Kee Yoon LEE - Academia.edu (original) (raw)
Papers by Kee Yoon LEE
Membrane Journal, 2021
Mesoporous polystyrene (PS) and polyethersulfone (PES) membranes have been fabricated by reverse-... more Mesoporous polystyrene (PS) and polyethersulfone (PES) membranes have been fabricated by reverse-thermally induced phase separation (RTIPS) process, using flash freezing. The mesoporous pores can be created by the nano-scaled phase separation induced by the formation and growth of solvent crystals in the dope solution in RTIPS process. RTIPS process has been characterized through analysis on the enthalpy change in the solvent of the dope solution, the morphology of the membrane fabricated with different polymer content, and the pore size distribution and its standard deviation of pore size of the membrane with polymer content via DSC, SEM, and BET, respectively. It is found that the kinetic aspect of the dope solution, i.e., the crystallization of solvent is a crucial factor to determine the structure of membrane fabricated in RTIPS rather than the thermodynamic aspect of the dope solution.
Polymer Korea, 2010
The mechanical properties of polypropylene (PP) composites, especially the effects of the filler ... more The mechanical properties of polypropylene (PP) composites, especially the effects of the filler shapes on the modulus were studied. The experimental results were investigated and compared with the theoretical approaches proposed by Lee and Paul and based on Eshelby's principle, which three dimensional ellipsoids were filled as filler and analyzed in terms of aspect ratio, ρ α =a 1 /a 3 and ρ β =a 1 /a 2. The shapes of fillers were observed by SEM and aspect ratios were statistically calculated. Young's moduli in the longitudinal and transverse directions for barium sulfate whose shape was sphere (ρ α =ρ β =1) had the same values, as predicted values. The modulus in the x 1 direction for a glass fibers increased as the filler content increased, while the modulus in the x 3 direction was increased relatively small. Furthermore, mica was also used to investigate the effects of the primary and secondary aspect ratios on the mechanical properties.
Polymer Korea, 2017
The effects of stoichiometric ratios of curing agent to prepolymer and temperature on the curing ... more The effects of stoichiometric ratios of curing agent to prepolymer and temperature on the curing reaction rates of polyurethane elastomer were investigated. The prepolymers were made from toluene diisocyanate (TDI) and polytetramethylene ether glycol (PTMEG) at 80 o C in nitrogen atmosphere for an hour. Then the prepolymers were mixed with the curing agent, 4,4'-methylene bis(2-chloroaniline) (MOCA) to produce polyurethane elastomer. The curing reactivities of polyurethane prepolymer with curing agent were measured by real time FTIR spectroscopy. The stoichiometric ratios were controlled from 0.85 to 1.05 at fixed curing temperatures from 80 to 120 o C. Conversions and reaction rates were increased, as the stoichiometric ratios increased. And they were increased, as the reaction temperatures increased. Kamal's equation was adopted for simulation as a kinetic model.
Polymer Korea, 2012
Solution type pressure sensitive acrylic adhesives were synthesized from 2-ethylhexyl acrylate (2... more Solution type pressure sensitive acrylic adhesives were synthesized from 2-ethylhexyl acrylate (2-EHA) as a base monomer and acrylic acid as a functional monomer. The surface energy and basic physical properties of synthesized PSA (pressure sensitive adhesives) were investigated as a function of contents of acrylic acid and crosslinking agent. The structures of adhesive were identified by FTIR. Viscosities and molecular weights of PSA were measured by a Brookfield viscometer and GPC, respectively. Consequently, molecular weight and viscosity increased as the contents of acrylic acid increased up to 6 wt% and then decreased at higher contents. Surface energy increased as the contents of acrylic acid increased owing to the increase of COOH groups, which yielded the enhancement of polarity of PSA. On the other hands, their peel strengths were inversely proportional to molecular weight and showed tendencies of decreasing as the contents of acrylic acid and crosslinking agent increased.
