• Applied Chemistry for Engineering
• /
• v.10 no.8
• /
• pp.1136-1140
• /
• 1999

Melt blends of polymide 6(PA6) and polypropylene grafted maleic anhydride(PP-g-MA) were prepared to study the influence of chemical reaction between the two polymer components. The tensile, flexural, izod impact, dynamic mechanical properties and phase structure were investigated for this blend system. Tensile strength and modulus of the blends showed synergetic effect upon blending of two polymer components. Flexural properties maintained the value of numerical mean calculated from the weight ratio of two components. Also, notched izod impact strengths showed maximum in th PA6/PP-g-MA 50/50 wt % blend. From the change of tan ${\delta}$ observed, we confirmed the increase of miscibility in this blend system by chemical reaction between PA6 and PP-g-MA. Blends of good impact resistance could be obtained when the PP-g-MA particles of $2{\mu}m$ was dispersed in the PA6 matrix.

• Rapid Communication in Photoscience
• /
• v.1 no.2
• /
• pp.27-29
• /
• 2012

Noble diamine monomers containing thiophene moiety were prepared, such as 2,5'''-diamino-2, 2':5', 2'':5'', 2'''-quaterthiophene (4TDA) and 2, 5'''''-diamino-3'', 4'''-dihexyl-2,2':5', 2'':5'', 2''':5''', 2'''':5'''', 2'''''-sexithiophene (6TDA). Then, these monomers were utilized to prepare polyimides with 3,6-diphenylpromellitic dianhydride (DPPMDA), 3,6-di(4'-trifluoro-methylphenyl) pyromellitic dianhydride (6FPMDA) or 3,6-di(3',5'-bis (trifluoromethyl)phenyl) pyromellitic dianhydride (12FPMDA) via a conventional two-step process. The polyimides were characterized by FT-IR, TGA and DSC, and then subjected CV, UV-vis and PL measurements. The polyimides containing thiophene moiety exhibited high glass transition temperatures ($280{\sim}310^{\circ}C$) and excellent thermal stability (> $420^{\circ}C$) in air as well as green emission (535~586 nm).

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.02a
• /
• pp.266-266
• /
• 2013

We show a set-up of poly (4,4'-aminotriphenylene hexafluoroisopropylidenediphthalimide) (6F-TPA PI)/Al sample in which holes are injected by photoelectron emission process instead of direct charge carrier injection via metal electrode. In this process, an irreversible electrical phase transition of 6F-TPA PI is found in contrast to the Al/6F-TPA PI/Al structure, leading to a write-once-readmany behavior. The photoelectron spectroscopy results measured before and after the switching process revealed that the irreversible electrical phase transition of 6F-TPA PI is attributed to the chemical modification of the carbonyl group in phthalimide moiety.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.50 no.4
• /
• pp.161-168
• /
• 2001

Organic thin film transitors(TFTs) are of interest for use in broad area electronic applications. For example, in active matrix liquid crystal displays(AMLCDs), organic TFTs would allow the use of inexpensive, light-weight, flexible, and mechanically rugged plastic substrates as an alternative to the glass substrates needed for commonly used hydrogenated amorphous silicon(a-Si:H). Recently pentacene TFTs with carrier field effect, mobility as large as 2 $cm^2V^{-1}s^{-1}$ have been reported for TFTs fabricated on silicon substrates, and it is higher than that of a-Si:H. But these TFTs are fabricated on silicon wafer and $SiO_2$ was used as a gate insulator. $SiO_2$ deposition process requires a high insulator which is polyimide and photo acryl. We investigated trasfer and output characteristics of the thin film transistors having active layer of pentacene. We calculated field effect mobility and on/off ratio from transfer characteristics of pentacene thin film transistor, and measured IR absorption spectrum of polymide used as the gate dielectric layer. It was found that using the photo acryl as a gate insulator, threshold voltage decreased from -12.5 V to -7 V, field effect mobility increased from 0.012 $cm^2V^{-1}s^{-1}$ to 0.039 $cm^2V^{-1}s^{-1}$ , and on/off current ratio increased from $10^5\;to\;10^6$. It seems that TFTs using photo acryl gate insulator is apt to form channel than TFTs using polyimide gate insulator.

