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최재원,이한섭,김영호,Choi, Jae-Won,Lee, Han-Sup,Kim, Young-Ho 한국섬유공학회 2006 한국섬유공학회지 Vol.43 No.6
Poly(trimethylene terephthalate) (PTT)/poly(trimethylene naphthalate) (PTN) (50/50, weight ratio) blend films (T5N5) with amorphous state were prepared by melt-pressing of solution blended powders at $260^{\circ}C$ for various times and quenching them in liquid nitrogen. Homo PTT and PTN films were also prepared by the same method. Small angle X-ray scattering (SAXS) measurements during the heating process were carried out using synchrotron X-ray source to investigate the changes in microcrystalline structure of the PTT, PTN and T5N5 films. From the electron density correlation functions obtained from SAXS patterns, long period (L), lamella thickness ($I_c$), and amorphous layer thickness ($I_a$) were calculated. Long periods of the amorphous films began to increase at around crystallization temperature of the samples. The increase in both $I_c\;and\;I_a$ attributed to the increase of L.L of PTN film is larger than that of PTT. L of T5N5 exhibited values between those of PTT and PTN film and it increased with heat treatment time at $260^{\circ}C$.
백두현,지민호,이한섭,육지호,서승원,Baik, Doo-Hyun,Ji, Min-Ho,Lee, Han-Sup,Youk, Ji-Ho,Seo, Seung-Won 한국섬유공학회 2006 한국섬유공학회지 Vol.43 No.6
Segmented block copolyetherester (CPEE) solutions containing three kinds of nanoparticles were electro-spun and the resultant nanocomposite webs were characterized. Nano-sized clay, silica, and multi-walled carbon nan-otubes (MWNT) were used as nanoparticles and dichloromethane/trifluoro acetic acid (50:50, v/v) mixed solution was used as an electrospinning solvent. The FE-SEM analysis of the electrospun webs revealed that diameter of the nano-composite fibers was greater than that of pure CPEE. According to the FE-SEM results of the plasma-etched web, we knew that MWNT was aligned along fiber and silica particles were rather aggregated than being separated to the primary particles. DSC experiments indicated that electrospun web had higher melting temperature and heat of fusion than the film prepared from the same solution.
3-3'-Dimethyldiphenyl 4,4'-diisocyanate (TODI) 계 Polyurethane의 내부구조가 배향거동과 기계적 특성에 미치는 영향
김정호,이정상,이한섭,Kim, Jung-Ho,Lee, Jung-Sang,Lee, Han-Sup 한국섬유공학회 2005 한국섬유공학회지 Vol.42 No.2
New types of polyurethane (PU) have been synthesized using 3,3'-dimethyldiphenyl 4,4'-diisocyanate (TODI) in order to test the effect of the chemical structure of hard segment on the domain/segment deformation behavior and mechanical stability of polyurethane. The effect of hard segment (H/S) content on the domain/segment deformation behavior was measured with SAXS and FTIR-dichroism methods. For TODI-based PU of low H/S content, the long axes of individual hard domains of lamellar type were aligned along the uniaxial stretching direction. When the hard segment content increases, the hard domains form lamellar stacks and those stacks are either rotated or tilted towards the initial stretching depending on their H/S content. For polyurethanes of highest HIS content, the selective domain break-up phenomenon was found to be a major restructuring process. Segmental orientation behavior observed with FTIR-dichroism is consistent with domain deformation behavior observed with SAXS. Compared with MDI-based polyurethane, TODI-based polyurethane exhibits better mechanical stability and this is explained in terms of the good packing behavior of hard segments in the TODI-based polyurethanes.
Diisocyanate 및 Chain Extender의 화학적 구조가 폴리우레탄의 열적 특성에 미치는 영향
박기호,김광복,이한섭,Park, Ki-Ho,Jin, Gangfu,Lee, Han-Sup 한국섬유공학회 2008 한국섬유공학회지 Vol.45 No.2
Polyurethane(PU), a type of thermoplastic elastomer, consists of two different segments (hard and soft segments) that are incompatible at room temperature. Depending on the chemical and physical structure of those two segments, polyurethane shows various internal structures. In this study, a series of polyurethane were synthesized using PPDI (l,4-phenylene diisocyanate), TODI(3,3'-dimethyl diphenyl 4,4'-diisocyanate), MDI(4,4'-diphenylmethane diisocyanate) as disocyanate, 1,4 BD and HQEE(hydroxyquinone-di-(beta-hydroxyethyl)ether) as chain extender in order to test the effect of chemical structure of hard segment on the phase separation behavior and thermal stability of polyurethane. The effect of diisocyanate and chain extender on the thermal stability of polyurethane was measured with DSC, POM, SAXS and FTIR methods. Compared with PU based on the asymmetric and aliphatic component, PUs based on the symmetric and aromatic chemical structures were found to form phase separated structure showing enhanced thermal stability. The good thermal properties were also explained in terms of the good packing behavior between hard segments in the PPDI-based polyurethane.
중합방법의 차이가 PU/organoclay 나노복합체의 미세 구조 및 열적/기계적 특성에 미치는 영향
신나리,권병철,박기호,이한섭,Shin, Na-Ri,Kwon, Byung-Chol,Park, Ki-Ho,Lee, Han-Sup 한국섬유공학회 2007 한국섬유공학회지 Vol.44 No.1
Two different polymerization methods were used to synthesize the PU/organoclay nanocomposite by either 'one step addition' or 'two step addition' method. In two step addition method, the modified clay was reacted with isocyanate-terminated prepolymer to anchor the polymer chains to the silicate layers before the chain extension reaction occurred. On the other hand, the modified clay and chain extender were added simultaneously in the one step addition method. The effect of polymerization method on the exfoliated/intercalated structure of silicate layers as well as on the microphase separated structure of PU matrix has been studied with FTIR, SAXS and TEM methods. The PU/organoclay nanocomposite prepared with one step addition reaction showed better exfoliated structure which is effectively retarding the micro-phase separation process of PU. However, compared with two step addition one, one step addition method was more effective to enhance the initial modulus and tensile strength of the nanocomposites. The role of modified clay for the segmental orientation process was also studied by infrared dichroism method. The orientation process was hindered by the silicate layers and its effect was more pronounced in the nanocomposite by one step addition method.