Polymer Korea, 2015
초록: 본 연구에서는 polyester계 polyol과 polymeric-methylene diphenyl diisocyanate(polymeric-MDI)를 사용하여 발포체... more 초록: 본 연구에서는 polyester계 polyol과 polymeric-methylene diphenyl diisocyanate(polymeric-MDI)를 사용하여 발포체를 형성할 때 아민계 젤화 촉매인 dimethylcyclohexyl amine(DMCHA)과 칼륨계 젤화 촉매인 potassium octoate(PO)가 발포체의 기계적 강도와 발포 셀의 분포에 미치는 영향에 대해 연구하였다. 첨가제로는 pentamethyl diethylene triamine(PMDETA) 촉매, 물, 발포제, 정포제를 사용하였다. 발포방식은 free rising test와 mold 공법을 사 용하였다. Universal testing machine(UTM)을 통해 굴곡강도를 측정하였다. 굴곡강도는 free rising test의 경우 DMCHA 촉매의 함량에 따라 약 0.20에서 약 0.12 MPa로 감소하였으나 mold 공법의 경우 약 1.10에서 약 1.35 MPa로 증가하여 반대의 경향을 보였다. PO 촉매의 함량에 따른 영향도 DMCHA 촉매와 유사하였다. 또한 scanning electron microscope(SEM)으로 젤화 촉매의 함량에 따라 cell population density(CPD)가 증가하는 것을 확 인하였고, 발포 셀의 크기 분포가 좁아지는 것을 확인하였다.
Polymer Korea, 2014
Polycarbonate (PC) and acrylonitrile-butadiene-styrene (ABS) blends were prepared using a high sh... more Polycarbonate (PC) and acrylonitrile-butadiene-styrene (ABS) blends were prepared using a high shear extruder to investigate their thermal decomposition and mechanical properties with shear rate and shear time. In this experiment, high shear rate, from 1000 to 3000 rpm, in blending process was applied for 10 to 40 sec, respectively. At high shear rate over than 2000 rpm, the initial decomposition temperature was dropped significantly compared to a compounded sample because of thermal decomposition of the blend by high shear. Consequently, high shear processing gave an important effect on the mechanical and thermal properties of the PC/ABS blend. In particular, elongation of the blend decreased significantly with shear rate.
Korean Chemical Engineering Research, 2014
The PC/ABS blends were manufactured with high shear rate processing. Changes of the blend morphol... more The PC/ABS blends were manufactured with high shear rate processing. Changes of the blend morphology were analyzed according to the screw speed and processing time. To find optimal conditions of the high shear rate processing of the PC/ABS blend, blend morphology and size of the dispersed phase, ABS, were observed with a SEM. Also, tensile properties of the PC/ABS blends were measured to investigate the effect of the high shear rate process with the screw speed of 500 rpm to 3000 rpm for processing times of 10s to 40s. Especially, to observe the dispersed phase of the PC/ABS blend clearly, fracture surfaces of the PC/ABS blend were etched with chromic acid solution. As screw
Polymer Korea, 2012
This paper studied the effects of the content and the orientation of the disk shape fillers on th... more This paper studied the effects of the content and the orientation of the disk shape fillers on the modulus of PP composites. The experimental results were compared with the theoretical calculations which included the three dimensional ellipsoids and analyzed by two aspect ratios, ρ α =a 1 /a 3 and ρ β =a 1 /a 2 proposed by Lee and his researchers. Mica and talc were used as disk shape fillers in the composites. The shapes of mica and talc were observed by SEM and aspect ratios were statistically calculated. For the case of mica, the average aspect ratios were ρ α =13.5 and ρ β =1.8, and for the case of talc, they were ρ α =3.8 and ρ β =1.4. Also, the effects of two aspect ratios and the content of filler on the mechanical properties were studied: For 30 wt% of mica, E 11 increased up to about 2.7 times, and for the other case of talc, E 11 increased up to about 2.3 times, respectively.
Polymer Korea, 2012
초록: 두 가지의 종횡비(ρ α = a 1 /a 3 and ρ β = a 1 /a 2)에 의해 특징지어진 3차원 타원체(a 1 > a 2 > a 3)를 사용하여
Polymer Korea, 2013
The curing behaviors of diglycidyl ether of bisphenol A (DGEBA) with mercaptan hardener were stud... more The curing behaviors of diglycidyl ether of bisphenol A (DGEBA) with mercaptan hardener were studied by the comparison with amine-adduct type hardener. Curing behaviors were evaluated by DSC at dynamic and isothermal conditions. In the DSC, the dynamic experiments were based on the method of Kissinger's equation, and the isothermal experiments were fitted to the Kamal's kinetic model. Activation energy of epoxy/amine-adduct type hardener was ca. 40 kcal/mol. As the functional group of mercaptan hardener,-SH increased, on epoxy/mercaptan hardeners, the activation energies decreased from 28 to 19 kcal/mol. Epoxy/amine-adduct type hardener was initiated at 90 o C or higher. However, epoxy/mercaptan hardeners reduced the initiation temperatures below 80 o C and shortened the durations of curing reaction within 10 min. We found out that the reaction kinetics of epoxy with mercaptan hardener followed the autocatalytic reaction models, and the maximum reaction rates were shown at the conversions of 20~40%.
