3-Methylthiophene이 함유된 폴리우레탄 필름의 전기적 특성 연구

최교창 ( Kyo Chang Choi ),이은경 ( Eun Kyoung Lee ),최세영 ( Sei Young Choi ) 한국고무학회 2004 엘라스토머 및 콤포지트 Vol.39 No.3

본 연구에서는 poly(propylcne glycol) (PPG), toluene 2,4-diisocyanate, 3-methylthiophene (3-MT)으로부터 반응시간, FeCl₄의 농도, 3-MT와 PU의 무게비 반응온도 등의 다양한 조건에 따라 전도성 폴리우레탄 필름을 제조하였다. FeCl₃,와 ethy1 acetate로 구성된 유기용매에 제조한 필름을 함침 시킨 견과 3-MT와 FeCl₃의 확산-산화 반응을 통해 급속한 전도성 PMT 층이 형성되었다. 전도성 복합체의 전기 전도도는 제조조건에 따라 많은 영향을 받고 SEM 분석과 접촉카측정으로부터 반응시간과 반웅온도가 모폴로지와 표면 자유에너지에 미치는 영향을 조사하였으며 제조된 복합체의 전도도는 최대 42 S/cm 인 것으로 확인되었다. The clastomeric and conductive polyurethane (PU) films were prepared by poly(propylene glycol) (PPG). toluene 2,4-diisocvanate, 3-methylthiophenc (3-MT) at various preparation conditions, such as the reaction time, the FeCl₃ concentration, the weight ratio of the 3-MT to PU and the reaction temperature for the diffusion-oxidative reaction. The conductive poly (3-methylthiophene) (PMT) layers via the diffusion-oxidative reaction of 3-MT and ferric chloride were formed by immersing the film in organic solution of FeCl₃/ethyl acetate. The preparation conditions greatly affected the electrical conductivity of the 3-MT /PU composite. The effects of the reaction time and temperature on morphology and surface free energy were investigated by scanning electron microscopy (SEM) analysis and contact angle measurement, respectively. The conductivity of the composite was as high as 42 S/cm.

폴리에스터계 열가소성 탄성체의 합성 및 물성연구

최교창(Kyo Chang Choi),이은경(Eun Kyoung Lee),최세영(Seo Young Choi),박수진(Soo Jin Park) 한국공업화학회 2002 공업화학 Vol.13 No.1

본 연구에서는 dimethyl terephthalate (DMT), 1,4-butanediol (1,4-BD) 그리고 분자량이 2000인 polytetramethylene glycol (PTMG)로부터 용융중 합법을 이용하여 폴리에스터계 열가소성 탄성체를 제조하였다. 결정성 영역인 DMT 및 1,4-BD의 경질성 분절과 PTMG의 연질성 분절을 변량 배합하여 합성한 폴리에스터계 열가소성 탄성체는 다양한 물성을 나타내었으며 고온에서의 열적 안정성 및 기계적 물성을 증대시키기 위하여 열처리를 하였다. Differential scanning calorimeter (DSC) 분석 결과, 열처리된 시료의 경우, 융점이 보다 고온으로 이동된 것으로 보아 고온에서의 안정성을 확인할 수 있었다. 또한, 굴곡강도 및 탄성을 시험으로부터 연질성 분절의 함량이 35 wt%인 경우가 최적의 물리적 가교점을 형성함으로써 가장 우수한 기계적 물성을 나타내었고, scanning electron microscopy (SEM) 분석으로부터 연질성 분절의 함량이 증가할수록 결정성 부분의 감소로 인한 열적특성과 기계적물성을 예측할 수 있었다. In this work, the poly(ether-b-ester) thermoplastic elastomers (TPEEs) were synthesized by a melt polymerization, using dimethyl terephthalate (DMT), 1,4-butanediol (1,4-BD), and polytetramethylene glycol (PTMG) having the molecular weight of 2000 (g/㏖). The TPEEs prepared with hard segment, combination of DMT and 1,4-BD, and soft segment, PTMG, indicated a variety of properties. To improve thermal stability and mechanical properties at elevated temperatures, the final copolymers were produced by thermal treatment. Differential scanning calorimeter (DSC) showed that the melting points of the annealed TPEEs shifted to higher temperature zones than those of the unannealed ones, leading to a better understanding of thermal stability at elevated temperatures. Moreover, it was shown that the copolymer of 35 wt% content soft segment had the most significant mechanical properties for flexural strength and elastic modulus in flexure. The decrease of the crystallizable region with increasing the soft segment content, which was confirmed by scanning electron microscopy analysis (SEM) enabled us to estimate the thermal and mechanical properties.

