• Macromolecular Research
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• 제10권4호
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• pp.230-235
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• 2002

Alternating polyols of oxymethylene and oxyalkylene were synthesized and used as precursors for thermoplastic poly(ether-ester) elastomers (TPEs). The polyols were synthesized by reacting diols having different methylene units with dichloromethane in the presence of a phase transfer catalyst. The number of methylene units in the alkylene oxides was varied from 3 to 6. TPEs were prepared using the polyols as soft segments and poly(butylene terephthalate) units as hard segments. The polyols and TPEs synthesized were characterized using FTIR, NMR, GPC, DSC, and polarized optical microscopy. The polyols showed a profound odd-even effect on the melting (T$_{m}$) and glass transition temperatures (T$_{g}$). Polyols with odd numbers of methylene groups in the alkylene units have higher transition temperatures than polyols with odd number of methylene groups. The tendency is still kept in TPEs, even though the T$_{g}$ of soft segment in TPEs are slightly higher than those of corresponding neat polyols. The T$_{m}$ and T$_{g}$ of soft segments are almost constant in the range of 20 to 60 wt % contents of soft segments. On the other hand, the normalized heat of fusion of hard segment decreased with increasing the content of loft segment.ent.t.ent.

• 한국연초학회지
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• 제15권2호
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• pp.111-114
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• 1993

This study was carried out to obtain the basic information for breeding of aromatic burley tobacco, and to select the breeding lines with higher DVT (diterpenes $\alpha$-and $\beta$-4, 8, 13-duvatriene-1, 3-diols) and cis-abienol (Z-labda-12, 14-diene-8$\alpha$-ol) concentrations. The parental genotypes used to develop the Fl and Fl generations were Burley 21, Ky 17, male-sterile(MS) NC 107, TC 612, TC 613, Va 509 and Tl 1068. To estimated the modes of inheritances of DVT and cis-abienol known as the flavor and aroma compounds, the method of thin - layer chromatography (TLC) was used. It was considered that TLC procedure being relatively simple and reproducible in the selection of the breeding lines with higher DVT and cis-abienol. DVT was present in all of parents except MS NC 107, but cia-abienol presented only in Tl 1068. It was estimated from the TLC analysis of parents and Fl's that DVT and cis-abienol were each inherited by dominant gene or genes. But it was less clear to determine the presence or not of sucrose ester(SE) on the TLC plate. The eleven plants which had burley leaf color and also estimated to have DVT and cis-abienol were selected in the F2 population of three combinations.

• Bulletin of the Korean Chemical Society
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• 제18권8호
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• pp.890-895
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• 1997

The approximate rates and stoichiometry of the reaction of excess lithium tripiperidinoaluminum hydride (LTPDA), an alicyclic aminoaluminum hydride, with selected organic compounds containing representative functional groups under the standardized conditions (tetrahydrofuran, 25°) were examined in order to define the reducing characteristics of the reagent for selective reductions. The reducing ability of LTPDA was also compared with those of the parent lithium aluminum hydride (LAH) and lithium tris(diethylamino)aluminum hydride (LTDEA), a representative aliphatic aminoaluminum hydride. In general, the reactivity of LTPDA toward organic functionalities is weaker than LTDEA and much weaker than LAH. LTPDA shows a unique reducing characteristics. Thus, benzyl alcohol, phenol and thiols evolve a quantitative amount of hydrogen rapidly. The rate of hydrogen evolution of primary, secondary and tertiary alcohols is distinctive. LTPDA reduces aldehydes, ketones, esters, acid chlorides and epoxides readily to the corresponding alcohols. Quinones, such as p-benzoquinone and anthraquinone, are reduced to the corresponding diols without hydrogen evolution. Tertiary amides and nitriles are also reduced readily to the corresponding amines. The reagent reduces nitro compounds and azobenzene to the amine stages. Disulfides are reduced to thiols, and sulfoxides and sulfones are converted to sulfides. Additionally, the reagent appears to be a good partial reducing agent to convert primary carboxamides into the corresponding aldehydes.

