oligomers in a polyimide decreases.
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Tsuguo YAMAOKA, Shoichi YOKOYAMA, Toshihiko OMOTE, Kazuhiko NAITOH
1994 Volume 7 Issue 2 Pages
293-298
Published: 1994
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Hiroyuki Hiraoka, Stefan Lätsch, Mariana Sendova
1994 Volume 7 Issue 2 Pages
299-308
Published: 1994
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Pulsed laser applications to surface modifications have been practised for many years with carbon dioxide laser in materials processings such as drilling, welding, cutting and surface treatment by its thermal effect. However, with advent of pulsed UV-laser which includes excimer lasers and Nd:YAG laser in 3rd and 4th harmonic modes, pulsed laser application to surface modification becomes more precise, and fine-tuned, as has been well demonstrated by clean wall-profile of ablated holes made by an excimer laser in comparison with those by carbon dioxide IR-laser. Our interest here ranges from nano-structure fabrication using pulsed polarized laser beams to metal deposition on fluorocarbons and to crystalline diamond deposition from plumes generated by an excimer laser photoablation of polymers in presence of reactive species. These studies will be reviewed with those of other groups.
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V.N. VASILETS, T.I. YURANOVA, A.N. PONOMAREV
1994 Volume 7 Issue 2 Pages
309-314
Published: 1994
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Changes in wettability and surface structure of Siloxane polymers under vacuum ultraviolet (VUV) irradiation (wavelength 147nm) and storage in water were investigated by contact angle measurements and ATR FTIR spectroscopy. The increase of wettability observed after VUV irradiation is associated with the formation of CO and OH polar groups in the polymer surface layer. Storage in water and air media of VUV treated samples leads to the increase of contact angle which could be related to dissolution of small highly polar fragments in water or to decomposition of unstable products of photooxidation. Correlation of contact angle changes with the water content in the polymer surface layer observed during storage in water for untreated samples leads to the conclusion that in this case water sorbtion is the major path to wettability changes.
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MASAYUKI KUZUYA, JUNJI NIWA, YUKINORI YAMAUCHI, SHIN-ICHI KONDO
1994 Volume 7 Issue 2 Pages
315-318
Published: 1994
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MASAAKI KATOH, TAKEO OHTE, AKIRA KOJIMA, SUGIO OHTANI
1994 Volume 7 Issue 2 Pages
319-326
Published: 1994
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This investigation was conducted on the surface modification of various carbon by radio-frequency (13.56MHz) glow discharge plasmas with the objective of investigating the effects of fluoric gas plasmas on carbon surfaces and the mechanism of the elapsed variations of the various carbon surface after the plasma treatment. The surface of various carbon was treated by fluoric gas plasmas(SF
6, CF
4, C
2F
6, CHF
3). The contact angles of water to the each carbon surface after the plasma treatment were measured and their elapse changes were investigated. The contact angle of three materiales increased by fluoric gas plasmas. CHF
3 plasma was the most effecient of the plasmas we used. AG plate showed the largest angle in this case. Next we investigated the elapsed change of contact angle of each carbon material after CHF
3 plasma treatment. The contact angle change with time was almost constant. The reasons for the elapsed changes are as follows. Three types in relation to the attachment of F atom are considered. In two types F part from the surface of materials. As a result, F quantity in surface decreases, and the contact angle reduces.
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TAKEO OHTE, MASAAKI KATOH, YORI IZUMI, SUGIO OHTANI, AKIRA KOJIMA
1994 Volume 7 Issue 2 Pages
327-336
Published: 1994
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This investigation was conducted on the accurate control of the surface characteristics of the glassy carbon (GC) by radio- frequency (13.56MHz) glow discharge plasmas. We developed two methods of controlling surface characteristics. These were the mixed gas (SF
6+O
2) plasma treatment method and two-step plasma (SF
6 plasma, O
2 plasma) treatment method. The contact angle of water to the GC surface was controlled by these methods. The mixed gas plasma method was the best, because the control of the contact angle is easy and wide, and the contact angle change with time after the plasma treatment could be minimized by this method.
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G.K. Vinogradov, S. Gorwadkar, K. Senda, S. Morita
1994 Volume 7 Issue 2 Pages
337-340
Published: 1994
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M. KOGOMA, K. KOIWA, S. OKAZAKI
1994 Volume 7 Issue 2 Pages
341-344
Published: 1994
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SiNx thin films have been deposited by using glow discharge with He/SiCl
4/N
2/H
2 and He/SiCl
4/NH
3 gas systems under atmospheric pressure. With the He/SiCl
4/N
2/H
2 system, the SiNx films were obtained at 40°C which have as good quality as the that of those obtained in low pressure glow discharge. In the case of He/SiCl
4/NH
3 gas system, we got films of the same quality with lower temperature about 25°C in that of the He/SiCl
4/N
2/H
2 system. Because NH
3 (N-H bonds) has the lower bond strength than N
2(N-N bond) and H
2(H-H bond), NH
3 is easily dissociated to make NH and H radicals in plasma and easily abstracts the Cl atoms 2 from SiCl
4. That is the reason why attained the lower temperature deposition could be in the containing NH
3 gas system.
