• Fibers and Polymers
• /
• 제1권1호
• /
• pp.12-17
• /
• 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.

• 한국섬유공학회:학술대회논문집
• /
• 한국섬유공학회 1998년도 봄 학술발표회 논문집
• /
• pp.9-13
• /
• 1998

A number of papers concerning the preparation and physical properties of thermotropic polyurethanes have been reported,$^{1.2}$ since thermotropic polyurethanes were first reported by Iimura and coworkers.$^3$ We have been studying the synthesis of thermotropic para-type aromatic polyurethanes containing alkylene spacers.$^{4.7}$ .(omitted)

• Elastomers and Composites
• /
• 제34권4호
• /
• pp.292-298
• /
• 1999

Lactide oligomer with number averagae molecular weight of 460 was synthesized and reacted with poly(oxyteramethylene)glycol(PTMG, Mn = 650) to obtain oligolactide oligomer-terminated PTMG. Polyurethanes were synthesized from the oligolactide-terminated PTMG, 4,4'-diphenylmethane diisocyanate, and 1,4-butanediol. The mechanical and thermal properties of the polyurethanes and PTMG based polyurethane as control were measured by means of DSC and tensile tester. Degradation behavior of these polyurethanes put into a compost was evaluated by variation of mechanical properties, surface state, and weight loss. Modulus and weight significantly decreased with increasing time. The surface of the oligolactide polyurethane put into the compost during 6 weeks had a number of voids. On the other hand, These properties of the PTMG based polyurethane as control did not change. These results suggest that the novel polyurethanes incorporated oligolactide easily degrade under biodegradable condition.

• Macromolecular Research
• /
• 제16권3호
• /
• pp.194-199
• /
• 2008

Four novel polyurethanes were prepared from 4-{(4-hydroxyphenyl)iminomethyl} phenol by reactions with two aromatic diisocyanates, 4,4'-diphenylmethane diisocyanate and toluene 2,4-diisocyanate, and two aliphatic diisocyanates, isophorone diisocyanate and hexamethylene diisocyanate. The polyurethanes formed were characterized by UV-vis, fluorescence, FT-IR, $^1H$-NMR, $^{13}C$-NMR, differential scanning calorimetry, thermogravimetry, and X-ray diffraction. The polymers were semi-crystalline and all polymers were soluble in polar aprotic solvents.

• 폴리머
• /
• 제29권3호
• /
• pp.253-259
• /
• 2005

본 연구에서는 섬유의 구김을 방지하기 위해 첨가제인 폴리우레탄을 2단계 중합반응을 통하여 합성하였으며, 단계 반응 중합체의 구조와 합성된 폴리우레탄의 구조를 FT-IR과 $^1H-NMR$ 스펙트럼으로 확인하였다. 방향족 이소시아네이트인 4,4-diphenylmethane diisocyanate(MDI)로 합성한 폴리우레탄의 평균 분자량이 지방족 이소시아네이트인 hexamethylene diisocyanate(HDI), 4,4-dicyclohexylmethane diisocyanate($H_{12}$MDI)로 합성한 폴리우레탄의 분자량보다 크게 증가하였다. 또한 MDI, HDI, $H_{12}MDI$로 합성한 폴리우레탄의 유리전이온도($T_g$)는 각각 -25, -42, -50$^{circ}C$로 나타났다. 합성 폴리우레탄의 경질부분 함량이 증가함에 따라 열 안정성과 인장강도는 증가하였고, 파괴점에서의 연신율은 감소하였다.

• Bulletin of the Korean Chemical Society
• /
• 제26권5호
• /
• pp.841-844
• /
• 2005

• Bulletin of the Korean Chemical Society
• /
• 제29권4호
• /
• pp.811-816
• /
• 2008

2,5-Di-(2'-hydroxyethoxy)benzylidenemalononitrile (3) was prepared and polymerized with 2,4-toluenediisocyanate and 3,3'-dimethoxy-4,4'-biphenylenediisocyanate to yield novel T-type polyurethanes 4 and 5 containing 2,5-dioxybenzylidenemalononitrile, nonlinear optical (NLO)-chromophores as part of the polymer backbones. Polyurethanes 4 and 5 were soluble in common organic solvents such as acetone and N,Ndimethylformamide and showed a thermal stability up to $250{^{\circ}C}$ with glass-transition temperatures ($T_g$) in the range $119-146{^{\circ}C}$. The second harmonic generation (SHG) coefficients ($d_{33}$) of poled polymer films at 1064 nm fundamental wavelength were around $5.82{\times}10^{-9}$ esu. The dipole alignment exhibited high thermal stability up to $T_g$, and there was no SHG decay below $140{^{\circ}C}$ due to the partial main-chain character of the polymer structure, which was acceptable for nonlinear optical device applications.

