• Journal of the Korea Institute of Military Science and Technology
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• v.12 no.5
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• pp.660-666
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• 2009

Thermoplastic polyurethane elastomer(PU-TPE) and energetic thermoplastic polyurethane Elastomer(E-PU-TPE) were prepared from Hexamethylene diisocyanate(HDI), 1,4-BD/AA ester polyol and glycidyl azide polymer(GAP-2400) as an energetic material by the addition polymerization. The PU-TPE and E-PU-TPE were characterized by FT-IR and GPC. Viscometer, DSC and UTM were used to investigate the viscose behavior with a various solvent, thermal properties and mechanical properties of PU-TPE and E-PU-TPE, which are of potential interest for the development of high performance binder of energetic solid propellants. It was found that $M_w$ of PU-TPE and E-PU-TPEs are over 100,000 and decreased with increase of GAP-2400 contents. $T_m$ and ${\Delta}H$ as thermal properties decreased and also tensile strength and elongation at break as mechanical properties decreased with increase of GAP-2400 contents.

• Korean Chemical Engineering Research
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• v.48 no.5
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• pp.615-620
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• 2010

In this study, five series of novel polyurethanes was synthesized by the polyaddition reaction of diisocyanates such as 2,6-tolylene diisocyanate(2,6-TDI), 2,5-tolylene diisocyanate(2,5-TDI), 2,4-tolylene diisocyanate(2,4-TDI), and 1,4-phenylene diisocyanate(1,4-PDI), hexamethylene diisocyanate(HDI) with 4,4'-Bis(3-hydroxypropoxy)biphenyl (BP3), 4,4'-bis(3-hydroxypropoxy)biphenyl exhibited a smectic type mesophase. Monotropic mesophase was found for all synthesized liquid crystalline polyurethanes except HDI/BP3. In contrast, 1,4-PDI/BP3 without a methyl substituent in the phenylene unit exhibited no explicit mesomorphic behavior, which was confirmed by DSC and polarizing microscopy experiments. Structures of the compound were identified by FT-IR and $^1H$-NMR spectroscopies. Their phase transition temperatures and thermal stability were also investigated by differential scanning calorimetry(DSC), polarized optical microscopy(POM) and x-ray diffraction analysis.

• Polymer(Korea)
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• v.29 no.3
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• pp.253-259
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• 2005

Polyurethanes, synthesized by polyester polyols and aliphatic or aromatic diisocyanates for a crease resist finishing agent, were prepared by two-step reactions, that is, prepolymer synthesis and chain extension. The structures of synthesized polyurethanes were confirmed by the measurement of FT-IR and $^1H$-NMR spectrometer. The number average molecular weight ($\bar{M}_n$) and the weight average molecular weight ($\bar{M}_w$) of the polyurethane with aromatic diisocyanate (MDI) were higher than those of the synthesized polyurethanes with aliphatic diisocyanate (HDI, $H_{12}MDI$). The glass transition temperatures ($T_g$) of soft segments in polyurethanes with MDI, HDI, $H_{12}MDI$ were -25,-42 and -50$^{circ}C$, respectively. In the polyurethanes obtained by two-step reaction, thermal stability and tensile strength increased with increasing hard segment contents, whereas elongation at break decreased with increasing hard segment contents.

• Textile Coloration and Finishing
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• v.25 no.1
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• pp.30-36
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• 2013

Swelling and subsequent deformation of membranes by water wetting are regarded as a prime drawback of hydrophilic polyurethane breathable film. Fluoroalkylated surface was prepared by reacting the film with hexamethylene diisocyanate(HDI) and 2-perfluorohexyl ethanol. IR spectra and XPS results showed that the fluoroalkyl group was successfully introduced to the film surface with hexamethylene linkage. Water contact angle was increased from $68.7^{\circ}$ up to $144.2^{\circ}$ with the degree of fluoroalkylation. Decrease in water-vapor permeability was minimized even for the film of highest fluoroalkylation.

• Polymer(Korea)
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• v.32 no.4
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• pp.340-346
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• 2008

The aim of this study is to understand the effect of structure on the dispersion of both CNT and GNF in the phase of synthesized polyurethanes matrix. Various CNT/PU and GNF/PU composite films were prepared. Polyurethane having a different hard segment was blended with both CNT and GNF. PU having HDI as hard segment showed good dispersion with both CNT and GNF because of their linear structural character and molecular kinesis while PU having aromatic ring showed poor dispersion with those due to their structural complexity. Structural effect also induced the increase of its electro conductivity. The PU/CNT composite showed a bad dispersion (because of phase separation between PU matrix and CNT) but good electro conductivity at its surface (because CNT was collected on the surface of composite film due to low density of CNT). PU/CNT and PU/GNF composite films have quite low normalized sheet resistance value compared with silver/PU nanocomposite film because the fiber type filler could have much more contact points than that of sphere shaped silver particles have.

