• Title/Summary/Keyword: 가소성

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Functional Properties of Cellulose-Based Films (셀룰로오스 포장지의 기능성)

  • Kim, Young-Ho;Park, Hyun-Jin;Kim, Dong-Man;Kim, Kil-Hwan
    • Korean Journal of Food Science and Technology
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    • v.26 no.2
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    • pp.133-137
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    • 1994
  • Functional properties of packaging films prepared with cellulose derivatives were measured. As a presolvation treatments of celluloses, 95% ethanol solution for methylcellulose (MC), hydroxypropyl-methylcellulose (HPMC) and ethylcellulose (EC) and water for hydroxypropyl cellulose (HPC) were used. For film sheeting, the ethanol concentration of final cellulose solution should exceed 50% for MC, HPMC and HPC and 80% for EC. Thickness and functionalities of the prepared films were varied by type, molecular weight and viscosity of the cellulose and kind of plasticizer used. Tensile strength of MC, HPMC and HPC films were $67.7{\sim}275.4\;MPa$, $124.6{\sim}260.0\;MPa$, and $14.8{\sim}29.4\;MPa$, respectively. The strength of MC and HPMC films was higher than that of low density polyethylene (LDPE) films $(13.1{\sim}27.6\;MPa)$. Solubility of the cellulose films varied widely by plasticizer used and the films containing polyethyleneglycol (PEG) as a plasticizer was more soluble than the films by glycerol. Maximum water vapor permeability and oxygen permeability of the cellulose films was more than 1,000 folds and less than one-twelfth of the LDPE film, respectively.

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Effect of Polycaprolactone on the Mechanical Properties of PEG/HMX Propellant (Polycaprolactone이 PEG/HMX 추진제의 기계적 성질에 미치는 영향)

  • 정병훈;홍명표;임유진
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 1998.10a
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    • pp.21-21
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    • 1998
  • Polyethylene glycol(PEG) 또는 polycaprolactone(PCP)을 예비 중합체로 사용하고 butanetriol trinitrate와 diethylene glycoldinitrate를 가소제로, cyclo-tetramethylene tetranitramine을 주산화제로 사용한 고체 추진제를 제조하여 이들의 기계적 성질을 증진시키기 위한 연구를 하였다. PEG의 일부를 PCP로 대체 시 추진제의 기계적 성질은 증가하며 PCP만 사용시 추진제의 최대 인장 강도는 PEG만 사용시 보다 약 17%, 최대 응력 하에서의 신율은 약 59% 그리고 탄성 계수는 약 9% 증가한다. 그러나 예비 중합체로 PCP만을 사용한 추진제는 4$0^{\circ}C$, 90% 상대 습도하에서 보관시 추진제의 경도 변화 실험에서 6주 후에 경도가 0이 되며, 위의 조건하에서 보관 기간에 따른 PCP 바인더의 부피 팽윤 실험에 의해 초기 부피 팽윤 비와 팽윤비의 변화 속도가 PEG를 혼용한 바인더보다 크므로 PCP 사용시 수분에 대한 안정성은 저하됨을 알 수 있었다.

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A study of injury mechanism and neural plasticity of traumatic brain injury (외상성 뇌손상의 손상 기전과 신경가소성에 대한 고찰)

  • Song Ju-min;Kim Jin-Sang
    • The Journal of Korean Physical Therapy
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    • v.16 no.2
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    • pp.90-98
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    • 2004
  • Traumatic brain injury is an insult to the brain caused by an external physical force, that may product a diminished or altered state of consciousness, which results in impairment of cognitive abilities or physical function. The purposes of this study were to overview injury mechanism and neural plasticity of traumatic brain injury. Injury mecanism includes exitotoxicity, production free radical, inflammation and apoptosis. Furthermore traumatic brain injury has protective mechanisms includes production of neural growth factor, heat shock protein, anti-inflammatory cytokines.

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Neurobiological Mechanism of Psychotherapy (정신치료의 신경생물학적 기전)

  • Lee, Seung-Hwan;Kim, Seung-Hyun
    • Korean Journal of Biological Psychiatry
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    • v.9 no.2
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    • pp.79-94
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    • 2002
  • Polarisation of biological and psychosocial aspects of psychiatry is nowadays main stream. Current knowledges of the interaction between biology and psychology make it possible to consider a truly integrative approach of the two aspects. Research findings suggest that the neuronal plasticity is the key mechanism to answer how the mental function work to an environmental stimuli and how the psychotherapeutic approach work on the brain. Advances in neuroscience research have led to a more sophisticated understanding of how psychotherapy may affect brain function. Even though there have been a tremendous efforts to find out the neurobiological mechanism of mental function, the answer is at best premature. In this article, research findings about of neuronal plasticity, implicit memory, animal studies which were associated with psychotherapy and psychological aspects were reviewed.

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The Effects of Plasticizer Addition on the Conductivity of Polymer Electrolyte Based on Poly(ethylene oxide) (이온전도성 Poly(ethylene oxide) 고분자 전해질의 전도도에 미치는 가소제 첨가 효과)

  • 문성인;진봉수;김종욱;윤문수;구할본
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1994.11a
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    • pp.82-85
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    • 1994
  • The purpose of this study is to research and develop solid polymer electrolyte(SPE) for Li secondary battery. This paper describes effects of plasticizer addition and temperature dependence of conductivity of these PEO electrolytes. Adding propylene carbonate and ethylene carbonate to PEO-LiClO$_4$electrolyte, its conductivity was higher than PEO-LiClO$_4$ itself. Steady state current method and AC impedance used for the determination of transference number in PEO electrolyte film. The transference number of PEO$\_$8/LiClO$_4$PC$\_$5/EC$\_$5/ polymer electrolyte film is 0.45 at 60$^{\circ}C$.