마그네타이트가 충전된 NBR의 전기적 특성 및 물성 연구

최교창(Kyo Chang Choi),이은경(Eun Kyoung Lee),최세영(Sei Oung Choi),박수진(Soo In Park) 한국고분자학회 2003 폴리머 Vol.27 No.1

Fe3O4와 Chloroprene Rubber (CR)를 기초로한 탄성 전도체의 제조 및 특성연구

최교창 ( Kyo Chang Choi ),이은경 ( Eun Kyoung Lee ),최세영 ( Seo Young Choi ) 한국고무학회 2003 엘라스토머 및 콤포지트 Vol.38 No.1

본 연구에서는 FeCl_2 · 4H_2O, (CH_2)_6N_4 (hexamethylent tetramine) 그리고 NaNO_2로부터 Fe_3O_4 (magnetite)를 제조하고 결정성 CR고무에 배합하여 전도성 충전제의 함량이 물성에 미치는 효과와 전기전도도 (σ)의 온도 의존성을 조사하였다. 최소 최적 혼합비(percolation threshold, P_c) 개념이 본 연구에서 제조한 전도성 입자가 충전된 복합체에 적용되며, 혼합물내 Fe_3O_4의 분율이 27%를 초과할 때 전기전도도가 급격히 증가함을 확인하였다. 전기전도도의 온도 의존성은 P_c 또는 그 이하에서 열적으로 활성화되며 magnetite가 CR 고무의 강화 및 전도성 충전제로서의 역할을 할 수 있음을 조사하였다. 또한, 50 phr의 magnetite가 충전된 복합체가 최적의 물리적 가교점으로 인하여 가장 우수한 인장강도와 파단시 신장율을 보였으며 모듈러스가 magnetite의 강화효과 및 블랜드물의 가황 토오크 곡선으로부터 얻은 점도와 관련이 있음을 확인하였다. In this work, Fe_3O_4 (magnetite), conductive filler was prepared from FeCl_2 · 4H_2O, (CH_2)_6N_4 (hexamethylent tetramine), and NaNO_2, followed by mixing with crystallizable chloroprene rubber(CR). The influence of conductive filler content on the properties of the conductive composite was studied and temperature dependence of the electrical conductivity (σ) was also investigated. It is found that the percolation threshold concept holds true for the conductive particle-filled composite where σ indicates a nearly sharp increase when the fraction of magnetite in the mixture exceeds 27%. The temperature dependence of σ is thermally activated blelow or at the P_c. Magnetite acts as reinforcement and conductive filler for CR rubber. Moreover, it is shown that the composite with magnetite of 50 phr gives the most significant mechanical properties for tensile strength and elongation at break, which is due to the formation of optimum physical interlock and crosslinking. The results of 100%, 200%, and 300% moduli suggest that the moduli are related with reinforcement effect of magnetite and viscosity of the blend.

Poly(glycolide-co-$\varepsilon$-caprolactone) 공중합체의 합성 및 특성 분석

박남집,지민호,송승호,안상국,최교창,백두현,Park, Nam-Jib,Jee, Min-Ho,Song, Seung-Ho,Ahn, Sang-Kook,Choi, Kyo-Chang,Baik, Doo-Hyun 한국섬유공학회 2010 한국섬유공학회지 Vol.47 No.1

Poly(gylcolide-co-$\varepsilon$-caprolactone)(PGCL) was synthesized by bulk ring-opening polymerization of glycolide and $\varepsilon$-caprolactone using stannous octoate as a catalyst. Polymerization was conducted at a constant molar ratio of glycolidel-$\varepsilon$-caprolactone (55/45). The changes of copolymer chain structure according to the reaction conditions such as reaction time, temperature and catalyst feed ratio were studied by using $^1H$-NMR spectroscopy. The effects of reaction time and catalyst feed ratio on the chain microstructure of the final PGCL copolymers were found to be significant. The average sequence length of glycolyl segments in the copolymer decreased with transesterification during polymerization, which made PGCL microstructure more random.