• Elastomers and Composites
• /
• 제44권3호
• /
• pp.329-335
• /
• 2009

4종류의 새로운 형태의 열방성 액정폴리우레탄을 4,4'-Bis(5-hydroxypentoxy)biphenyl (BP5)와 2,6-tolylene diisocyanate (2,6-TDI), 2,5-tolylene diisocyanate (2,5-TDI), 및 2,4-tolylene diisocyanate (2,4-TDI), 1,4-phenylene diisocyanate (1,4-PDI) 의 중부가 반응에 의해 합성하였다. 단량체 BP5은 스멕틱상을 형성하였으며 1,4-PDI/BP5을 제외한 나머지 폴리우레탄에서는 모두 액정성을 나타내었다. 생성된 폴리우레탄의 구조는 FT-IR과 ^1H$ NMR 스펙트럼으로 확인하였고 열적 성질은 DSC와 편광현미경으로 관찰하였다.

• Macromolecular Research
• /
• 제14권3호
• /
• pp.373-382
• /
• 2006

A series of crosslinkable, waterborne polyurethanes (I-WBPUs) were prepared by in-situ polymerization using isophorone diisocyanate (IPDI)/poly(tetramethylene oxide) glycol (PTMG, $M_n$=2,000)/dimethylol propionic acid (DMPA)/ethylene diamine (EDA)/triethylamine (TEA)/aminoplast[hexakis(methoxymethyl)melamine (HMMM)] as a crosslinking agent. Typical crosslinkable, waterborne polyurethanes (B-WBPUs) blended from WBPU dispersion and aqueous HMMM solution was also prepared to compare with the I-WBPUs. The crosslinking reaction between WBPU and HMMM was verified using FTIR and XPS analysis. The effect of the HMMM contents on the dynamic mechanical thermal, thermal, mechanical, and adhesion properties of the I-WBPU and B-WBPU films were investigated. The storage modulus(E'), glass transition temperatures of the soft segment ($T_{gs}$) and the amorphous regions of higher order ($T_{gh}$), melting temperature ($T_m$), integral procedural decomposition temperature (IPDT), residual weight, $T_{10%}$ and $T_{50%}$ (the temperature where 10 and 50% weight loss occurred), tensile strength, initial modulus, hardness, and adhesive strength of both I-WBPU and B-WBPU systems increased with increasing HMMM content. However, these properties of the I-WBPU system were higher than those of the B-WBPU system at the same HMMM content. These results confirmed the in-situ polymerization used in this study to be a more effective method to improve the properties of the WBPU materials compared to the simple blending process.

• 한국염색가공학회지
• /
• 제7권4호
• /
• pp.8-15
• /
• 1995

A series of thermotropic Polyurethanes mesogenic unit were synthesized by polyaddition of a para-type diisocyanate such as 2,5-tolylene diisocyanate(2,5-TDI) with 4-4'-bis($\omega$-hydroxyalkoxy) biphenls(BPm: $HOCmH_{2m}OC_{6}H_{4}OC_{m}H_{2m}OH$ : m is the carbon number of the hydroxyalkoxy group) in DMF. Intrinsic viscosities of the polymers were in the range of 0.41~0.99dL/g DSC thermograms for these polymers exhibited two endothermic peaks corresponding to phase transitions of melting and isotropization. For examplem polyurethane 2,5-TDI/BPll with [η]=0.99 prepared from 2.5-TDI and 4,4'-bis[11-hydroxyundecaoxy biphenyl(BP11) a liquid crystalline phase from 156 to 173$^{\circ}C$. The thermotropic properites of liquid crystalline polyurethanes have been investigated by wide-angle X-ray scatter(WAXS), infrared (IR) spectroscopy, and differential scanning calorimetry (DSC). The mesomorphic behavior of the polyurethanes was concluded to be greatly dependent on the intermolecular hydrogen bonds through the urethane.