• Elastomers and Composites
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• 제58권2호
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• pp.70-80
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• 2023

The effect of phenylphosphonic acid (PPOA) on polyurethane (PU) thermal stability was studied through Fourier transform infrared spectroscopy and Thermogravimetric analysis. To synthesize PPOA-modified PUs (PPOA-PUs), polyether-type diols (Mw=62, 106, 190, 419, 605) were chemically modified with PPOA and then reacted with 4,4'-dicyclohexylmethane diisocyanate (H₁₂MDI) and 4,4-diphenylmethane diisocyanate (MDI). During thermal decomposition in air, the PPOA embedded in the PUs formed intumescent phosphocarbonaceous char. Below 400℃, PPOA-H₁₂MDI-PUs were more unstable, as PPOA decomposed at lower temperatures than phenyl groups and aliphatic ethers. Above 550℃, the thermal stability of PUs followed this order: PPOA-MDI-PUs > PPOA-H₁₂MDI-PUs > MDI-PUs > H₁₂MDI-PUs. At 700℃, unmodified PUs had no residue, while the PPOA-MDI-PU residue was 4.4~23.0 wt.% and the PPOA-H₁₂MDI-PU residue was 1.5~17.5 wt.%. The enhanced thermal stability of PPOA-MDI-PUs at high temperatures can be attributed to the synergetic effect of PPOA and phenyl groups on the formation of phosphocarbonaceous char.

• 공업화학
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• 제7권2호
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• pp.341-349
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• 1996

폴리우레탄 수지의 염색성을 향상시키기 위하여 염착좌석을 갖는 저분자량의 디올류를 쇄연장제로 활용하였다. 쇄연장제와 폴리올의 종류를 변화시키고, 또한 하드세그멘트 (HS)/소프트세그멘트 (SS) 비율을 변화시키면서 폴리우레탄 수지를 합성하였다. HS/SS가 1.4이고, dimethylolpropionic acld(DMPA), N-butyldiethanolamine(BDEA)를 염착좌석용 쇄연장제(DCE)로 활용한 경우 반응의 불균일성으로 인하여 기계적 물성이 좋지 못하였으며, 특히 에스테르계 폴리올인 poly(butylene/ethylene adipate) glycol(PBEAG)로 합성한 경우 내가수분해성이 현저히 저하되었다. 그러나 DCE로 N-methyldiethanol amine(MDEA)를 사용하고 HS/SS를 1.3으로 조절한 경우 기계적 물성과 염색성이 향상되었으며, MDEA를 선형 쇄연장제(CE)인 1,4-butanediol(1,4-BD)과 에테르형 폴리올인 poly[oxyteramethylene] glycol(PTMG)과 반응시킨 경우 기계적 물성과 내가수분해성이 현저하게 향상되었다. 특히 분자설계적 측면에서 DCE를 HS와 SS내의 배분과 1,6-hexanediol(1,6-HD) 및 neopentylglycol(NPG)과의 공쇄연장으로 초기탄성률, 인장강도, 신장률을 제어 할 수 있음을 알 수 있다.

• 공업화학
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• 제10권1호
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• pp.93-97
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• 1999

불포화폴리에스테르 수지의 표면에너지를 저하시키기 위하여 실록산-에스터 공중합체를 소량 첨가하였다. 실록산-에스터 공중합체는 diol로써 ethylene glycol(EG)과 hydroxy terminated polydimethylsiolxane(PDMS)을, diacid로써 maleic anhydride (MA)와 phthalic anhydride (PA)를 축중합반응 시켜 합성하였다. 경화된 블렌드의 표면성질은 동적접촉각(dynamic contact angles)측정, 점착테이프의 peel 강도측정 및 X-ray photoelectron spectroscopy (ESCA)등을 통하여 분석하였다. 블렌드에서 공중합체의 첨가량이 증가하고, 공중합체내의 PDMS 함량이 증가함에 따라 물에 대한 advancing 접촉각 및 receding 접촉각이 증가하였으며, 점착테이프의 peel 강도는 급격히 감소하였다. ESCA 분석결과 실록산 세그멘트가 공기쪽 표면층에 주로 존재하고 있음을 알 수 있었다.

• 폴리머
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• 제29권2호
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• pp.140-145
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• 2005

열가소성 폴리우레탄(thermoplastic polyurethane: TPU)의 제조에 사용한 폴리올 종류와 경질부 함량에 따른 TPU의 결정화 거동을 고찰하였다. TPU의 제조에 사용한 폴리올은 분자량이 2000인 poly(tetamethylene ether glycol) (PTMEG), poly(propylene glycol)(PPG) diol, polycaprolactone(PCL) diol, poly(butylene adipate)(PBA) diol을 사용하였으며, 경질부 함량은 $35\~44\;wt\%$였다. TPU의 경질부 냉각 결정화는 경질부 함량이 많을수록 고온에서 관찰되었다. TPU의 등온 결정화 속도는 경질부 함량이 많을수록 빠르고, TPU 제조에 사용한 폴리올 종류별로는 $PTMEG>PPG>PCI{\geqq}PBA$ 경향이 나타나, 연질부와 경질부의 상용성이 낮을수록 용융상태에서 경질부의 수소결합이 용이하고 결정화 속도가 빠르며, 냉각 결정화가 고온에서 나타나는 것으로 해석하였다.