A Study of Drag Reduction by Polymer Additives in Rotating Disk Geometry (회전 Disk계에서 고분자 첨가제에 의한 마찰저항감소 연구)

  • 최형진
    • The Korean Journal of Rheology
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    • v.3 no.1
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    • pp.76-85
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    • 1991
  • 적은양의 분자량이 큰선형 고부자를 수용액에 첨가함으로서 얻어지는 마찰저항가소 연구가 rotating disk 장치를 이용해 수행되었다. 마찰저항 감소제로 poly(ethylene oxide)와 poly(acrylamide)를 사용하였으며 고분자 분자량 고분자 농도, disk 의 회전속도 및 온도 등 여러 가지 인자에 대한 마찰정항감소의 의존성을 연구하였다. 또한 마찰저항 감소 효과와 고분자 용액의 점도평균 분자량을 동시에 측정함으로서 고분자 퇴화에 대한 연구도 수행하 였다. 마찰저항감소는 고분자 농도가 증가함에 따라 임계농도에 도달할때까지 증가하였고 낮은 농도에서는 분자량이 큰 고분자일수록 더욱 큰 마찰저항 감소효과를 나타내었다. 마찰 감소 진행 중의 높은 전단력에 기인하는 고분자의 분해는 고분자 농도가 낮은데에서 더욱두 드러지게 나타났으며 온도 효과의 연구로부터 poly(acrylamide)가 poly(ethylene oxide)보다 열적으로 안정함을 알수 있었다.

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The Problem and it's Countermeasure of the Gasohol (가소홀의 문제점과 그 대책)

  • 류정인
    • Journal of the korean Society of Automotive Engineers
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    • v.9 no.2
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    • pp.12-16
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    • 1987
  • 세계각국에서는 원류의 소비절약과 대체연료의 개발에 발차를 기하는 등 유류파동에 휘말리지 않 으려고 노력하고 있다. 그러한 노력의 일찬으로 기존기한을 크게 개조 및 수정하지 않는 범위 에서 메타놀 등의 알콜류에 대한 연국가 활발히 진행되고 있다. 그 예로서 가솔린에 10-20%의 알콜을 혼합하면 안티노크성이 증가되고 기관의 운전이 원활하다는 것이 오래전부터 알려져 있 었다. 자동차의 배출가스문제가 제기되면서 이와 같은 종류으 혼합연료를 배기대책에 이용하는 것이 검토되었다. 더욱이 가솔린이나 경유에 알콜 등의 함산소화합물, 기타 첨가제를 혼합하여 연소를 개신하고 배출가스를 저장하는 가능성에 대한 연구가 많이 진행되었다. 지금까지의 연 구에서는 알콜, 에테르 등 항산소화합물의 일부가 적당하게 이용됨에 따라 순수가 솔린만을 사 용하는 것 보다도 배출가스의 점에서 유리하다고 알려졌다. 또 최근에는 석유자원을 절약하는 보조연료로서 또 장래의 대체연료로서 그 평가의 관점이 바뀌고 있다.

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Effect of Diethylphthalate on the Release of Salicylic Acid from Ethylcellulose Films (소수성 가소제 Diethylphthalate가 Ethylcellulose 필름으로부터의 살리씰산 방출에 미치는 영향)

  • 이승용;신상철;이민화;심창구
    • YAKHAK HOEJI
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    • v.28 no.3
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    • pp.169-177
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    • 1984
  • Release characteristics of salicylic acid from ethylcellulose(EC) films containing varying ratio of dieththylphthalate (DEP) were studied. Mathematical analysis of the release data showed that the release behavior actually conforms with the Higuchi's diffusion-controlled model. The release rate constants(k) were independent from the film thickness and the pH of release medium, but were proportional to the concentration of salicylic acid itself. The logarithm of the release rate constant (log k) increased as the concentration of DEP was increased. In conclusion, hydrophobic plastisizer DEP seemed to be very useful in controlling release rate constant of slightly soluble drugs as like salicylic acid without changing it's release characteristics.

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A Study on the Effect of Reactive Plasticizer (반응성(反應性) 가소제(可塑劑)의 효과(效果)에 관한 연구(硏究))

  • Park, Gun-Rok;Kim, Hong-Sun;Choi, Sei-Young
    • Elastomers and Composites
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    • v.27 no.4
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    • pp.247-254
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    • 1992
  • The purpose of this dissertation is to study the vulcanization characteristics, compression set and other physical properties of NBR vulcanizates according to the various plasticizer and its content. Vulcanization characteristics were investigated by using cure that has obtained by means of rheometer and Mooney viscometer. The result of physical properties, vulcanization characteristics are as fellows. 1. The results of test for optimum cure time in vulcanization characteristics of NBR compounds indicated the rapidity of scorch time according to the increase of amounts of plasticizer. 2. In the test of compression set property, LCR was the best effect. 3. In the test of oil resistance, LCR was the best effect.

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Fabrication of Water-based Ceramic Tapes Using PVP As Binder (PVP 결합제를 이용한 수계용 세라믹테이프의 제조)

  • 박일석;조유정;이명현;최세영;이득용;김대준
    • Journal of the Korean Ceramic Society
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    • v.38 no.11
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    • pp.1060-1066
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    • 2001
  • Water-based alumina tapes for application of all-ceramic crowns were fabricated using PVP as binder that is biocompatible, highly soluble in solvents, and no residue leftafter firing. Tensile strength of alumina tapes was governed by binder/(binder+plasticizer)ratio. On the other hand, linear shrinkage and density were determined by alumina/(alumina+organic) ratio. Composite for all-ceramic crowns, prepared by infiltration of a glass into sintered porous alumina, showed high flexural strength which increased with increasing sintered density.

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