• Macromolecular Research
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• v.13 no.5
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• pp.418-426
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• 2005

One-pack cross-linkable nanocomposites of waterborne methyl ethyl ketoxime (MEKO)-blocked aromatic polyurethane dispersion (BPUD) reinforced with organoclay (quaternary ammonium salt of Cloisite 25A) were synthesized by the acetone process using 4,4'-methylenedi-p-phenyl diisocyanate (MDl), poly(tetramethylene) glycol (PTMG), dimethylol propionic acid (DMPA), and methyl ethyl ketoxime (MEKO). Particle size, viscosity, and storage stability of these nanocomposites were investigated. TEM and XRD studies confirmed that the silicate layers of organophilic clay were exfoliated and intercalated at a nanometer-scale in the BPUD matrix.

• Journal of Applied Reliability
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• v.17 no.3
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• pp.207-212
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• 2017

Purpose: This article provides an efficient cushion molding method for improving reliability of the rotation driving system. Method: Allowable stress level for cushion is calculated by using physical characteristics of the rotation driving system. In addition, various test units are manufactured and used to conduct the rebound resilience, the burst pressure and the alternating load test. Results: Actual allowable stress level and test results of the rebound resilience, the burst pressure and the alternating load test are provided. Conclusion: The cushion manufactured by the compression molding method gives more preferable characteristics for improving the reliability of the rotation driving system.

• Proceedings of the Korean Fiber Society Conference
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• 1996.10a
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• pp.468-472
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• 1996

A series of UV-curable polyurethane acrylate ionomer were synthesized from isophorone diisocyanate(IPDI), poly(tetramethylene ether glycol)(PTMG), 2,2-bis(hydroxymethyl)propionic acid (CMPA), triethylamine(TEA), 2-hydroxy ethyl acrylate (HEA), and dibutyl tin dilaurate (DBT) as a catalyst. 2,2-dimethoxy-2-phenyl acetophenone(DMPAP) was used as a photoinitiator. The films of UV-cured polyurethane acylate ionomer were prepared by casting the formulated materials onto a glass plate at room temperature and cured using a medium pressure mercury lamp (80 W/cm, max = 365nm). Effects of DMPA content, molecular weight of PTMG and degree of neutralization on the properties were invesigated. It is found that the storage modulus increased with increasing DMPA content. The glass transition temperature of sample A shifted to higher temperature as the content of DMPA was increased. Tensile modulus also increased with increasing DMPA content. Modulus and Tg decreased with increasing molecular weight of PTMG form 650 to 2000. With increasing the degree of nutralizaion, ionomers exhibited improved modulu.

• Macromolecular Research
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• v.10 no.6
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• pp.365-368
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• 2002

Thermoplastic polyurethanes (TPUs) with different hard segment length has been prepared from a fixed molar ratio of poly(tetramethylene ether glycol), 4,4'-diphenylmethane diisocyanate, and 1,4-butanediol by different polymerization procedures. Results reveal that the on-set temperature of endotherms ( $T_{cc}$ ) due to the crystallization of hard segments by cooling the TPUs from melt and the peak temperature of endotherms due to the melting of hard segments ( $T_{mh}$ ) by heating the TPUs increased and levelled off with increasing the hard segment length of TPUs. It has also been observed that soft segment glass transition temperature ( $T_{gs}$ ) of TPU decreased slightly with increasing the hard segment length, which explains less mixing of soft segments and hard segments. In tensile measurement of TPUs, strain hardening is observed with increasing the hard segment length, which is attributed to the strain induced crystallization of soft segments.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.5
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• pp.5-12
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• 2014

Weatherstrip coatings of urethane and silicon type which are fit to EPDM and thermoplastic materials are used in sealing systems for automotive applications for noise reduction and high slip characteristics for external applications, respectively. Polyurethane binder was successfully synthesized from poly(butyladiphate)diol (PBAD), poly(tetramethylene)glycol (PTMG) and isocyanate as starting materials. Then, polyurethane coating agents were prepared by using various additives. To investigate effects of segment types on the abrasion resistance of polyurethane coating agents, thin films based on polyurethane coating materials were fabricated. With increasing the amount of hard segment in the coating agent, abrasion resistance, modulus and tensile strength of the coating films were improved, but the elongation of the coating films was decreased.

• Applied Chemistry for Engineering
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• v.20 no.3
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• pp.258-265
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• 2009

An anionic polyurethane dispersions (PUDs) were synthesized from the poly (tetramethylene glycol) (PTMG, Mw = 2000 g/mol), mixed isocyanate of dicyclohexylmethane-4,4'-diisocyanate $(H_{12}-MDI)$ and 4,4'-diphenylmethane diisocyanate (MDI), and dimethylol propionic acid (DMPA) as anionic site, following a prepolymer mixing process. Triethylamine (TEA) was used as a neutralization agent and the ethylenediamine (EDA) as the chain extender of the prepolymer. The effects of the DMPA molar ratio and aromatic diisocyanate content in the mixed isocyanate on the particle size and viscosity of PUD were studied. Also, the mechanical and thermal properties of the PUD cast films were discussed according to the molar ratio of DMPA and aromatic isocyanate content. It was found that the particle size and the viscosity of an anionic PUD decreased with increasing DMPA molar ratio but increased with increasing aromatic isocyanate (MDI) content in the mixed isocyanate at the constant DMPA content. Tensile strength of the PUD cast films increased and elongation at break decreased with increasing DMPA content at the constant mixed isocyanate molar ratios. In thermal degradation temperature of PUD cast films, the effect of DMPA contents was great but the effect of aromatic isocyanate contents at the low DMPA content was very slight respectively.

