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직연신 방사과정에서의 폴리프로필렌 필라멘트의 물리적 특성에 관한 연구(I) -분자량 및 권취속도에 따른 구조해석-
한승산,신현세,이태균 한국섬유공학회 2002 한국섬유공학회지 Vol.39 No.1
Structural changes of polypropylene fibers during a direct draw melt spinning process were analyzed by comparing fibers which have gone through the direct draw melt spinning process with those for which the drawing step was omitted. The relative contribution of the drawing step was evaluated so that the information on the stages of development of the structure can be applied as a basis for future research on functional or high performance fibers. Four different molecular weights and take-up speeds were applied to study the effect of these variables on the development of the structure. When the effect of differences in molecular weight was compared with that of differences in take-up speed on the physical properties, the variation width of the properties for the former appeared about 2~4.5 times higher than for the latter. When the properties of the drawn filaments were taken as reference and the degree of structure formation in the undrawn filaments was described by the percentage thereof, 85 and 95% of crystallinity and crystalline orientation had already been developed prior to the drawing step, respectively. On the other hand, the overall orientation was found to be more dependent on the drawing process, with about 64-73% of the orientation being developed in the drawing step and 26.8-36.1% being developed prior to the drawing step. The amorphous orientation of the undrawn fibers exhibited a negative value suggesting that the rotation of lamella to the final structure occurs in the drawing step.
고분자로 표면 코팅된 BaTiO<sub>3</sub>와 이를 이용한 폴리이미드 나노복합필름의 제조 및 특성
한승산,한지연,최길영,임승순,김용석,Han, Seung San,Han, Ji Yun,Choi, Kil-Yeong,Im, Seung Soon,Kim, Yong Seok 한국공업화학회 2006 공업화학 Vol.17 No.5
본 연구는 커패시터(capacitor) 등의 유전재료로서 응용이 가능한 고분자로 코팅된 무기입자 및 이를 이용하여 제조된 유전율이 높은 폴리이미드(polyimide; PI) 나노복합재에 관한 것이다. 무기입자로는 높은 유전상수를 가지는 barium titanate(BT)를 선정하였고, 이를 유기 고분자인 나일론 6으로 표면 코팅하여 매트릭스 고분자인 폴리이미드와의 친화력을 향상시켰다. FT-IR과 TEM을 통하여 5 nm 두께의 고분자 셀(shell)이 형성된 친유기화된 무기입자(BTN)를 확인하였으며, 나일론 6이 코팅된 BT의 내경과 외경의 비, 그리고 $\alpha$와의 관계를 나타낸 모식도를 통해 고분자 코팅 두께를 조절할 수 있음을 제안하였다. 제조된 BTN과의 복합화를 통하여 폴리아믹산 나노복합용액을 제조하였으며, 이를 탈수 고리화하여 열적 및 전기적 특성이 우수한 폴리이미드 나노복합필름을 제조하였다. SEM을 통하여 BTN이 매트릭스 고분자 내에 균일 분산상을 형성함을 확인하였으며, TGA와 전기적 측정을 통하여 BTN의 함량에 따른 폴리이미드 나노복합필름의 열안정성 지수, 적분 열분해 온도 및 유전율의 변화를 각각 조사하였다. We have prepared organophilic inorganic particles and polyimide (PI) nanocomposite having excellent thermal stability and high dielectric constant that can be used for electronic application such as capacitor. We have chosen barium titanate (BT), a high dielectric constantmaterial and its surface was coated with nylon 6 to improve the affinity with PI. The FT-IR and TEM studies showed that the organophilic inorganic particle (BTN) has a polymer shell with thickness of 5 nm. We have suggested that it is possible to control the thickness of coating surface and also indicated the relationship between the ratio of inside and outside radius of BTN and the weight fraction of BT. The PI nanocomposite films based on poly(amic acid) and BTN were prepared by cyclodehydration reaction. The homogeneous dispersion of BTN in PI matrix was identified by using SEM. We have investigated the effect of BTN content on the coefficient of thermal stability, integral procedural decomposition temperature (IPDT), and dielectric constant of PI nanocomposite films.