• Macromolecular Research
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• v.13 no.3
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• pp.212-217
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• 2005

The pyrolysis kinetics of polyurethanes synthesized from polycaprolactone diol (PCL) and diisocyanate (HDI, $H_{12}MDI$) using catalysts such as dibutyltin dilaurate (DBTDL) were studied by a thermogravimetric (TG) technique, which involved heating the sample at the rates of 10, 20 and $30^{\circ}C$/min. The effect of the kind of diisocyanate and the hard segment contents on the activation energy and reaction order were examined at conversions ranging from 1 to $100\%$. The activation energies at first increased slowly with increasing conversion. Also, differential scanning calorimetry (DSC) was used to investigate the structural differences in each polyurethane. DSC can reveal the melting behavior, in terms of the glass transition temperature ($T_g$), which is known to vary as a function of the stoichiometry and processing conditions.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.4 no.2
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• pp.137-147
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• 1994

This study was designed to identify and quantitate airborne isocyanate simultaneously by HPLC. These samples were collected using 1-(2-pyridyl)piperazine(1-2PP) coated glass fiber filter from polyurethane painting works at 8 wood furniture factories in Kimpo and Inchun. The results obtained were as follows : 1. The most suitable mobile phase condition of simultaneously analyzing isocyanates was 0.01 M ammonium acetate buffer ACN(70/30) adjusted to pH 6.2 from the beginning of the analysis to 20 min and 0.01 M ammonium acetate buffer/ACN(50/50) adjusted to pH 6.2 from 21 min to 40 min using the gradient mode. The peaks of isocyanates were able to obtain within 30 min. 2. The recovery efficiencies for 2,6-TDI, 2,4-TDI, HDI and MDI urea derivates spiked at the target concentration on coated glass fiber tillers were 91.00, 93.42, 91.31 and 94.21 %, respectively. 3. The qualitative analysis of the isocyanates samples from polyurethane spray painting works in wood furnture factories identified Ihree isocyanates, 2,6-TDI, 2,4-TDI and MOI. And their concentration ranges were 0-312.6, 0-56.3 and $0-62.1{\mu}g/m^3$, respectively. A disadvantage of using the colorimetric method for isocyanate analysis is its inability of separating isocyanates. This study identified such three isocyanates as 2,6-TDI, 2,4-TDI and MDI from polyurethane spray painting works in wood furniture factories. These isocyanates were successfully quantitated by HPLC by modifying the mobile phase condition and switching to gradient mode.

• Textile Coloration and Finishing
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• v.15 no.5
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• pp.327-332
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• 2003

In this study, the polyurethane microcapsules for non-aqueous dyeing containing iron oxide and disperse dyes were prepared by in-situ polymerization method using hexamethylene diisocyanate(HDI) with ethylene glycol(EG). And the size, shape, and particle size distribution of microcapsules prepared were investigated. The size and shape of microcapsule were observed by optical microscope and scanning elecron microscope. The particle size distribution was analyzed by particle size analyzer. The microcapsule size and its distribution were largely effected by the existance of surface active agent in the system. When a surfactant did not exist in the system, the size distribution of microcapsules prepared was much uneven. By adding a surfactant, this phenomenon was disappeared. And the size of microcapsule was also effeced by the hydrophobicity of core material(disperse dye). It was considered due to the difference of dispersity of core materials. And the size of microcapsule prepared was inversely proportional to the stirring speed.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.160-161
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• 2021

To prepare polyurethane coatings for top coatings of automobiles, acrylic resins containing 75% of solids were synthesized by a radical polymerization. The viscosity of the acrylic resins was increased with increasing OH values. Crosslinked acrylic-urethane clear coatings were obtained by curing reaction between the synthesized acrylic resins and hexamethylene diisocyanate(HDI) trimer(Desmodur N-3600). The physical properties from the following studies were carried out : viscosity(Zahn cup #2), adhesion, pensil hardness, and 60° specular gloss. Various properties of the acrylic-urethane clear coatings as top coatings of mobile coat were evaluated on the coating specimens. Adhesion property to a substrate, 60° specular gloss, and pencil hardness of prepared paint showed quite good properties.

• Fibers and Polymers
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• v.1 no.1
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• pp.12-17
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• 2000

Thermotropic polyurethanes were synthesized from 1,6-hexane diisocyanate (HDI) as a diisocyanate, 1,6-hexane diol (HD), and rigid diols containing imide unit such as N,N＇-bis(4-hydroxyphenyl)-3,4,3＇,4＇-biphenyl-dicarboxyimide (BPDI) or bis-N-(4-hydroxyphenyl)-4,4＇-oxydiphthalimide (ODPI). The effects of structure difference between BPDI and ODPI and composition of HD/BPDl (ODPI) on the thermal and liquid crystalline behavior were studied. Thermotropic polyurethanes with an inherent viscosity of 0.59~0.70 were obtained. The melting temperature of BPDI-based polyurethanes were in the range of 150~$290^{\circ}C$, however, those of ODPI-based polyurethanes were in the range of 150~$190^{\circ}C$. All the polyurethanes based on ODPI (25~100 mole %) clearly exhibited a stable liquid crystalline phase, and BPDI-based polyurethane having 5-25% of BPDT showed a mesophase. The melting and isotropization temperatures ($T_m$, $T_i$) and ΔT($T_i$ - $T_m$) increased with increasing BPDI and ODPI content. The polyurethanes based on BPDI has higher melting points and thermal stability compared to ODPI-based polyurethanes.