• Macromolecular Research
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• 제12권2호
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• pp.195-205
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• 2004

We have synthesized new aromatic polyesters (DiPEG-HQ and DiPEG-BP) by condensation polymerization of a terephthalic acid derivative bearing a pendant oligo(oxyethylene) (DP = 7, MW = 350), which has a methoxy terminal group, and two different aromatic diols, hydroquinone and 4,4'-biphenoI. The synthesized polymers were characterized by differential scanning calorimetry (DSC), polarizing microscopy, and X-ray diffractometry for their liquid crystallinity (LC), thermal transitions, and structural morphologies in mesophases. The morphology of the LC phases depends strongly on the length of the rigid backbone repeating unit. The DiPEG-BP polymer having a longer repeating unit exhibits both layered and nematic structures before isotropization, whereas the DiPEG-HQ polymer having a shorter repeating unit shows only the layered structure in the mesophase. We found that the layer spacing for DiPEG-HQ is larger than that for DiPEG-BP. Both polymers easily form complexes with LiCF$_3$SO$_3$; we studied this complex formation by FT-IR spectroscopy. The layer spacing of the polymer-electrolyte composites increases upon increasing the amount of the lithium salt. The polymer/salt electrolyte mixtures we investigated at molar ratios of EO:salt in the range of 5-20 exhibit electrical conductivity values at 40$^{\circ}C$ of 2.4${\times}$10$\^$5/ and 1.1${\times}$10$\^$－5/ S/cm for DiPEG-HQ/LiCF$_3$SO$_3$ and DiPEG-BP/LiCF$_3$SO$_3$, respectively. At 80 $^{\circ}C$, these values are higher: 4.6${\times}$10$\^$－3/ and 1.1${\times}$10$\^$－4/ S/cm, respectively. The activation energy of conductivity depends strongly on the salt concentration.

• 폴리머
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• 제34권6호
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• pp.507-510
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• 2010

이산화탄소와 에폭사이드를 크롬계 전이 금속촉매를 이용하여 교대 공중합하여 poly(cyclohexane carbonate) diol(PCCD)을 분자량 별로 제조하였다. 이산화탄소를 기반으로 한 폴리카보네이트(PCCD)의 응용분야 탐색을 위하여 수분산 폴리우레탄(PUD) 제조를 위한 전구체로 적용하여 보았다. 상업화되어 사용중인 폴리카보네이트 디올과 신규 PCCD로 제조한 PUD의 내스크래치 특성과 열적 특성을 비교 분석하였다. PCCD를 사용하여 제조된 PUD 필름의 내스 크래치성과 열분해온도는 PCD를 사용한 경우보다 떨어지지만, 유리전이온도는 증가하는 것을 알 수 있었다. 이것은 PCCD의 강직한 사이클로 헥산 구조에 기인한 것으로 생각된다.

• Applied Biological Chemistry
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• 제29권2호
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• pp.198-206
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• 1986

정제인삼(精製人蔘)사포닌의 수용액을 분자투석막(分子透析膜)(분자량(分子量) 12000)을 통(通)하여 투석(透析)하거나 Bio-Gel P-2(분자량(分子量) $200{\sim}2000$)gel을 통과시켜 분취(分取)하고 HPLC로 ginsenoside를 분석(分析)하였다. Ginsenoside는 분자결합양상(分子結合樣相)과 분자내(分子內) 친수성기(親水性基)의 공간배열(空間配列)에 따라 3군(群)으로 분류(分類)되었다. 제(第) I 군(群)은 거대(巨大)미셀 형성자(形成者)로 결합분자수(結合分子數)가 10이상이며 I면친수기형(面親水基形)이고 panaxadiol인 $Ginsenoside\;Rb_1$, $Rb_2$, Rc 및 Rd가 포함된다. 제(第)II군(群)은 소(小)미셀형성자(形成者)로 결합분자수(結合分子數)가 10이상(以上)에서 1까지이고 불완전(不完全) 양면친수기형(兩面親水基形)이며 triol인 $Rg_2$와 Rf 및 diol인 $Rg_3$가 포함된다. 제(第)III군(群)은 단분자(單分子)로 존재(存在)하며 양면친수기형(兩面親水基形)이고 triol인 Re와 $Rg_1$을 포함한다.