Korean Chemical Engineering Research, 2014
Polycarbonate/Acrylonitrile-Butadiene-Styrene(PC/ABS) 블렌드의 분해효과를 조사하기 위해 고전단 압출 성형기의 스크류 회전속도와 전단... more Polycarbonate/Acrylonitrile-Butadiene-Styrene(PC/ABS) 블렌드의 분해효과를 조사하기 위해 고전단 압출 성형기의 스크류 회전속도와 전단시간의 함수로 PC/ABS의 물성변화에 영향을 미치는 산화방지제의 효과를 연구하였다. 인산계 산화방지제로 Tris-(2,4-di-tert-butyl-phenyl phosphate) (이후 A1로 명명) and Bis(2,4-dicumylphenyl) pentaerythritol diphosphite(이후 A3로 명명)가 사용되었고, 페놀계 산화방지제는 Octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate(이후 A2로 명명)가 사용되었다. 열적 물성은 TGA를 통해 측정되었고 고속 전단 가공 후 크게 감소하였다.
The effects of high shear rate processing on the thermal properties of PC/ABS blends were studied... more The effects of high shear rate processing on the thermal properties of PC/ABS blends were studied. It was executed by the high shear processing machine (NHSS2-28) at the varied conditions of screw speeds and loaded duration. After the samples were processed with NHSS2-28, the T g s were shifted from 143 to 133 o C, and the behavior of degradation determined by TGA showed two distinct steps before high shear rate processing, while it showed a straight line after the processing. In order to provide the reasons of the properties, it was showen by SEM and UTM that the droplet sizes morphologically decreased after the processing, and the elongations decreased slightly until 1000 rpm of screw speed and then sharply decreased, according to the conditions of high shear rate processing. Therefore, it can be confirmed that T g ,s of PC/ABS blends were considerably shifted under an appropriate high shear rate condition, and rapidly dropped, so that blends degraded above the condition, due to stress-induced degradation.
Membrane Journal, 2021
Mesoporous polystyrene (PS) and polyethersulfone (PES) membranes have been fabricated by reverse-... more Mesoporous polystyrene (PS) and polyethersulfone (PES) membranes have been fabricated by reverse-thermally induced phase separation (RTIPS) process, using flash freezing. The mesoporous pores can be created by the nano-scaled phase separation induced by the formation and growth of solvent crystals in the dope solution in RTIPS process. RTIPS process has been characterized through analysis on the enthalpy change in the solvent of the dope solution, the morphology of the membrane fabricated with different polymer content, and the pore size distribution and its standard deviation of pore size of the membrane with polymer content via DSC, SEM, and BET, respectively. It is found that the kinetic aspect of the dope solution, i.e., the crystallization of solvent is a crucial factor to determine the structure of membrane fabricated in RTIPS rather than the thermodynamic aspect of the dope solution.
Polymer Korea, 2010
The mechanical properties of polypropylene (PP) composites, especially the effects of the filler ... more The mechanical properties of polypropylene (PP) composites, especially the effects of the filler shapes on the modulus were studied. The experimental results were investigated and compared with the theoretical approaches proposed by Lee and Paul and based on Eshelby's principle, which three dimensional ellipsoids were filled as filler and analyzed in terms of aspect ratio, ρ α =a 1 /a 3 and ρ β =a 1 /a 2. The shapes of fillers were observed by SEM and aspect ratios were statistically calculated. Young's moduli in the longitudinal and transverse directions for barium sulfate whose shape was sphere (ρ α =ρ β =1) had the same values, as predicted values. The modulus in the x 1 direction for a glass fibers increased as the filler content increased, while the modulus in the x 3 direction was increased relatively small. Furthermore, mica was also used to investigate the effects of the primary and secondary aspect ratios on the mechanical properties.
