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고속전단에 의한 폴리카보네이트/ABS 블렌드의 열분해 및 기계적 특성 연구
유재정(Jae Jung Yoo),용다경(Da Kyoung Yong),이한기(Han Ki Lee),김대식(Dae Sik Kim),이형일(Hyung Il Lee),김선홍(Sun Hong Kim),이기윤(Kee Yoon Lee),이승구(Seung Goo Lee) 한국고분자학회 2014 폴리머 Vol.38 No.4
Polycarbonate (PC)/acrylonitrile-butadiene-styrene (ABS) 블렌드를 고속전단압축성형기로 1000rpm 이상의 소크류 속도로 압출하여 전단속도와 전단시간에 따른 PC/ABS 블렌드의 열분해와 기계적 특성을 조사하였다. 고속전단조건으로 스크류 회전속도를 1000에서 3000rpm 범위에서 조절하였고, 전단부하시간은 10에서 40초로 변화를 주었다. 그 결과, 2000 rpm 이상의 고속전단을 통해 얻어진 시편의 경우, 고분자의 열분해의 발생으로 열분해 시작 온도가 낮아졌다. 스크류 회전속도와 전단부하시간에 따라 열분해에 의하여 시편의 인장강도와 신율이 낮아지는 결과를 얻었다. 이러한 PC/ABS 블렌드의 고속전단 조건에 따라 기계적 특성이 크게 변화하였으며 특히, 신율이 고속전단에 크게 영향을 받았다. Polycarbonate (PC) and acrylonitrile-butadiene-styrene (ABS) blends were prepared using a high shear extruder to investigate 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 10to 40 sec, respectively. At high shear rate over than 2000 rpm, the initial decomposition temperature was dropped significantly compared to a com-pounded 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.
지르코니아 나노섬유를 함유한 PAN계 탄소섬유의 제조 및 특성 분석
양지우,유재정,장혜진,용다경,원종성,이승구,Yang, Jee-Woo,Yoo, Jae Jung,Jang, Hae Jin,Yong, Da Kyung,Won, Jong Sung,Lee, Seung Goo 한국섬유공학회 2012 한국섬유공학회지 Vol.49 No.5
There has been steady needs for the PAN based carbon fibers, which have high thermal insulation properties and high mechanical properties. Thus, in this study, low thermal conductive PAN carbon fibers were prepared by using zirconia nanofibers, which were prepared from the electrospinning and sol-gel synthesis of zirconium oxide. Wet spun PAN fibers containing the zirconia nanofibers were stabilized and carbonized in order to prepare the composite carbon fibers. Based on the characterization results using scanning electron microscope (SEM), FT-IR, thermo-gravimetric analysis (TGA), and thermal conductivity measurement, the optimal conditions of composite carbon fibers were established. In addition, the thermal conductivity of prepared composite carbon fibers was reduced considerably by the effects of zirconia nanofiber inclusions.
저융점 폴리에스터와 텐셀을 이용한 싸이로필사의 제조와 물성 분석
이선영,유재정,홍윤광,이시우,이승구,Lee, Sun-Young,Yoo, Jae-Jung,Hong, Yun-Kwang,Lee, Si-Woo,Lee, Seung-Goo 한국섬유공학회 2012 한국섬유공학회지 Vol.49 No.2
The purposes of this study were to manufacture sirofil yarn using tencel roving and low melting polyester filaments and to analyze the physical properties of sirofil yarns with yarn count, in order to develop composite yarn for high glossy and luxury textile fabrics. The surface morphology of sirofil yarn was observed with the SEM. Tensile and bending properties of sirofil yarn were examined with the yarn count. The tensile fracture of sirofil yarn was shown with a two-step process. Firstly, tencel yarn having low elongation was broken and then the low melting polyester filaments were fractured with very high elongation. Bending properties of sirofil yarn were measured with the KES-FB. The bending rigidity of sirofil yarn was between that of tencel spun yarn and that of low melting polyester. Also, the surface property of sirofil yarn was evaluated in terms of the hairiness coefficient. It was shown that stress, strain, bending rigidity, bending hysteresis and surface hairiness coefficient of sirofil yarn decreased as yarn count increased.
