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- 저자 : 전옥철(Ok Cheol Jeon) (검색결과 4 건)
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곁사슬에 ethoxy 그룹을 갖는 열방성 액정폴리에스테르와 폴리 ( 에틸렌 2,6 - 나프탈레이트 ) 와의 블렌드
전옥철(Ok Cheol Jeon),최재곤(Jae Kon Choi),조병욱(Byung Wook Jo) 한국공업화학회 2002 공업화학 Vol.13 No.3
결사슬에 ethoxy 그룹을 갖는 열방성 약정고분자(TLCP)를 합성하였으며, 이를 폴리(에틸렌 2,6-나프탈레이트)(PEN)와 용액블렌딩하였다. 합성된 액정중합체는 nematic상을 보여 주었다. 제조된 블렌드(2, 5,10 and 20 wt% TLCP/PEN)의 열적, 동적·기계적 성질 그리고 모플로지를 조사하였다. 블렌드 내의 PEN의 T_g는 TLCP 함량이 증가함에 따라 119 ℃에서 116 ℃로 감소하였으나, T_m은 거의 변화를 보이지 않았고, TLCP가 매트릭스인 PEN에 대해 조혁제로 작용하였음을 알 수 있었다. 또한 냉각곡선에서 PEN의 결정화 온도는 TLCP 함량에 따라 증가함을 보여 주었다. 블렌드에서 액정상은 가공온도에서 거대 상분리 현상이나 열분해가 일어나지 않았으며, 제조된 복합재료의 매트릭스내의 액정상의 크기는 0.2㎛에서 0.3㎛로 잘 분산되었으며, 매트릭스와의 계면에서의 접착력도 우수하였음을 SEM으로부터 관찰하였다. 제조된 블렌드의 기계적 성질은 TLCP 함량이 많을수록 증가함을 확인할 수 있었다. A new thermotropic liquid crystalline polymer (TLCP) with ethoxy side group was synthesized for the preparation of in-situ composite, and the blends of TLCP with poly(ethylene 2,6-naphthalate) (PEN) were prepared by solution blending. TLCP, PEN and the blends (2, 5, 10 and 20 wt%) were characterized in terms of their thermal, mechanical and morphological properties. TLCP in the melt showed the nematic phase. The glass transition temperature (Tg) of PEN in the blends increased with increasing content of TLCP; TLCP acted as a nucleating agent for the matrix polymer. The crystallization temerature (Tc) of PEN in the blends increased with increasing content of TLCP. In the blends, liquid crystalline phase did not reveal any significant macrophase separation and thermal degradation at the processing temperature. From scanning electron micrographs of cryogenically fractured surfaces, the TLCP domains were found to be fine and uniformly dispersed having 0.2 to 0.3 ㎛ in size. Interfacial adhesion between TLCP and the matrix polymer was determined to be good. The modulus of TLCP/PEN blends were enhanced as TLCP`s content increased.
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전옥철,최재곤 조선대학교 생산기술연구소 1998 生産技術硏究 Vol.20 No.1
A new semirigid liquid crystalline polyester(LCP) was synthesized by polycondensation of 2,6-naphthalenedicarbonyl dichloride with the corresponding diol having a hexamethylene group. Blends composed of poly(ethylene 2,6-naphthalate, PEN) were prepared by the coprecipitation from a common solvent. The thermal. mechanical properties and morphology of blends were examined using differential scanning calorimeter(DSC), scanning electron microscope(SEM), and dynamic mechanical thermal analyzer(DMTA). The glass transition ternperature(T_(g)) and the cold crystallization ternperature(T_(c)) of the PEN in the blends decreased with increasing the content of LCP and the LCP acted as a nucleating agent for the matrix polymers. The LCP phases in the blends were found to be finely and uniformly dispersed by SEM micrographs. The modulus of LCP/PEN blends were enhanced on the LCP content increase.
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전옥철,김윤준,류범영,최재곤,조병욱,홍진후 조선대학교 생산기술연구소 1999 生産技術硏究 Vol.21 No.1
A series of wholly aromatic polyesters with side chains were synthesized by solution polycondensation from 2,5-dialkoxyterephthaloyl chlorides with the corresponding diol. The polymers showed the schlieren textures which is indicative of a nematic phase above their melting temperature. The inherent viscosities (η_(inh)) measured at 35℃ in phenol/p-chlorophenol/1,1,2,2-tetrachloroethane were 0.56-0.98 dℓ/g. The glass transition temperature (T_(g)) and melting temperature (T_(m)) decreased with increasing the length of the alkoxy side chain. Initial decomposition temperatures in TGA occurred at 338 ~ 363℃ in N₂ gas and thermal stability of polymers decreased with increasing the length of the side chain.
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조병욱,전옥철,김윤준,한철,최재곤 조선대학교 생산기술연구소 1999 生産技術硏究 Vol.21 No.2
A new thermotropic liquid crystalline copolyester(TLCP) was synthesized by condensation polymerization of 2,6-naphthalene dicarbonyl chloride with the corresponding diol having a tetramethylene and a hexarnethylene group. The blends of the TLCP with PEN were prepared by the coprecipitation from a common solvent. The TLCP and blends (2, 5, 10 and 20wt% TLCP) were characterized in terms of their thermal, mechanical properties and morphology. The TLCP in the melt state showed nematic mesophase identified by thread-like optical texture. The glass transition temperature (T_(g)) and cold crystallization temperature (T_(c)) of PEN in the blends decreased with increasing the content of TLCP and the TLCP acted as anucleating agent for the matrix polymer. Interfacial adhesion between the TLCP and PEN seemed to be poor. The modulus of TLCP/PEN blends was enhanced as the TLCP content increased.
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