Polymer Korea, 2017
The effects of stoichiometric ratios of curing agent to prepolymer and temperature on the curing ... more The effects of stoichiometric ratios of curing agent to prepolymer and temperature on the curing reaction rates of polyurethane elastomer were investigated. The prepolymers were made from toluene diisocyanate (TDI) and polytetramethylene ether glycol (PTMEG) at 80 o C in nitrogen atmosphere for an hour. Then the prepolymers were mixed with the curing agent, 4,4'-methylene bis(2-chloroaniline) (MOCA) to produce polyurethane elastomer. The curing reactivities of polyurethane prepolymer with curing agent were measured by real time FTIR spectroscopy. The stoichiometric ratios were controlled from 0.85 to 1.05 at fixed curing temperatures from 80 to 120 o C. Conversions and reaction rates were increased, as the stoichiometric ratios increased. And they were increased, as the reaction temperatures increased. Kamal's equation was adopted for simulation as a kinetic model.
Polymer Korea, 2012
Solution type pressure sensitive acrylic adhesives were synthesized from 2-ethylhexyl acrylate (2... more Solution type pressure sensitive acrylic adhesives were synthesized from 2-ethylhexyl acrylate (2-EHA) as a base monomer and acrylic acid as a functional monomer. The surface energy and basic physical properties of synthesized PSA (pressure sensitive adhesives) were investigated as a function of contents of acrylic acid and crosslinking agent. The structures of adhesive were identified by FTIR. Viscosities and molecular weights of PSA were measured by a Brookfield viscometer and GPC, respectively. Consequently, molecular weight and viscosity increased as the contents of acrylic acid increased up to 6 wt% and then decreased at higher contents. Surface energy increased as the contents of acrylic acid increased owing to the increase of COOH groups, which yielded the enhancement of polarity of PSA. On the other hands, their peel strengths were inversely proportional to molecular weight and showed tendencies of decreasing as the contents of acrylic acid and crosslinking agent increased.
Polymer Korea, 2015
초록: 본 연구에서는 polyester계 polyol과 polymeric-methylene diphenyl diisocyanate(polymeric-MDI)를 사용하여 발포체... more 초록: 본 연구에서는 polyester계 polyol과 polymeric-methylene diphenyl diisocyanate(polymeric-MDI)를 사용하여 발포체를 형성할 때 아민계 젤화 촉매인 dimethylcyclohexyl amine(DMCHA)과 칼륨계 젤화 촉매인 potassium octoate(PO)가 발포체의 기계적 강도와 발포 셀의 분포에 미치는 영향에 대해 연구하였다. 첨가제로는 pentamethyl diethylene triamine(PMDETA) 촉매, 물, 발포제, 정포제를 사용하였다. 발포방식은 free rising test와 mold 공법을 사 용하였다. Universal testing machine(UTM)을 통해 굴곡강도를 측정하였다. 굴곡강도는 free rising test의 경우 DMCHA 촉매의 함량에 따라 약 0.20에서 약 0.12 MPa로 감소하였으나 mold 공법의 경우 약 1.10에서 약 1.35 MPa로 증가하여 반대의 경향을 보였다. PO 촉매의 함량에 따른 영향도 DMCHA 촉매와 유사하였다. 또한 scanning electron microscope(SEM)으로 젤화 촉매의 함량에 따라 cell population density(CPD)가 증가하는 것을 확 인하였고, 발포 셀의 크기 분포가 좁아지는 것을 확인하였다.
Polymer Korea, 2014
Polycarbonate (PC) and acrylonitrile-butadiene-styrene (ABS) blends were prepared using a high sh... more Polycarbonate (PC) and acrylonitrile-butadiene-styrene (ABS) blends were prepared using a high shear extruder to investigate their thermal decomposition and mechanical properties with shear rate and shear time. In this experiment, high shear rate, from 1000 to 3000 rpm, in blending process was applied for 10 to 40 sec, respectively. At high shear rate over than 2000 rpm, the initial decomposition temperature was dropped significantly compared to a compounded sample because of thermal decomposition of the blend by high shear. Consequently, high shear processing gave an important effect on the mechanical and thermal properties of the PC/ABS blend. In particular, elongation of the blend decreased significantly with shear rate.