• Applied Chemistry for Engineering
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• v.10 no.6
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• pp.913-916
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• 1999

Fluorine modified diisocyanate(FMD) was synthesized from tris(6-isocyanatohexyl)isocyanurate(TIHI) and N-ethyl-N-2-hydroxyethyl-perfluorooctanesulfonamide(HFA). Fluorine modified polyurethane(FMPU) was also synthesized from FMD and poly(tetramethylene) glycol(PTMG). Modified polyurethanes were made by blending FMPU into the polyester type base polyurethane(BPU). Surface and thermal properties of the blended BPU film was measured by contact angle measurement and DSC. As the amounts of FMPU was increased from 0 wt % to 1 wt %, the surface energy was dramatically decreased from 47.82 dyne/cm to 17.64 dyne/cm. But we observed little change of the contact angle with further increase in the amount of the FMPU up to 10 wt %. The data meant that the surface of the blended polyurethanes was hydrophobic due to the surface arrangement of the fluorine containing moiety in FMPU. Phase separation was induced by the incompatibility of FMPU and BPU for the samples having over 5 wt % of FMPU. The thermal analysis data of these samples showed the thermal behavior of the FMPU itself.

• Polymer(Korea)
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• v.38 no.5
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• pp.602-612
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• 2014

Polyurethanes containing poly(dimethyl siloxane) (PDMS) unit, PU-Si, were synthesized and their thermal and shape memory properties were investigated. Various amounts of PDMS units were incorporated via a solution polymerization method using mixed diols of poly(tetramethylene ether glycol) (PTMEG) and PDMS-diol as the soft segment (SS) and methylene diphenyl diisocyanate and 1,4-butanediol as the hard segment (HS). Two series of PU-Si samples with an HS content of 23% or 32% were prepared and analyzed. For PU-Si with an HS content of 23%, both the cold crystallization temperature ($T_{cc}$) and melt crystallization temperature of the SS domain moved higher temperature with increasing PDMS content, while the melting temperature ($T_m$) of the SS domain remained unaffected. The increase in HS content from 23% to 32% resulted in the increased $T_m$ and disappearance of $T_{cc}$. The shape recovery of PU-Si flim with an HS content of 32% increased while its shape retention decreased as PDMS content increased.

• Textile Coloration and Finishing
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• v.11 no.4
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• pp.1-7
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• 1999

Urethane-acrylate propelymers for secondary coating of optical fiber and high - performance material were prepared from the 4,4'-diphenylmethane diisocyanate(MDI), poly(tetramethylene oxide)glycol(PTMG, Mw 650 or 1000), 1,6-hexanediol(HD), 2-hydroxyethyl acrylate(HEA), and dibutyltin dilaurate as a catalyst. UV-Curable polyurethane acrylates were formulated from the urethane-acrylate prepolymers, three types of reactive diluents(DTs) having mono-, di-, and trifunctional-phenoxyethyl acrylate(PEA), hexanediol diacrylate(HDDA), and trimethylolpropane triacrylate(TMPTA), and 1-hydtoxycyclohexyl phenyl ketone(Irgacure 184) as a photoinitiator. The UV-cured films of polyurethane acrylates were obtained by curing using a medium-pressure mercury lamp(U W/cm, $\lambda_{max}=365\;nm)$. In this work, the effects of molecular weights of polyol and diol with low molecular weight into polymer chain on mechanical and dynamic mechanical properties of UV-cured polyurethane acrylates were studied. The structure and properties of the films obtained from the UV photopolymerization of urethane-acrylate prepolymer were investigated by FT-IR spectroscopy, dynamic mechanical measurement, tensile testing, and X-ray diffractometry.

• Polymer(Korea)
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• v.28 no.6
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• pp.538-544
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• 2004

Polyurethanes containing L-lysine segments in the main chain (PULL) were synthesized from 4,4'-diphenymethyl diisocynate, poly(tetramethylene glycol), and z-lysine oligomer as a chain extender. Insulin-immobilized polyurethanes (PULL-In) were prepared by a coupling reaction of PULL surface amino groups with insulins. The amount of immobilized insulin was about 0.30 nmol/$\textrm{cm}^2$, as determined by Bradford method. The interactions of NIH/3T3 fibroblasts with surface-modified PULLs were investigated using $^3$H-thymidine incoporation and optical microscopy. The cell growth rate on PULL-In film was higher than those on other substrates. The cell proliferation by the immobilized insulin was almost same as that by the free one.