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TAKAO HIRAIDE, HIDEO YAMADA
1994 Volume 7 Issue 2 Pages
345-352
Published: 1994
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Organosilicon compounds were deposited in an RF cathode coupled plasma using Tetramethoxy silane. The films were deposited on silicon and glass substrates in negative self-bias voltages over the range of -80V to -580V. The deposited films were highly crosslinked and optically highly transparent between optical wavelengths from 420nm to 1000nm when oxygen was infused with the monomer.
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KEISUKE ISHII, YOSHIMICHI OHKI, TOSHIKI NAKANO
1994 Volume 7 Issue 2 Pages
353-360
Published: 1994
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In order to make clear the breakdown mechanism in plasma polymer films of ethylene and those of ethylene and trifluoromethane, high-field conduction, dielectric breakdown and photoconduction characteristics were studied. The attention was given to the determination of carrier species which causes avalanche. It was found that all these characteristics depend on the anode metal. When the anode is aluminum, the barrier height for tunneling injection obtained from the Fowler-Nordheim relation is higher than the gold anode. The aluminum anode also has a higher dielectric strength and a longer time lag to breakdown than the gold anode.
From these results, together with the effect of the shape of illuminated electrode on photocurrent, it is considered holes are injected through tunneling from the anode by high electric stress applied and that avalanche is caused by these holes.
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TETSUMI SUMIYOSHI, YUTAKA NINOMIYA, HIROSHI OGASAWARA, MINORU OBARA
1994 Volume 7 Issue 2 Pages
361-368
Published: 1994
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Ablation of organic polymers (PES: polyether sulphone, PEEK: polyether ether ketone, and ETFE: ethylene tetrafluoroethylene) by an oscillation line of selected TEA CO
2 lasers is successfully demonstrated. The ablative etch rate slopes were varied with different irradiation conditions such as incident laser intensity and ambient gas. As an application of the ablation processing, spatial periodic structure is fabricated on the surface of the PEEK film by two-beam interference irradiation of the TEA CO
2 laser. It is found that the fluorocopolymer modified by copolymerization has a significant absorption in the oscillating wavelength region of the TEA CO
2 laser and it can be ablated efficiently.
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HIROYUKI NIINO, AKIRA YABE
1994 Volume 7 Issue 2 Pages
369-372
Published: 1994
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SHINGO INOUE, TAKEO FUJII, YOSHIAKI UENO, FUMIHITKO KANNARI
1994 Volume 7 Issue 2 Pages
373-380
Published: 1994
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Crystalline thin films of polytetrafluoroethylene were deposited on Si (100) wafers by F
2 laser (157nm) ablation. X-ray photoemission spectra indicated that the composition of deposited films was similar to the source material. The surface morphology of films deposited at room temperature contained numerous fibrous structures in size of 100-400nm, but they were smoothed out at elevated wafer temperature of -370K. The refractive index was -1.35 at 633nm. Ionized fragments in the ablation plume were measured by a Faraday cup assembly, but their effect on the deposited films was not observed at the present ionization ratio.
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Masayuki OKOSHI, Masataka MURAHARA
1994 Volume 7 Issue 2 Pages
381-388
Published: 1994
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Polyethylene surface in water(H
2O) ambience was photochemically modified to be hydrophilic using an ArF excimer laser light. The hydrogen atoms of the surface, were pulled out by the hydrogen atoms which were photodissociated from H
2O and replaced with the OH radicals which were also photodissociated. The substitution of OH radicals was confirmed by the XPS and the contact angle measurement. Also, chemical bonding of the surface with epoxy adhesive was performed to obtain a shearing tensile strength of 9.5kgf/cm
2.
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SATOSHI INAZAKI, TOMONORI OIE, HIDETSUGU TAKAOKA
1994 Volume 7 Issue 2 Pages
389-396
Published: 1994
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PTFE surface property was modified from hydrophobicity to high wetting ability by ArF excimer laser irradiation in Monosodium L- Glutamate Monohydrate (L-Glutamate) solution and in ethyl alcohol solution. The wetting ability of the processed surface was examined by the water contact angle method. The contact angle of the film was improved from 120 degree to 0 degree. By XPS analysis it was shown that amino groups, carbonyl groups, ethylene linkages were substitutionally formed with the release of fluorine atom on the surface. These hydrophilic molecules formed on the processed surface are believed to make the surface hydrophilic. The processed surface showed its original appearance without any stain and physical damage. Spatial resolution of 1μm is obtained with this method.
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