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최은엽,김무현,이승연,김창근,신정채 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.1
Life of thermoplastic polyurethane (TPU) hose used in underwater acoustic sensor was predicted by using accelerated life test (ALT). The ALT was conducted by aging the TPU hose in four different heating conditions at 40, 70, 85, 100, 110 and 125 °C. After aging, the mechanical properties of TPU hose measured for given periods. Changes in the mechanical properties were expressed as master curves by regression method and then the failure times of TPU hose was obtained from the master curves. To interpret the ALT data of TPU hose, mathematical relations including life distribution and acceleration models were used and their parameters were estimated by using the maximum likelihood estimation (MLE) method. The MLE result indicated that Arrhenius model and Weibull distribution provides the best fit for the ALT data. From the Arrhenius-Weibull model, the failure time of half of TPU hose for tensile strength and tear resistance were estimated to be 90.0 and 16.4 years, respectively.
최은엽,이승연,김창근 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.100 No.-
To produce nylon 6,6 (N66)-based composites with carbonfiber (CF) having extremely high mechanicalstrength, CF covalently bonded with carbon nanotube (CNT), CF–c–CNT, wasfirst produced by reactingfunctionalized CF and CNT and then a composite of N66 and CF–c–CNT was produced by melt extrusion. Two types of CF–c–CNT were prepared: CF and CNT functionalized with acyl chloride (COCl) and aminegroup (NH2), respectively (COCl–CF–c–CNT–NH2), and CF and CNT functionalized with NH2 and COCl,respectively (NH2–CF–c–CNT–COCl). N66 bonding to CF–c–CNT occurred during extrusion by thereaction of COCl with amine groups in N66. Thus, N66 bonded to CF (N66–CF–c–CNT) and N66 bonded toCNT (CF–c–CNT–N66) were formed. The N66/CF–c–CNT–N66 composite exhibited the highest interfacialadhesion, the bestfiller dispersion, and the greatest amount of N66 bonding tofiller among thecomposites tested. As a result, the N66/CF–c–CNT–N66 composite had the highest tensile strength andfatigue life among the composites. The tensile strength and fatigue life of the N66/CF–c–CNT–N66composite were 20% higher andfive times longer than those of the N66/CF composite, respectively.
최은엽,신정채,이재영,김무현,김창근 한국고분자학회 2020 Macromolecular Research Vol.28 No.5
The lifetime of thermoplastic polyurethane (TPU) encapsulants used in underwater acoustic sensor (UAS) was predicted using accelerated life testing (ALT). The TPU specimens for tensile and tear strength tests were aged at six different temperatures, and the strengths of the aged specimens were then measured. The measured tensile and tear strengths as a function of aging temperature were used as ALT data for the analysis of the TPU encapsulant lifetime using ReliaSoft’s ALTA software. For the analysis of ALT data, the acceleration models and the life distribution models in the ALTA software were combined. The maximum likelihood estimation (MLE) method was used to find the most reliable acceleration-life distribution model when interpreting ALT data for tensile and tear strengths. It reveals that the Arrhenius-Weibull distribution model best fits the ALT data of the TPU encapsulant. The lifetime of the TPU encapsulant for tensile and tear strength was estimated using the Arrhenius-Weibull distribution model. The estimated results exhibited that the lifetime for tear stress was much shorter than that for tensile stress at 25 °C. Tensile and tear stresses are applied simultaneously to the TPU encapsulant during UAS operation. Thus, its replacement time should be determined by its tear strength lifetime.
최은엽,김성원,김창근 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.1
Multi-walled carbon nanotubes (MWCNTs), expected as effective fillers of polymer composites, were chemically treated with hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) to improve their morphological disabilities. Morphology of MWCNTs were changed by reacting with H<sub>2</sub>O<sub>2</sub>, and waviness of MWCNTs were also decreased with time and temperature dependently. It has been shown that H<sub>2</sub>O<sub>2</sub> is used for introducing hydroxyl groups on the surface of MWCNTs, and it mainly attacks defect sites of MWCNTs such as non-aromatic structures. As a result, waviness of MWCNTs were changed because defect sites affects curliness of MWCNTs. Polymer composites such as PC, PA66, PBT and PE were fabricated with chemically treated MWCNTs and tensile test were conducted to confirm the improvement of morphological properties affected on the mechanical properties of CNT-filled composites.
아미네이트 폴리에테르설폰 표면에 그래핀 옥사이드가 그래프트된 분리막의 한외여과 특성
최은엽(Eun Yeop Choi),이소민(Somin Lee),김창근(Chang Keun Kim) 한국고분자학회 2022 폴리머 Vol.46 No.6
한외여과막 재료로서 폴리에테르설폰(PES)의 단점인 소수성과 낮은 항균성을 극복하기 위해, 아민화된 PES(aPES) 막 표면에 그래핀 옥사이드(GO)가 그래프트된 한외여과막을(aPES-GO) 제조하였다. aPES 한외여과막의 수투과도는 분리막 내의 aPES 함량이 증가함에 따라 증가하였고, 분리막 내의 aPES 함량이 20 wt% 이하일 경우 분리막의 용질 제거율은 PES 분리막과 거의 동일하였다. aPES-GO 한외여과막의 수투과도는 용질 제거율의 감소 없이 그래프트된 GO의 양이 증가함에 따라 더욱 증가하였다. 또한, aPES-GO 멤브레인은 GO에 기인한 항균성과 aPES 및 GO에 의해 부여된 친수성으로 인해 우수한 내오염 특성을 나타냈다. To overcome the disadvantages of polyethersulfone (PES) as an ultrafiltration membrane material including hydrophobicity and low antibacterial properties, an aminated PES (aPES) membrane grafted with graphene oxide (GO) onto the membrane surface (aPES-GO) were prepared. The water flux of the aPES ultrafiltration membrane increased as the aPES content in the membrane increased, and when the aPES content in the membrane was 20 wt% or less, the solute rejection of the membrane was almost the same as that of PES. The water flux of the aPES-GO membrane increased further as the amount of grafted GO increased without a reduction in solute rejection. In addition, the aPES-GO membrane exhibited excellent antifouling characteristics due to the antibacterial properties provided by GO and the hydrophilicity originated from aPES and GO.