• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 1998년도 가을 학술발표회논문집
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• pp.203-206
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• 1998

열가소성 탄성체(Thermoplastic elastomers)의 일종인 polyurethane은 상온보다 높은 유리전이온도(T$_{g}$)를 갖는 hard segment(HS)와 낮은 T$_{g}$를 갖는 soft segment(SS)간의 열역학적 불친화성으로 인해 미세 상분리 구조를 갖는다. SS는 낮은 T$_{g}$로 인해 상온에서 rubbery한 성격을 나타내며 HS는 높은 T$_{g}$로 인해 물리적 가교 역할과 충진제 역할을 한다. Polyurethane은 중합당시의 조성이나 중합방법에 따라 다양한 내부구조를 갖으며 이런 내부구조의 변화에 따른 물리적 성질의 변화 역시 다양하다. (중략)

• 폴리머
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• 제25권1호
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• pp.33-40
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• 2001

불소화된 폴리우레탄 탄성체를 4,4'-diphenyl methane diisocyanate(MDI) 혹은 toluene 2,4-diisocyanate(TDI) 같은 diisocyanate와 perfluorinated polyether(Fomblin $ZDOL^{\circledR}$)로부터 2단계 용액 중합법에 의해 합성하였다. 합성된 폴리우레탄의 soft segment 부분 중 10~50%를 Fomblin ZDOL 성분이 되도록 polypropylene glycol(PPG) 혹은 polytetramethylene glycol(PTMG)과 같은 polyether polyol을 반응도중에 혼합하여 반응을 완성하였다. 사슬연장제로는 ethylene diamine 혹은 1,4-butanediol을 사용하였다. 합성 중합체의 확인과 평균분자량 등 특성조사에 FT-IR, $1^H$-NMR, 겔투과 크로마토그래피(GPC), 시차주사열량계(DSC)를 이용하였고 표면특성은 X-ray photoelectron spectroscopy(XPS)와 접촉각으로 조사하였다. 표면분석결과 불소기는 합성된 탄성체 필름의 내면보다 표면에 더 많이 분포함을 알 수 있었다

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 1996년도 추계 학술발표회
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• pp.465-467
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• 1996

A series of thermoplastic polyurethane copolymers were prepared from polypropyleneglycol(PPG, MW 3000), 1,4-butanediol, Isophorone diisocyanate(IPDI) and dibutyltin dilaurate(BBT) as catalyst. Studies have been made on the effects of molar ratio of isocyanate /polyol/chain extender on the properties such as tensile and thermal properties. By varying the ration of hard to soft segments, TPU ranging from soft elastomeric polymer to relatively hard elastoplastics and be obtained. The storage modulus and glass transition temperature of TPU increased with increasing the hard segment content.

• Elastomers and Composites
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• 제54권4호
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• pp.271-278
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• 2019

Polyurethane elastomers (PUEs) were synthesized using trans-1,4-bis(isocyanatomethyl) cyclohexane (1,4-H₆XDI), poly(oxytetramethylene) glycol, 1,4-butanediol (BD), and 1,1,1-trimethylol propane (TMP). To control the molecular aggregation state and mechanical properties of these PUEs, hard segment contents of 20 and 30 wt% and BD/TMP ratios of 10/0 and 8/2 were chosen. Differential scanning calorimetry and small-angle X-ray scattering measurements revealed that the degree of microphase separation increased with an increase in both hard segment content and BD ratio. The Young's modulus and strain at break of the 1,4-H₆XDI-based PUE were 6-20 MPa and 5-15, respectively. Incorporation of 20% TMP as a cross-linking agent into BD increased the melting temperature of the hard segment chains, that is, heat resistance, and decreased the Young's modulus. This could be due to the low density of the physical cross-linking network and the dispersion of hard segment chains in the soft segment matrix in the PUE in the presence of 20% TMP.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 1995년도 추계 학술발표회
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• pp.80-81
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• 1995

• Elastomers and Composites
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• 제27권3호
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• pp.161-173
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• 1992

A series of polyurethane block copolymers based on hydroxyterminated poly(dimethyl siloxane), poly(propylene glycol) and poly(tetramethylene glycol) soft segments of molecular weights 1,809, 2,000 and 2,000, respectively, were synthesized. The hard segments consisted of 4,4'-diphenylmethane diisocyanate and 1,4-butanediol as the chain extender. Samples with different molar ratios were prepared. We tried to synthesize poly(dimethyl siloxane)-based polyurethane(PDMS-PU) containing a hard block as major fraction and a soft block as minor fraction for preparing toughened rigid systems. After a study of the pure PDMS-PU, poly(propylene glycol)-based polyurethane(PPG-PU) and poly(tetramethylene glycol)-based polyurethane(PTMG-PU), (mixed polyol)-based block copolymers and blends between PDMS-PU, PPG-PU and PTMG-PU were prepared, and characterized by means of differential scanning calorimetry, tensile testing and scanning electron microscopy. In (mixed polyol)-based PU and in lower hard segment content blends, macro-phase separation was shown, but blends with higher hard segment contents showed significant reduction in amounts of phase separation.

