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Experimental and factorial study on gas separation properties of PLA-based green composite membranes
Yılmaz Sedef Yüksel,Özen Hülya Aykaç,Geyikçi Feza 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.12
Polylactide acid (PLA) is a biocompatible sustainable material with notable characteristics due to its good mechanical properties and low environmental impact. The present study investigated the effects of PLA-based green membranes on gas separation and identified the best factor condition for the membrane. Prepared membranes were tested to determine oxygen (O2) and carbon dioxide (CO2) gas permeability properties. Oxygen gas permeability of the PLA/PEG/HA membrane obtained by drying for two days was increased from 100 kPa to 400 kPa; the permeability value of this membrane increased by 15%. On the other hand, the oxygen permeability value of the membrane prepared by dry for three days under the same pressure conditions and ambient temperature increased by 5%. This result indicates that the permeabilities of prepared membranes for O2 gas increase with increasing feed pressures. On the other hand, it was observed that the CO2 permeability decreased by 38.83% with the increase in pressure and drying time due to the plasticizing and swelling effect of carbon dioxide on the membrane. A factorial design was also constructed from experimental data and applied to determine the interactions of experimental parameters. All of the parameter interactions were of statistical significance for permeability. It is further argued that molecular weight has a significant positive effect on permeability, while dry time and pressure have just a slight negative effect. This study could contribute to further studies by reducing the number of tests necessary to understand the characteristics and gas separation performance of green materials.
Effects of Dynamic Soil Behaviour on Wave-Induced Seabed Response
D.H. CHA,D.S. JENG,M.S. RAHMAN,H. SEKIGUCHI,K. ZEN,H. YAMAZAKI 한국해양공학회 2002 韓國海洋工學會誌 Vol.16 No.5
In this paper, an analytical solution for the wave-induced seabed response in a porous seabed is derived. Unlike previous investigations with quasi-static soil behaviour, dynamic soil behaviour is considered in the new solution. The basic one-dimensional framework proposed by Zienkiewicz et al (1980) is extended to two-dimensional cases. Based on the analytical solution derived, the effects of dynamic soil behaviour on the wave-induced seabed response are examined. The boundary of quasi-static soil behaviour and dynamic soil behaviour is clarified, and formulated for engineering practice.
Effects of Dynamic Soil Behaviour on Wave-Induced Seabed Response
Cha, D.H.,Jeng, D.S.,Rahman, M.S.,Sekiguchi, H.,Zen, K.,Yamazaki, H. Korean Society of Ocean Engineers 2002 International journal of ocean engineering and tec Vol.5 No.1
In this paper, an analytical solution for the wave-induced seabed response in a porous seabed is derived. Unlike previous investigations with quasi-static soil behaviour, dynamic soil behaviour is considered in the new solution. The basic one-dimensional framework proposed by Zienkiewicz et al (1980) is extended to two-dimensional cases. Based on the analytical solution derived, the effects of dynamic soil behaviour on the wave-induced seabed response are examined. The boundary of quasi-static soil behaviour and dynamic soil behaviour is clarified, and formulated for engineering practice.
Morphological similarity of a tri-block copolymer processed at ambient and elevated temperatures
Sebnem Inceoglu,Taner Aytun,Yusuf Z. Mencelo lu,lhan Özen,Metin H. Acar 한국유변학회 2012 Korea-Australia rheology journal Vol.24 No.4
We investigated the effect of temperature on the morphology of a tri-block copolymer (BCP) processed in a capillary rheometer. The material used was a polystyrene-b-poly(2-ethylhexyl acrylate)-b-polystyrene (PS-b-PEHA-b-PS) tri-block copolymer, which was synthesized by ATRP with a molecular weight of 38.5 K consisting of 49 molar % PEHA. According to the rheological data obtained with dynamic viscoelastic oscillatory measurements, order-disorder temperature (ODT) of the BCP was measured at around 110oC. Considering this observation, the samples were studied under different temperatures and pressures (from 110°C to 28°C and from 48 to 75 bar) in capillary rheometer. All processed materials were characterized by using differential scanning calorimetry (DSC) and atomic force microscopy (AFM). It was found that all samples processed by aid of either temperature or pressure showed similar mixed morphologies (a mixture of the ordered and disordered structures i.e., the reduction of microphase separation due to processing).
Mahmoud Bakr,R. Kinjo,Y. W. Choi,M. Omer,K. Yoshida,S. Ueda,M. Takasaki,K. Ishida,N. Kimura,H. Zen,T. Sonobe,T. Kii,K. Masuda,H. Ohgaki 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.51
The heating property of LaB_6 and CeB_6 cathodes is investigated against the Back Bombardment (BB) effect in thermionic RF guns using numerical calculation of the stopping range and deposited heat power inside the cathode materials. Then the change in a cathode temperature and corresponding change of current density during 5.5 μs pulse duration are determined by solving two differential equations. The simulation results show that, the change of current density during the macropulse for LaB_6 two times higher than for CeB_6, hence, the effect of the BB electrons in CeB_6 is less than for LaB_6.