Poly(glycolide-co-${\varepsilon}$-caprolactone) 블록 공중합체의 합성과 비등온 결정화 거동 분석

최송연,지민호,박남집,송승호,최교창,백두현,Choi, Song-Yeon,Jee, Min-Ho,Park, Nam-Jib,Song, Seung-Ho,Choi, Kyo-Chang,Baik, Doo-Hyun 한국섬유공학회 2011 한국섬유공학회지 Vol.48 No.1

Poly(glycolide-co-${\varepsilon}$-caprolactone)(PGCL) block copolymers were synthesized by two step polymerization using glycolide and ${\varepsilon}$-caprolactone as starting materials. The chain-microstructures of the resulting block copolymers were characterized by $^1H-NMR$. The structure and thermal properties of the PGCL block copolymer were strongly affected by the chain-microstructure of the prepolymer. The non-isothermal crystallization behavior of the PGCL block copolymers was examined at various cooling rates and analyzed with modified-Avrami and Ziabicki equations. The PGCL block copolymer with a lower degree of randomness in the prepolymer block had a higher crystallization temperature and faster crystallization rate, which suggests that differences in chain-microstructure of the PGCL prepolymer can affect the crystallization characteristics, such as crystallinity and crystallization rate.

발포온도와 카본블랙 함량이 천연고무 발포체의 가황거동 및 발포특성에 미치는 영향

김준형 ( Joon Hyung Kim ),최교창 ( Kyo Chang Choi ),윤진민 ( Jin Min Yoon ),김수연 ( Soo Yeon Kim ) 한국고무학회 2006 엘라스토머 및 콤포지트 Vol.41 No.3

본 연구에서는 발포체의 가황거동과 발포특성에 발포온도 및 카본블랙 함량이 미치는 영향을 조사하기 위해 카본블랙을 변량 배합하고 145℃에서 165℃까지 5℃ 간격으로 발포하여 천연고무 발포체를 제조하였다. 발포온도 및 카본블랙 함량이 증가함에 따라 t(s2) 그리고 t(90)의 감소 경향이 관찰되었다. 본 연구에서 천연고무의 발포 가황특성의 최적 온도는 165℃ 였으며 이때 발포된 천연고무 밀도가 가장 낮은 것으로 확인되었다. 145℃에서 발포된 천연고무 발포체의 가교속도지수가 가장 작은 값을 보였다. 발포 천연고무의 발포 및 모폴로지 특성으로부터 발포체의 밀도 특성을 확인할 수 있었다. 고무내부에 생성된 각 발포 격벽의 두께는 발포 온도가 증가함에 따라 감소하는 반면 카본블랙 함량 증가와 더불어 증가함을 보였다. To investigate the influence of the foaming temperature and carbon black content on the cure behaviors and foaming characteristics of the foams, natural rubber (NR) was foamed at five temperature zones (145, 150, 155, 160 and 165℃) and different feeding ratios of the carbon black. A decreasing trend of the scorch time, t(s2) and cure time, t(90) was observed upon increasing foaming temperature and carbon black content. The optimal temperature for vulcanization and foaming of NRs in this study was considered to be 165℃ where density of the foamed NRs is lower than those at other four temperature regions. The cure rate index of the NRs foamed at 145℃ is smaller than those at 150, 155, 160 and 165℃. The results of the expansion ratio and micrographs of the foamed NRs were founded to support the density characteristics. The thickness of each of the struts formed inside the rubber matrix decreases with increasing the foaming temperature, while it increases with increasing the carbon black content.

이원중합형 코어레진의 개발 및 평가

김형식(Hyoung-Sik Kim),송부석(Bu-Seok Song),최교창(Kyo-Chang Choi),이용근(Yong-Keun Lee),김경남(Kyoung-Nam Kim),김광만(Kwang-Mahn Kim) 대한치과재료학회 2012 대한치과재료학회지 Vol.39 No.2

Poly(ether-b-ester) Thermoplastic Elastomers : Synthesis and Properties

Choi, Sei Young,Choi, Kyo Chang,Lee, Eun Kyoung 청주대학교 산업과학연구소 2001 産業科學硏究 Vol.18 No.2