Korean Chemical Engineering Research, 2014
The PC/ABS blends were manufactured with high shear rate processing. Changes of the blend morphol... more The PC/ABS blends were manufactured with high shear rate processing. Changes of the blend morphology were analyzed according to the screw speed and processing time. To find optimal conditions of the high shear rate processing of the PC/ABS blend, blend morphology and size of the dispersed phase, ABS, were observed with a SEM. Also, tensile properties of the PC/ABS blends were measured to investigate the effect of the high shear rate process with the screw speed of 500 rpm to 3000 rpm for processing times of 10s to 40s. Especially, to observe the dispersed phase of the PC/ABS blend clearly, fracture surfaces of the PC/ABS blend were etched with chromic acid solution. As screw
Polymer Korea, 2012
This paper studied the effects of the content and the orientation of the disk shape fillers on th... more This paper studied the effects of the content and the orientation of the disk shape fillers on the modulus of PP composites. The experimental results were compared with the theoretical calculations which included the three dimensional ellipsoids and analyzed by two aspect ratios, ρ α =a 1 /a 3 and ρ β =a 1 /a 2 proposed by Lee and his researchers. Mica and talc were used as disk shape fillers in the composites. The shapes of mica and talc were observed by SEM and aspect ratios were statistically calculated. For the case of mica, the average aspect ratios were ρ α =13.5 and ρ β =1.8, and for the case of talc, they were ρ α =3.8 and ρ β =1.4. Also, the effects of two aspect ratios and the content of filler on the mechanical properties were studied: For 30 wt% of mica, E 11 increased up to about 2.7 times, and for the other case of talc, E 11 increased up to about 2.3 times, respectively.
Polymer Korea, 2012
초록: 두 가지의 종횡비(ρ α = a 1 /a 3 and ρ β = a 1 /a 2)에 의해 특징지어진 3차원 타원체(a 1 > a 2 > a 3)를 사용하여
Polymer Korea, 2013
The curing behaviors of diglycidyl ether of bisphenol A (DGEBA) with mercaptan hardener were stud... more The curing behaviors of diglycidyl ether of bisphenol A (DGEBA) with mercaptan hardener were studied by the comparison with amine-adduct type hardener. Curing behaviors were evaluated by DSC at dynamic and isothermal conditions. In the DSC, the dynamic experiments were based on the method of Kissinger's equation, and the isothermal experiments were fitted to the Kamal's kinetic model. Activation energy of epoxy/amine-adduct type hardener was ca. 40 kcal/mol. As the functional group of mercaptan hardener,-SH increased, on epoxy/mercaptan hardeners, the activation energies decreased from 28 to 19 kcal/mol. Epoxy/amine-adduct type hardener was initiated at 90 o C or higher. However, epoxy/mercaptan hardeners reduced the initiation temperatures below 80 o C and shortened the durations of curing reaction within 10 min. We found out that the reaction kinetics of epoxy with mercaptan hardener followed the autocatalytic reaction models, and the maximum reaction rates were shown at the conversions of 20~40%.
Korean Chemical Engineering Research, 2014
Polycarbonate/Acrylonitrile-Butadiene-Styrene(PC/ABS) 블렌드의 분해효과를 조사하기 위해 고전단 압출 성형기의 스크류 회전속도와 전단... more Polycarbonate/Acrylonitrile-Butadiene-Styrene(PC/ABS) 블렌드의 분해효과를 조사하기 위해 고전단 압출 성형기의 스크류 회전속도와 전단시간의 함수로 PC/ABS의 물성변화에 영향을 미치는 산화방지제의 효과를 연구하였다. 인산계 산화방지제로 Tris-(2,4-di-tert-butyl-phenyl phosphate) (이후 A1로 명명) and Bis(2,4-dicumylphenyl) pentaerythritol diphosphite(이후 A3로 명명)가 사용되었고, 페놀계 산화방지제는 Octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate(이후 A2로 명명)가 사용되었다. 열적 물성은 TGA를 통해 측정되었고 고속 전단 가공 후 크게 감소하였다.
The effects of high shear rate processing on the thermal properties of PC/ABS blends were studied... more The effects of high shear rate processing on the thermal properties of PC/ABS blends were studied. It was executed by the high shear processing machine (NHSS2-28) at the varied conditions of screw speeds and loaded duration. After the samples were processed with NHSS2-28, the T g s were shifted from 143 to 133 o C, and the behavior of degradation determined by TGA showed two distinct steps before high shear rate processing, while it showed a straight line after the processing. In order to provide the reasons of the properties, it was showen by SEM and UTM that the droplet sizes morphologically decreased after the processing, and the elongations decreased slightly until 1000 rpm of screw speed and then sharply decreased, according to the conditions of high shear rate processing. Therefore, it can be confirmed that T g ,s of PC/ABS blends were considerably shifted under an appropriate high shear rate condition, and rapidly dropped, so that blends degraded above the condition, due to stress-induced degradation.