김희영 ( Hee-young Kim ),정희진 ( Hee-jin Jung ),유재정 ( Jae-jung Yoo ),임태효 ( Tae-hyo Lim ),임영경 ( Young-kyong Lim ),오정은 ( Jeong-eun Oh ) 한국환경분석학회 2016 환경분석과 독성보건 Vol.19 No.1
In this study, eight pesticides belonging to the groups of carbamates, phenoxy-acids, heterocyclics were analyzed to identify their concentrations and distribution patterns at various sampling locations (20 sites) in the Nakdong River basin during various sampling periods (May, July, September, and November 2012). Among the eight pesticides, carbofuran showed the highest mean concentration (0.0335 μg/L), followed by methomyl (0.0138 μg/L) and quinoline (0.0070 μg/L), while aldicarb and molinate were observed below the method detection limit (MDL). Quinoline was the most frequently detected pesticide with a detection frequency of 85- 100% in all the sampling periods. The concentration levels and the detection frequencies of the pesticides seemed to be related with the pesticides’ shipment/production. Among the four sampling periods, September showed the highest mean and median concentrations, although the differences were not statistically significant. The concentration levels were higher in the midstream area than the up and downstream areas of the Nakdong River, because a number of potential contamination pathways such as wastewater treatment plants, industrial facilities and agricultural fields were located in this zone. All these non-cancer-causing pesticides, except quinolone, showed no risk value (risk assessment value < 1). This study could be used as basic data for risk assessment and analysis procedures for quality assurance and quality control of pesticides in Korea.
고속 전단 가공에서 페놀계와 인산계 산화방지제에 의한 PC/ABS 블렌드의 물성 변화 연구
이한기 ( Han Ki Lee ),김선홍 ( Seon Hong Kim ),이형일 ( Hyung Il Lee ),유재정 ( Jae Jung Yoo ),용다경 ( Da Kyoung Yong ),최석진 ( Seok Jin Choi ),이승구 ( Seung Goo Lee ),이기윤 ( Kee Yoon Lee ) 한국화학공학회 2014 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.52 No.2
Polycarbonate/Acrylonitrile-Butadiene-Styrene(PC/ABS) 블렌드의 분해효과를 조사하기 위해 고전단 압출 성형기의스크류 회전속도와 전단시간의 함수로 PC/ABS의 물성변화에 영향을 미치는 산화방지제의 효과를 연구하였다. 인산계산화방지제로 Tris-(2,4-di-tert-butyl-phenyl phosphate) (이후 A1로 명명) and Bis(2,4-dicumylphenyl) pentaerythritoldiphosphite(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. 산화방지제 A3가 포함된 PC/ABS 블렌드는 다른 산화방지제에 비해 스트레스로 유발된 degradation과, 열적 degradation이지연되었다. 고속 전단 가공 후 UTM을 사용한 기계적 물성 또한 산화방지제 종류에 따라 각각 감소하였고, 특히, 신율의 경우 크게 감소하는 거동이 나타난 것에 비해 인장강도의 변화는 매우 적었다. 스크류 회전속도 1000 rpm, 전단부하 시간 20초 조건에서의 신율로 예를 들면, 고속 전단 가공하기 전 신율인 148%에서 A1은 91.6%, A2는 63%, A3은 131%로 감소하였다. 형태학적 물성을 알기 위해 SEM을 사용하여 PC/ABS의 분산상을 조사하였고, 스크류 회전속도와 하중이 작용한 기간이 증가함에 따라 그 크기 분포가 감소하였다. 따라서, 세 종류 산화방지제 모두 고속 전단 가공에서 스트레스로 유발되는 PC/ABS 블렌드의 degradation을 억제하고, 그 효과는 A3가 가장 뛰어난 것을 확인하였다. The effects of antioxidants on the properties of Polycarbonate/Acrylonitrile-Butadiene-Styrene(PC/ABS)blends were studied for the functions of the screw speed and loaded duration of high shear rate processing in order to investigate the degradation for PC/ABS blends. Tris-(2,4-di-tert-butyl-phenyl phosphate) (A1) and Bis(2,4-dicumylphenyl) pentaerythritol diphosphite (A3) as phosphite antioxidants and Octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate(A2) as a phenolic antioxidant are used. The thermal properties were detected by TGA and severely decreased, after the processing. The stress-induced and thermal degradation for PC/ABS blends with the antioxidant A3 was retarded better than the others. By using UTM, the mechanical properties also showed individually decreased according to the antioxidants, after the processing, especially, the elongations showed considerable decline behaviors, while the tensile strengths of PC/ABS blends changed very little. For example, in the operating conditions of 1000rpm of screw speed and 20 seconds of loaded period, the elongations decreased from 148% before the processing, to 91.6% with the A1, to63% with the A2 and to 131% with the A3 after the processing, respectively. In order to get the morphological properties, the size distributions of the dispersed phases for PC/ABS were investigated by SEM analysis and tended to decrease, as the screw speed and loaded period of the processing increased. Therefore, we confirmed that the antioxidantA3 was the best of all of three to inhibit the stress-induced degradation of PC/ABS blends during the high shear rate processing.