• 대한치과교정학회지
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• 제28권6호
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• pp.975-979
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• 1998

하악 전치부 근첨하 골전단술을 동반한 상악 변형 분절골 절단술 목적은 양치조성 혹은 양악 전돌 환자로부터 가장 좋은 치료 결과를 얻는 것이다. 본 연구에서는 두부방사선 계측 분석과 정면 사진을 비교 분석해 술 후 연조직 변화를 조사하였다. 구순 전돌이 효과적으로 감소되었으며 비순각은 증가하였다. 코가 약간 넓어졌으나 결과는 비교적 양호하였다. 절단된 골분절의 혈액공급은 잘 유지되었다. 이것은 많은 환자에게 적용할 수 있는 비교적 간단한 수술법이다.

• 한국막학회:학술대회논문집
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• 한국막학회 1999년도 The 7th Summer Workshop of the Membrane Society of Korea
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• pp.23-26
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• 1999

Urethane block copolymers, containing soft segments such as polydimethylsiloxane (PDMS), polytertramethylene glycol(PTMG) and PEO-PPO-PEO (Poloxamer) block copolymer, were synthesized and examined for th vapor- phase separation of toluene from nitrogen stream by using vapor permeation equipment. Generally permeabilities of PTMG and PDMS based urethane membranes were higher than those of Poloxamer based urethane membranes. Organic vapor permeability in the PDMS and PTMG soft segment urethane membranes were greater than those measured in the Poloxamer films, due to more polymer swelling. The membranes performed best with toluene, with toluene/dry N2 seletivities ranging from 120~200 and permeablilities as high as 23$\times$10-9 mol/m2sPa for saturated toluene feeds at 23$^{\circ}C$.

• 폴리머
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• 제36권4호
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• pp.513-518
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• 2012

열적으로 안정한 탄화수소계 액상 파라핀인 YK-D130을 분산매로 사용하여 ${\omega}$-amino carboxylic acid와 adipic aicd로부터 폴리아미드 12(PA12) 올리고머(oPA1)를 제조하였으며 이들을 통상의 벌크중합으로 제조되는 비슷한 분자량의 폴리아미드 올리고머(oPA2)로 합성하여 분자량과 기타 특성을 비교하였다. 색도 분석 결과 oPA1이 더 밝은 백색을 나타냈고, GPC 결과로부터 oPA1가 더 좁은 분자량 분포를 보였다. 나아가 oPA1과 oPA2를 hard segment로 하고 poly(tetramethylene glycol)(PTMG)을 soft segment로 하는 탄성의 poly(ether-block-amide)(PEBA)를 합성하였다. 합성된 PEBA의 분자량과 기계적 성질 등을 비교 분석하였다.

• Journal of Korean Neurosurgical Society
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• 제60권1호
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• pp.30-39
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• 2017

Objective : To compare the clinical outcomes and biomechanical effects of total disc replacement (TDR) and posterior cervical foraminotomy (PCF) and to propose relative inclusion criteria. Methods : Thirty-five patients who underwent surgery between 2006 and 2008 were included. All patients had single-level disease and only radiculopathy. The overall sagittal balance and angle and height of a functional segmental unit (FSU; upper and lower vertebral body of the operative lesion) were assessed by preoperative and follow-up radiographs. C2-7 range of motion (ROM), FSU, and the adjacent segment were also checked. Results : The clinical outcome of TDR (group A) was tended to be superior to that of PCF (group B) without statistical significance. In the group A, preoperative and postoperative upper adjacent segment level motion values were $8.6{\pm}2.3$ and $8.4{\pm}2.0$, and lower level motion values were $8.4{\pm}2.2$ and $8.3{\pm}1.9$. Preoperative and postoperative FSU heights were $37.0{\pm}2.1$ and $37.1{\pm}1.8$. In the group B, upper level adjacent segment motion values were $8.1{\pm}2.6$ and $8.2{\pm}2.8$, and lower level motion values were $6.5{\pm}3.3$ and $6.3{\pm}3.1$. FSU heights were $37.1{\pm}2.0$ and $36.2{\pm}1.8$. The postoperative FSU motion and height changes were significant (p<0.05). The patient's satisfaction rates for surgery were 88.2% in group A and 88.8% in group B. Conclusion : TDR and PCF have favorable outcomes in patients with unilateral soft disc herniation. However, patients have different biomechanical backgrounds, so the patient's biomechanical characteristics and economic status should be understood and treated using the optimal procedure.