• Polymer(Korea)
• /
• v.32 no.2
• /
• pp.125-130
• /
• 2008

A commercial cyclic diphosphonate ester (TPMP) and melamine (MA) was combined and added to polyamide 6 (PA6) to prepare the fire retardant PA6. An increase of the oxygen index to 28.6 as well as an improvement of the UL-94 classification to V-0 rating was observed. Cone measurements explained the rate of heat release (RHR) decreased and TGA showed the early decomposition and high solid residue due to co-addition of TPMP and MA, suggesting the occurrence of synergistic effect of TPMP and MA on fire resistance of PA6. The morphology of the char developed during combust ion showed the appearance of thick, intumescent cells on the surface of retardant PA6, which protects the underlying material from the action of the heat flux or flame and limits the diffusion of combustible volatile products towards the flame and oxygen.

• Journal of the Korean Vacuum Society
• /
• v.6 no.3
• /
• pp.187-193
• /
• 1997

We investigated the initial growth mode of Cu deposited on polyimide at room temperature using x-ray photoelectron spectroscopy. We could find that when Cu is sputter-deposited on the polymide, Cu-N-O complex of strong interaction is mainly formed first, Cu-oxide of weak interaction is formed successively, and then finally metallic Cu grow. From these results, we could conclude that Cu/polyimide interface consists of Cu-N-O complex and Cu-oxide.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.11 no.4
• /
• pp.306-313
• /
• 1998

To elucidate the liquid crystal(LC) molecules alignment mechanism, it is important to determine the molecular orientation of the rubbed polymer surface molecules that directly contact with LC molecules. In this work, the molecular orientation on a rubbed surface of polyimide (SE-3310, Nissan) film has been studied by polarized FTIR absorption spectroscopy. It has been found that molecular chain on the rubbed surface of polymide film are oriented along the rubbing direction and are tilted up on an average by 5.0$^{\circ}$. In the SHG(Second Harmonic Generation) measurement, the pretilt angle of molecular chain on the poylmide fim was 4.6$^{\circ}$ fro, the surface plane. And the pedit angle of liquid crystal (ZLI-2293, Merck) molecules measured by crystal rotation method was 5.4$^{\circ}$in the same rubbing condition.

• Journal of Photoscience
• /
• v.6 no.3
• /
• pp.109-115
• /
• 1999

Intense excimer laser irradiation of polymer films results in expansion and the following contraction , recovering ithe initial flat surface. The morphological dynamics is meausred directly by nanosecond time-resolved interferometry for polystyrene(PS), polyurethane, and polyimide films. The expansion proceeds with a speed of a few nm/ns , while the contraction depends upon the polymer ; very low contraction for PS, rapid 2 component shrinking for polyurethane, and rapid monotonous decay for polymide. These characteristic behavior are considered from viewpoints of interpenetrating structures of polymers, glass-rubber phase transitioni, thermal diffusion, and photothermal mechanism.

• Journal of Photoscience
• /
• v.6 no.3
• /
• pp.103-108
• /
• 1999

We present recent results on ablation mechanism, single-pulse laser micropatterning , pulsed-laser deposition(PLD) and particulates formation accompanying laser ablation, with special emplasis on polymers, in particular polymide, (PI), and polytetrafluoroethylene, (PTFE). Ablation of polymers is described on the basis of photothermal bond breaking within the bulk material. Here, we assume a first order chemical reaction, which can be described by an Arrhenius law. Ablation starts when the density of broken bonds at the surface reaches a certain critical value. Single-pulse laser ablation of polyimide shows a clear-length dependence of the threshold fluence. This experimental result strongly supports a thermal ablation model. We discuss the various possibilities and drawbacks of PLD and describe the morphology, physical properties and applications of PTFE films.

• Korean Journal of Materials Research
• /
• v.9 no.4
• /
• pp.355-361
• /
• 1999

We have synthesized the soluble polymide based side chain system with covalently attached NLO chromophore Disperse Red 1. The developed polymer is optically transparent in the range of optical communication wave-lengths. Its glass transition temperature$(T_g)$ and thermal decomposition temperature$(T_d)$ are $225^{\circ}C, 310^{\circ}C$ respectively. The poled film with the poling field of $100 V/\mu\textrm{m}$ shows that the dielectric constant is 3.37 at the 10-kHz frequency, the refractive indices of TM and TE modes are both 1.631 at $\lambda = 1300 nm$, and the Electro-optic coefficients are 4.6~9.2 pm/V at $\lambda = 1300 nm$. There are no decays of the EO coefficient in the poled polymer at $180^{\circ}C$ in one hour, and $90^{\circ}C$ in 500 hours.