디메틸 테레프탈레이트 (DMT), 1,4-부탄디올 (1,4-BD) 그리고 분자량이 2000인 폴리테트라 메틸렌에테르 글리콜 (PTMG)로 부터 폴리에스터계 열가소성 탄성체 (TPEE)를 합성할 수 있었다. 고온에서의 열적 안정성및 기계적 물성을 증대시킬 목적으로 열처리를 하였으며, 이에 따라 결정성 hard segmen의 보다 규칙적인 배열로 인한 향상된 물성을 확인 할 수 있었다 본 실험에서 합성된 공중합체는 soft segment의 함량이 증가함에 따라 융점및 결정화도가 감소함을 보여 주었다. 기계적 물성의 경우, soft segment의 함량이 35%인 공중합체가 soft segment와 hard segment간 최적의 물리적 가교점 형성으로 인하여 가장 우수함이 관찰 되었다. The poly(ether-b-ester) thermoplastic elastomers (TPEEs) were synthesized by melt polymerization using dimethyl terephthalate (DMT), 1,4-butanediol (1,4-BD) and poly (tetramethylene ether) glycol (PTMG) in the molecular weight of 2000 (g/㏖). The copolymers were prepared with a constant PBT mass ratio of 100; the content of PTMG was changed. To improve thermal stability at elevated temperatures and mechanical properties, the final copolymers were annealed. The chemical structure and thermal properties of them were examined by utilizing FT-IR and DSC. For a better understanding of the structure and property relationships, SEM and a three-point loading system (UTM) were used. The rheological characteristics of them involving the changes of viscosity with the increasing shear rate were also studied. From this experiment, it was shown that as the proportion of soft segment increases melting temperature and degree of crystallinity of TPEEs decrease constantly and the lamella structure was found to be less fine in shape. Meanwhile, in case of flexural strength and flexural elastic modulus, 35-PTMG^(2000) indicates the highest values. As the shear rate increases thixotropy (shear thinning), one of the non-newtonian flows, is found. The results of melt flow properties seem tc be similar to those of strength and elastic modulus in flexure, and 35-PTMG^(2000) shows the viscosity higher than others. A11 of the properties of the copolymers synthesized in this work were found to be improved by thermal treatment.

유화 Chlorosulfonated Polyethylene Rubber (CSM)의 제조 및 특성 연구

이은경,최교창,최세영 한국고무학회 2005 엘라스토머 및 콤포지트 Vol.40 No.1

본 연구에서는 CSM 에멀젼의 물성을 향상시키고자 금속성 가교제인 magnesium carbonate 및 calcium hydroxide를 첨가하여 가교밀도, 열적특성, 표면자유에너지 그리고 인장강도, 파단신율 및 인열강도 특성을 고찰하였다, 금속성 가교제인 magnesium carbonate 및 calcium hydroxide 양이 증가함에 따라 CSM 에멀젼 필름은 가교밀도는 증가하였고, 이에 내수성과 T_(g) 값도 증가하였다. 금속성 가교제로 magnesium carbonate를 첨가하였을 때 calcium hydroxide에 비해서 다소 높은 가교밀도와 T_(g) 값을 보였다. 하지만 CSM 에멀젼 필름의 표면에너지 및 기계적 특성들은 다소 다른거동을 보였다 Magnesium carbonate 0.75% 그리고 calcium hydroxide 1.0% 첨가한 경우가 가장 높은 표면 자유에너지 값과 인장강도 및 인열강도를 보였으나, 그 이상의 양을 첨가하였을 경우에는 오히려 감소함을 확인하였다. 그러므로 본 연구에서 CSM 에멀젼의 물성을 향상시키는데 적용되는 금속성 가교제로서 calcium hydroxide 보다 magnesium carbonate가 더 적당하며, 0.75% 첨가하였을 때 보다 향상된 물성을 얻을 수 있었다. In this work. magnesium carbonate and calcium hydroxide as metallic crosslinking agent were added to chlorosulfonated polyethylene rubber (CSM) emulsion to enhance the mechanical properties of emulsion film such as tensile strength. elongation at break, and tear strength and crosslinking density. thermal features, and surface energy were also investigated. Crosslinking density of the CSM emulsion film with increasing the amount of magnesium carbonate and calcium hydroxide increased. leading to the enhancement of water resistance. It was shown that compared with calcium hydroxide, magnesium carbonate had a little higher crosslinking density and To value. The surface energy and mechanical characteristics of the CSM emulsion film, however, showed somewhat different behaviors. The highest surface energy. tensile strength. and tear strength were observed when 0.75° o for magnesium carbonate and 1.0° o for calcium hydroxide were added respectively. Therefore. it can be concluded that as metallic crosslinking agent to improve water resistance and mechanical properties of the CSM emulsion, magnesium carbonate is more preferable to calcium hydroxide